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• Estimating the boundary of arbitrarily distributed data

  - by Dave

  I have two dimensional discrete spatial data. I would like to make an approximation of the spatial boundaries of this data so that I can produce a plot with another dataset on top of it. Ideally, this would be an ordered set of (x,y) points that matplotlib can plot with the plt.Polygon() patch. My initial attempt is very inelegant: I place a fine grid over the data, and where data is found in a cell, a square matplotlib patch is created of that cell. The resolution of the boundary thus depends on the sampling frequency of the grid. Here is an example, where the grey region are the cells containing data, black where no data exists. OK, problem solved - why am I still here? Well.... I'd like a more "elegant" solution, or at least one that is faster (ie. I don't want to get on with "real" work, I'd like to have some fun with this!). The best way I can think of is a ray-tracing approach - eg: from xmin to xmax, at y=ymin, check if data boundary crossed in intervals dx y=ymin+dy, do 1 do 1-2, but now sample in y An alternative is defining a centre, and sampling in r-theta space - ie radial spokes in dtheta increments. Both would produce a set of (x,y) points, but then how do I order/link neighbouring points them to create the boundary? A nearest neighbour approach is not appropriate as, for example (to borrow from Geography), an isthmus (think of Panama connecting N&S America) could then close off and isolate regions. This also might not deal very well with the holes seen in the data, which I would like to represent as a different plt.Polygon. The solution perhaps comes from solving an area maximisation problem. For a set of points defining the data limits, what is the maximum contiguous area contained within those points To form the enclosed area, what are the neighbouring points for the nth point? How will the holes be treated in this scheme - is this erring into topology now? Apologies, much of this is me thinking out loud. I'd be grateful for some hints, suggestions or solutions. I suspect this is an oft-studied problem with many solution techniques, but I'm looking for something simple to code and quick to run... I guess everyone is, really! Cheers, David

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• How To Load Images into Custom UITableViewCell?

  - by Clifton Burt

  This problem is simple, but crucial and urgent. Here's what needs to be done: load 66px x 66px images into the table cells in the MainViewController table. each TableCell has a unique image. But how? Would we use cell.image?... cell.image = [UIImage imageNamed:@"image.png"]; If so, where? Is an if/else statement required? Help? Here's the project code, hosted on Google Code, for easy and quick reference... http://www.google.com/codesearch/p?hl=en#Fcn2OtVUXnY/trunk/apple-sample-code/NavBar/NavBar/MyCustomCell.m&q=MyCustomCell%20lang:objectivec To load each cell's labels, MainViewController uses an NSDictionary and NSLocalizedString like so... //cell one menuList addObject:[NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"PageOneTitle", @""), kTitleKey, NSLocalizedString(@"PageOneExplain", @""), kExplainKey, nil]]; //cell two menuList addObject:[NSDictionary dictionaryWithObjectsAndKeys: NSLocalizedString(@"PageOneTitle", @""), kTitleKey, NSLocalizedString(@"PageOneExplain", @""), kExplainKey, nil]]; ... // this is where MainViewController loads the cell content - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { MyCustomCell *cell = (MyCustomCell*)[tableView dequeueReusableCellWithIdentifier:kCellIdentifier]; if (cell == nil) { cell = [[[MyCustomCell alloc] initWithFrame:CGRectZero reuseIdentifier:kCellIdentifier] autorelease]; } ... // MyCustomCell.m adds the subviews - (id)initWithFrame:(CGRect)aRect reuseIdentifier:(NSString *)identifier { self = [super initWithFrame:aRect reuseIdentifier:identifier]; if (self) { // you can do this here specifically or at the table level for all cells self.accessoryType = UITableViewCellAccessoryDisclosureIndicator; // Create label views to contain the various pieces of text that make up the cell. // Add these as subviews. nameLabel = [[UILabel alloc] initWithFrame:CGRectZero]; // layoutSubViews will decide the final frame nameLabel.backgroundColor = [UIColor clearColor]; nameLabel.opaque = NO; nameLabel.textColor = [UIColor blackColor]; nameLabel.highlightedTextColor = [UIColor whiteColor]; nameLabel.font = [UIFont boldSystemFontOfSize:18]; [self.contentView addSubview:nameLabel]; explainLabel = [[UILabel alloc] initWithFrame:CGRectZero]; // layoutSubViews will decide the final frame explainLabel.backgroundColor = [UIColor clearColor]; explainLabel.opaque = NO; explainLabel.textColor = [UIColor grayColor]; explainLabel.highlightedTextColor = [UIColor whiteColor]; explainLabel.font = [UIFont systemFontOfSize:14]; [self.contentView addSubview:explainLabel]; //added to mark where the thumbnail image should go imageView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 66, 66)]; [self.contentView addSubview:imageView]; } return self; } HELP?

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• How can I group an array of rectangles into "Islands" of connected regions?

  - by Eric

  The problem I have an array of java.awt.Rectangles. For those who are not familiar with this class, the important piece of information is that they provide an .intersects(Rectangle b) function. I would like to write a function that takes this array of Rectangles, and breaks it up into groups of connected rectangles. Lets say for example, that these are my rectangles (constructor takes the arguments x, y, width,height): Rectangle[] rects = new Rectangle[] { new Rectangle(0, 0, 4, 2), //A new Rectangle(1, 1, 2, 4), //B new Rectangle(0, 4, 8, 2), //C new Rectangle(6, 0, 2, 2) //D } A quick drawing shows that A intersects B and B intersects C. D intersects nothing. A tediously drawn piece of ascii art does the job too: +-------+ +---+ ¦A+---+ ¦ ¦ D ¦ +-+---+-+ +---+ ¦ B ¦ +-+---+---------+ ¦ +---+ C ¦ +---------------+ Therefore, the output of my function should be: new Rectangle[][]{ new Rectangle[] {A,B,C}, new Rectangle[] {D} } The failed code This was my attempt at solving the problem: public List<Rectangle> getIntersections(ArrayList<Rectangle> list, Rectangle r) { List<Rectangle> intersections = new ArrayList<Rectangle>(); for(Rectangle rect : list) { if(r.intersects(rect)) { list.remove(rect); intersections.add(rect); intersections.addAll(getIntersections(list, rect)); } } return intersections; } public List<List<Rectangle>> mergeIntersectingRects(Rectangle... rectArray) { List<Rectangle> allRects = new ArrayList<Rectangle>(rectArray); List<List<Rectangle>> groups = new ArrayList<ArrayList<Rectangle>>(); for(Rectangle rect : allRects) { allRects.remove(rect); ArrayList<Rectangle> group = getIntersections(allRects, rect); group.add(rect); groups.add(group); } return groups; } Unfortunately, there seems to be an infinite recursion loop going on here. My uneducated guess would be that java does not like me doing this: for(Rectangle rect : allRects) { allRects.remove(rect); //... } Can anyone shed some light on the issue?

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• How do I stack images to simulate depth using Core Animation?

  - by Jeffrey Berthiaume

  I have a series of UIImages with which I need to simulate depth. I can't use scaling because I need to be able to rotate the parent view, and the images should look like they're stacked visibly in front of each other, not on the same plane. I made a new ViewController-based project and put this in the viewDidLoad (as well as attached three 120x120 pixel images named 1.png, 2.png, and 3.png): - (void)viewDidLoad { // display image 3 UIImageView *three = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"3.png"]]; three.center = CGPointMake(160 + 60, 240 - 60); [self.view addSubview:three]; // rotate image 3 around the z axis // THIS IS INCORRECT CATransform3D theTransform = three.layer.transform; theTransform.m34 = 1.0 / -1000; three.layer.transform = theTransform; // display image 2 UIImageView *two = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"2.png"]]; two.center = CGPointMake(160, 240); [self.view addSubview:two]; // display image 1 UIImageView *one = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"1.png"]]; one.center = CGPointMake(160 - 60, 240 + 60); [self.view addSubview:one]; // rotate image 3 around the z axis // THIS IS INCORRECT theTransform = one.layer.transform; theTransform.m34 = 1.0 / 1000; one.layer.transform = theTransform; // release the images [one release]; [two release]; [three release]; // rotate the parent view around the y axis theTransform = self.view.layer.transform; theTransform.m14 = 1.0 / -500; self.view.layer.transform = theTransform; [super viewDidLoad]; } I have very specific reasons why I'm not using an EAGLView and why I'm not loading the images as CALayers (i.e. why I'm using UIImageViews for each one). This is just a quick demo that I can use to work out exactly what I need in my parent application. Is there some matrix way to translate these 2d images along the z-axis so they will look like what I'm trying to represent? I've gone through the other StackOverflow articles as well as the Wikipedia references, and have not found what I'm looking for -- although I might not necessarily be using the right terms for what I'm trying to do.

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• which way is correct to retrive data from oracle??

  - by rima

  before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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• Rails learn's confusion

  - by Steve

  This is a beginner's rails learning confusion. When I learn rails, from time to time, I feel frustrated on rails' principle "Convention over Configuration". Rails uses heavily on conventions. A lot of them are just naming conventions. If I forget a convention, I will either use the wrong naming and get unexpected result or get things magically done but don't understand how. Sometimes, I think of configuration. At least configuration lists everything clearly and nothing is in fog. In rails, there seems a hidden, dark contract between you and the machine. If you follow the contract, you communicate well. But a beginner usually forgets items listed on the contract and this usually leads to confusion. That's why when I first pick up rails, I feel like it is somehow difficult to learn. Besides, there are many other things that could be new to a learner, such as using git, using plugins from community, using RESTful routing style, using RSpec. All these are new and come together in learning ruby and rails. This definitely adds up difficulties for a beginner. In contrast, if you learn php, it wouldn't be that bad. You can forget many things and focus on learning php itself. You don't need to learn database handling if you know SQL already(in rails, you need to learn a whole new concept migration), you don't have to learn a new decent unit test(in rails, usually they teach RSpec along the way because rails is agile and you should learn test-driven development in the early learning stage), you don't have to learn a new version control(in rails, you will be taught about git anyway), you don't have to use complicated plugins(in rails, they usually use third-party plugins in textbook examples! what the hell? why not teach how to do a simplified similar thing in rails?), you don't have to worry RESTful style. All in all, when I learn php, I learn it quick and soon I start to write things myself. Learning php is similar to learning C/java. It tastes like those traditional languages. When I learn rails, it is more difficult. And I need to learn ruby as well (I believe many of you learn ruby just because of rails). Does anyone have the similar feeling as I have? How do you overcome it and start to master rails? Hints will be welcomed. Thank you.

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• Primary language - C++/Qt, C#, Java?

  - by Airjoe

  I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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• Is there a way to enforce/preserve order of XML elements in an XML Schema?

  - by MarcoS

  Let's consider the following XML Schema: <?xml version="1.0" encoding="UTF-8"?> <schema targetNamespace="http://www.example.org/library" elementFormDefault="qualified" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:lib="http://www.example.org/library"> <element name="library" type="lib:libraryType"></element> <complexType name="libraryType"> <sequence> <element name="books" type="lib:booksType"></element> </sequence> </complexType> <complexType name="booksType"> <sequence> <element name="book" type="lib:bookType" maxOccurs="unbounded" minOccurs="1"></element> </sequence> </complexType> <complexType name="bookType"> <attribute name="title" type="string"></attribute> </complexType> </schema> and a corresponding XML example: <?xml version="1.0" encoding="UTF-8"?> <lib:library xmlns:lib="http://www.example.org/library" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.example.org/library src/library.xsd "> <lib:books> <lib:book title="t1"/> <lib:book title="t2"/> <lib:book title="t3"/> </lib:books> </lib:library> Is there a way to guarantee that the order of <lib:book .../> elements is preserved? I want to be sure that any parser reading the XML will return books in the specified oder, that is first the book with title="t1", then the book with title="t2", and finally the book with title="t3". As far as I know XML parsers are not required to preserve order. I wonder whether one can enforce this through XML Schema? One quick solution for me would be adding an index attribute to the <lib:book .../> element, and delegate order preservation to the application reading the XML. Comments? Suggestions?

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• 2nd Year College - Learning - Microsoft Server Products

  - by Ryan

  As the title says, I just finished my first year of college (majoring in Software Engineering). Fortunately my school likes Microsoft enough, and I can get pretty much anything I want that Microsoft sells. I also can get IBM Websphere and the like for free as well. Earlier this year, I set up an oldish computer (2.6 Pentium D, x64) to run ubuntu server headless. I'm predominately a Java developer, so Apache, Maven, Nexus, Sonar, SVN, etc made it onto the machine. It worked really well for personal and school projects, especially team projects (quick ramp up). Anyways, I started to pick up C# to complement my Java knowledge (don't judge me :P), and am interested in working with some of the associated Microsoft equivalents. The machine currently has the Ubuntu install, as well as Windows 7 Ultimate. I do all of my actual development work off my laptop, also running Windows 7 Ultimate. I was wondering what software you would recommend putting on the machine. I’m not actually serving anything off the machine itself, but in Ubuntu I had it doing integration tests with Hudson on every commit, and profiling my applications, etc, etc. The machine would be running headless, and I would remote into it. Here is what I am currently leaning towards / wondering about: Windows 7 Ultimate vs Windows Server 2008 (R2) (no one is really clear why I should go with one over the other) Windows Team Foundation Sharepoint (Never used it before, kind of meh about it) IBM Websphere or Glassfish (Some Java EE web server) SQL Server 2008 A DVCS In order to better control product conflicts / limit resource use, I’m wondering if I should install things into virtual machines (I can get VmWare or Microsoft Virtualization Products) I also plan on installing everything I had running under Linux (it’s almost entirely Java based development software, so it’ll run on both, only reason I went with ubuntu during the year was because the apache build seemed better). I’m primarily looking to become familiar with enterprise software development tools, as well as get something functional that will help my development process. (IE, I’ll still use project and assign tasks even though I might be the only one to assign tasks to, just to practice doing so). Is there any other software / configuration details I should explore? Opinions on my current list? I primarily use C#, Java, and PHP. I'm familiar with ruby, and python as well. Thanks!

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• weird performance in C++ (VC 2010)

  - by raicuandi

  Hello, I have this loop written in C++, that compiled with MSVC2010 takes a long time to run. (300ms) for (int i=0; i<h; i++) { for (int j=0; j<w; j++) { if (buf[i*w+j] > 0) { const int sy = max(0, i - hr); const int ey = min(h, i + hr + 1); const int sx = max(0, j - hr); const int ex = min(w, j + hr + 1); float val = 0; for (int k=sy; k < ey; k++) { for (int m=sx; m < ex; m++) { val += original[k*w + m] * ds[k - i + hr][m - j + hr]; } } heat_map[i*w + j] = val; } } } It seemed a bit strange to me, so I did some tests then changed a few bits to inline assembly: (specifically, the code that sums "val") for (int i=0; i<h; i++) { for (int j=0; j<w; j++) { if (buf[i*w+j] > 0) { const int sy = max(0, i - hr); const int ey = min(h, i + hr + 1); const int sx = max(0, j - hr); const int ex = min(w, j + hr + 1); __asm { fldz } for (int k=sy; k < ey; k++) { for (int m=sx; m < ex; m++) { float val = original[k*w + m] * ds[k - i + hr][m - j + hr]; __asm { fld val fadd } } } float val1; __asm { fstp val1 } heat_map[i*w + j] = val1; } } } Now it runs in half the time, 150ms. It does exactly the same thing, but why is it twice as quick? In both cases it was run in Release mode with optimizations on. Am I doing anything wrong in my original C++ code?

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• Why does std::map operator[] create an object if the key doesn't exist?

  - by n1ck

  Hi, I'm pretty sure I already saw this question somewhere (comp.lang.c++? Google doesn't seem to find it there either) but a quick search here doesn't seem to find it so here it is: Why does the std::map operator[] create an object if the key doesn't exist? I don't know but for me this seems counter-intuitive if you compare to most other operator[] (like std::vector) where if you use it you must be sure that the index exists. I'm wondering what's the rationale for implementing this behavior in std::map. Like I said wouldn't it be more intuitive to act more like an index in a vector and crash (well undefined behavior I guess) when accessed with an invalid key? Refining my question after seeing the answers: Ok so far I got a lot of answers saying basically it's cheap so why not or things similar. I totally agree with that but why not use a dedicated function for that (I think one of the comment said that in java there is no operator[] and the function is called put)? My point is why doesn't map operator[] work like a vector? If I use operator[] on an out of range index on a vector I wouldn't like it to insert an element even if it was cheap because that probably mean an error in my code. My point is why isn't it the same thing with map. I mean, for me, using operator[] on a map would mean: i know this key already exist (for whatever reason, i just inserted it, I have redundancy somewhere, whatever). I think it would be more intuitive that way. That said what are the advantage of doing the current behavior with operator[] (and only for that, I agree that a function with the current behavior should be there, just not operator[])? Maybe it give clearer code that way? I don't know. Another answer was that it already existed that way so why not keep it but then, probably when they (the ones before stl) choose to implement it that way they found it provided an advantage or something? So my question is basically: why choose to implement it that way, meaning a somewhat lack of consistency with other operator[]. What benefit do it give? Thanks

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• C++ DLL creation for C# project - No functions exported

  - by Yeti

  I am working on a project that requires some image processing. The front end of the program is C# (cause the guys thought it is a lot simpler to make the UI in it). However, as the image processing part needs a lot of CPU juice I am making this part in C++. The idea is to link it to the C# project and just call a function from a DLL to make the image processing part and allow to the C# environment to process the data afterwards. Now the only problem is that it seems I am not able to make the DLL. Simply put the compiler refuses to put any function into the DLL that I compile. Because the project requires some development time testing I have created two projects into a C++ solution. One is for the Dll and another console application. The console project holds all the files and I just include the corresponding header into my DLL project file. I thought the compiler should take out the functions that I marked as to be exported and make the DLL from them. Nevertheless this does not happens. Here it is how I defined the function in the header: extern "C" __declspec(dllexport) void _stdcall RobotData(BYTE* buf, int** pToNewBackgroundImage, int* pToBackgroundImage, bool InitFlag, ObjectInformation* robot1, ObjectInformation* robot2, ObjectInformation* robot3, ObjectInformation* robot4, ObjectInformation* puck); extern "C" __declspec(dllexport) CvPoint _stdcall RefPointFinder(IplImage* imgInput, CvRect &imgROI, CvScalar &refHSVColorLow, CvScalar &refHSVColorHi ); Followed by the implementation in the cpp file: extern "C" __declspec(dllexport) CvPoint _stdcall RefPointFinder(IplImage* imgInput, CvRect &imgROI,&refHSVColorLow, CvScalar &refHSVColorHi ) { \\... return cvPoint((int)( M10/M00) + imgROI.x, (int)( M01/M00 ) + imgROI.y) ;} extern "C" __declspec(dllexport) void _stdcall RobotData(BYTE* buf, int** pToNewBackgroundImage, int* pToBackgroundImage, bool InitFlag, ObjectInformation* robot1, ObjectInformation* robot2, ObjectInformation* robot3, ObjectInformation* robot4, ObjectInformation* puck) { \\ ...}; And my main file for the DLL project looks like: #ifdef _MANAGED #pragma managed(push, off) #endif /// <summary> Include files. </summary> #include "..\ImageProcessingDebug\ImageProcessingTest.h" #include "..\ImageProcessingDebug\ImageProcessing.h" BOOL APIENTRY DllMain( HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) { return TRUE; } #ifdef _MANAGED #pragma managed(pop) #endif Needless to say it does not work. A quick look with DLL export viewer 1.36 reveals that no function is inside the library. I don't get it. What I am doing wrong ? As side not I am using the C++ objects (and here it is the C++ DLL part) such as the vector. However, only for internal usage. These will not appear in the headers of either function as you can observe from the previous code snippets. Any ideas? Thx, Bernat

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• Postgresql count+sort performance

  - by invictus

  I have built a small inventory system using postgresql and psycopg2. Everything works great, except, when I want to create aggregated summaries/reports of the content, I get really bad performance due to count()'ing and sorting. The DB schema is as follows: CREATE TABLE hosts ( id SERIAL PRIMARY KEY, name VARCHAR(255) ); CREATE TABLE items ( id SERIAL PRIMARY KEY, description TEXT ); CREATE TABLE host_item ( id SERIAL PRIMARY KEY, host INTEGER REFERENCES hosts(id) ON DELETE CASCADE ON UPDATE CASCADE, item INTEGER REFERENCES items(id) ON DELETE CASCADE ON UPDATE CASCADE ); There are some other fields as well, but those are not relevant. I want to extract 2 different reports: - List of all hosts with the number of items per, ordered from highest to lowest count - List of all items with the number of hosts per, ordered from highest to lowest count I have used 2 queries for the purpose: Items with host count: SELECT i.id, i.description, COUNT(hi.id) AS count FROM items AS i LEFT JOIN host_item AS hi ON (i.id=hi.item) GROUP BY i.id ORDER BY count DESC LIMIT 10; Hosts with item count: SELECT h.id, h.name, COUNT(hi.id) AS count FROM hosts AS h LEFT JOIN host_item AS hi ON (h.id=hi.host) GROUP BY h.id ORDER BY count DESC LIMIT 10; Problem is: the queries runs for 5-6 seconds before returning any data. As this is a web based application, 6 seconds are just not acceptable. The database is heavily populated with approximately 50k hosts, 1000 items and 400 000 host/items relations, and will likely increase significantly when (or perhaps if) the application will be used. After playing around, I found that by removing the "ORDER BY count DESC" part, both queries would execute instantly without any delay whatsoever (less than 20ms to finish the queries). Is there any way I can optimize these queries so that I can get the result sorted without the delay? I was trying different indexes, but seeing as the count is computed it is possible to utilize an index for this. I have read that count()'ing in postgresql is slow, but its the sorting that are causing me problems... My current workaround is to run the queries above as an hourly job, putting the result into a new table with an index on the count column for quick lookup. I use Postgresql 9.2.

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• help me to choose the best soulotion for my purpose to build my software.

  - by rima

  before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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• Which is the "best" data access framework/approach for C# and .NET?

  - by Frans

  (EDIT: I made it a community wiki as it is more suited to a collaborative format.) There are a plethora of ways to access SQL Server and other databases from .NET. All have their pros and cons and it will never be a simple question of which is "best" - the answer will always be "it depends". However, I am looking for a comparison at a high level of the different approaches and frameworks in the context of different levels of systems. For example, I would imagine that for a quick-and-dirty Web 2.0 application the answer would be very different from an in-house Enterprise-level CRUD application. I am aware that there are numerous questions on Stack Overflow dealing with subsets of this question, but I think it would be useful to try to build a summary comparison. I will endeavour to update the question with corrections and clarifications as we go. So far, this is my understanding at a high level - but I am sure it is wrong... I am primarily focusing on the Microsoft approaches to keep this focused. ADO.NET Entity Framework Database agnostic Good because it allows swapping backends in and out Bad because it can hit performance and database vendors are not too happy about it Seems to be MS's preferred route for the future Complicated to learn (though, see 267357) It is accessed through LINQ to Entities so provides ORM, thus allowing abstraction in your code LINQ to SQL Uncertain future (see Is LINQ to SQL truly dead?) Easy to learn (?) Only works with MS SQL Server See also Pros and cons of LINQ "Standard" ADO.NET No ORM No abstraction so you are back to "roll your own" and play with dynamically generated SQL Direct access, allows potentially better performance This ties in to the age-old debate of whether to focus on objects or relational data, to which the answer of course is "it depends on where the bulk of the work is" and since that is an unanswerable question hopefully we don't have to go in to that too much. IMHO, if your application is primarily manipulating large amounts of data, it does not make sense to abstract it too much into objects in the front-end code, you are better off using stored procedures and dynamic SQL to do as much of the work as possible on the back-end. Whereas, if you primarily have user interaction which causes database interaction at the level of tens or hundreds of rows then ORM makes complete sense. So, I guess my argument for good old-fashioned ADO.NET would be in the case where you manipulate and modify large datasets, in which case you will benefit from the direct access to the backend. Another case, of course, is where you have to access a legacy database that is already guarded by stored procedures. ASP.NET Data Source Controls Are these something altogether different or just a layer over standard ADO.NET? - Would you really use these if you had a DAL or if you implemented LINQ or Entities? NHibernate Seems to be a very powerful and powerful ORM? Open source Some other relevant links; NHibernate or LINQ to SQL Entity Framework vs LINQ to SQL

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• MySQL Split Time Ranges into Smaller Chunks

  - by Neren

  Hello all, I've recently been tasked with finishing a PHP/MySQL web app when the developer quit last week. I'm no MySQL expert, so I apologize if this is an intensely simple question. I've searched SO for the better part of two days trying to find a relatively easy solution to my problem, which is as follows. Problem in a Nutshell: I have a MySQL table full of start and end datetime (GMT -5) & UNIX Timestamp values covering durations of irregular length and need to break/split/divide them into more-regular time chunks (5 minutes). I'm not after a count of row entries per time chunk/bucket/period, if that makes any sense. Data Example: started, ended, started_UNIX, ended_UNIX 2010-10-25 15:12:33, 2010-10-25 15:47:09, 1288033953, 1288036029 What I'm hoping to get: 2010-10-25 15:12:33, 2010-10-25 15:15:00, 1288033953, 1288037700 2010-10-25 15:15:00, 2010-10-25 15:20:00, 1288037700, 1288038000 2010-10-25 15:20:00, 2010-10-25 15:25:00, 1288038000, 1288038300 2010-10-25 15:25:00, 2010-10-25 15:30:00, 1288038300, 1288038600 2010-10-25 15:30:00, 2010-10-25 15:35:00, 1288038600, 1288038900 2010-10-25 15:35:00, 2010-10-25 15:40:00, 1288038900, 1288039200 2010-10-25 15:40:00, 2010-10-25 15:45:00, 1288039200, 1288039500 2010-10-25 15:45:00, 2010-10-25 15:47:09, 1288039500, 1288039629 If you're interested, here's the quick & dirty on the app and why I need the data: App overview: The application receives very simple POST requests generated by a basic sensor device when its input pins go to ground, which submits an INSERT query to the database where MySQL records a timestamp (as started). When the input pins return from a grounded state, the device submits a different POST request, which causes the PHP app to submit an UPDATE query, where a modification time timestamp is inserted (as ended). My employer recently changed the periodic reporting unit of measure from Seconds "On" Per Day to Seconds "On" Per 5 Minute Interval. I had formulated what I thought would be a workable solution, but when I looked at it on paper, it looked like Rube Goldberg's nightmare constructed in MySQL, so that was out. Any suggestions as to how to break these spans into 5 minute blocks? Keeping it all in MySQL would be my preference, though I'll take any suggestions. Thank you for any suggestions you may have. Again, I apologize if this is a no-brainer. If I ask any additional questions of the SO collective consciousness in the future, I'll try to word them a bit better. Any help will be happily welcomed. Thanks, Neren

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• Primary language - QtC++, C#, Java?

  - by Airjoe

  I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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• Why does the Ternary\Conditional operator seem significantly faster

  - by Jodrell

  Following on from this question, which I have partially answered. I compile this console app in x64 Release Mode, with optimizations on, and run it from the command line without a debugger attached. using System; using System.Diagnostics; class Program { static void Main() { var stopwatch = new Stopwatch(); var ternary = Looper(10, Ternary); var normal = Looper(10, Normal); if (ternary != normal) { throw new Exception(); } stopwatch.Start(); ternary = Looper(10000000, Ternary); stopWatch.Stop(); Console.WriteLine( "Ternary took {0}ms", stopwatch.ElapsedMilliseconds); stopwatch.Start(); normal = Looper(10000000, Normal); stopWatch.Stop(); Console.WriteLine( "Normal took {0}ms", stopwatch.ElapsedMilliseconds); if (ternary != normal) { throw new Exception(); } Console.ReadKey(); } static int Looper(int iterations, Func<bool, int, int> operation) { var result = 0; for (int i = 0; i < iterations; i++) { var condition = result % 11 == 4; var value = ((i * 11) / 3) % 5; result = operation(condition, value); } return result; } static int Ternary(bool condition, in value) { return value + (condition ? 2 : 1); } static int Normal(int iterations) { if (condition) { return = 2 + value; } return = 1 + value; } } I don't get any exceptions and the output to the console is somthing close to, Ternary took 107ms Normal took 230ms When I break down the CIL for the two logical functions I get this, ... Ternary ... { : ldarg.1 // push second arg : ldarg.0 // push first arg : brtrue.s T // if first arg is true jump to T : ldc.i4.1 // push int32(1) : br.s F // jump to F T: ldc.i4.2 // push int32(2) F: add // add either 1 or 2 to second arg : ret // return result } ... Normal ... { : ldarg.0 // push first arg : brfalse.s F // if first arg is false jump to F : ldc.i4.2 // push int32(2) : ldarg.1 // push second arg : add // add second arg to 2 : ret // return result F: ldc.i4.1 // push int32(1) : ldarg.1 // push second arg : add // add second arg to 1 : ret // return result } Whilst the Ternary CIL is a little shorter, it seems to me that the execution path through the CIL for either function takes 3 loads and 1 or 2 jumps and a return. Why does the Ternary function appear to be twice as fast. I underdtand that, in practice, they are both very quick and indeed, quich enough but, I would like to understand the discrepancy.

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• Custom cell in list in Flash AS3

  - by Stian Flatby

  I am no expert in Flash, and I need some quick help here, without needing to learn everything from scratch. Short story, I have to make a list where each cell contains an image, two labels, and a button. List/Cell example: img - label - label - button img - label - label - button As a Java-programmer, I have tried to quicly learn the syntax and visualness of Flash and AS3, but with no luck so far. I have fairly understood the basics of movie clips etc. I saw a tutorial on how to add a list, and add some text to it. So I dragged in a list, and in the code went list.addItem({label:"hello"}); , and that worked ofc. So i thought if I double-clicked the MC of the list, i would get to tweak some things. In there I have been wandering around different halls of cell-renderers etc. I have now come to the point that I entered the CellRenderer_skinUp or something, and customized it to my liking. When this was done, I expected i could use list.addItem(); and get an empty "version" of my cell, with the img, labels and the button. But AS3 expects an input in addItem. From my object-oriented view, I am thinking that i have to create an object of the cell i have made, but i have no luck reaching it.. I tried to go var test:CellRenderer = list.listItem; list.addItem(test); ..But with no luck. This is just for funsies, but I really want to make this work, however not so much that I am willing to read up on ALOT of Flash and AS3. I felt that I was closing in on the prize, but the compiler expected a semicolon after the variable (list.addItem({test:something});). Note: If possible, I do NOT want this: list.addItem({image:"src",label:"text",label"text",button:"text"}); Well.. It actually is what I want, but I would really like to custom-draw everything. Does anyone get what I am trying to do, and has any answers for me? Am I approaching this the wrong way? I have searched the interwebs for custom list-cells, but with no luck. Please, any guiding here is appreciated! Sti

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• C# Windows Service Multiple Config Files

  - by Goober

  Quick Question Is it possible to have more than 1 config file in a windows service? Or is there some way I can merge them at run time? Scenario Currently I have two config files containing the below contents. After I build and install my Windows Service, I can't get my custom XML Parser class to read the content because it keeps pointing to the wrong config file, even though I am using a few lines of code to ensure it gets the right name of the config file I need to access. ALSO When I navigate to the folder in which the service is installed, there is only sign of the normal APP.Config file, and no sign of the custom config file. (I have even set the normal ones properties to "Do Not Copy" and the custom ones properties to "Copy Always"). Config File Determination Code string settingsFile = String.Format("{0}.exe.config", System.AppDomain.CurrentDomain.BaseDirectory + Assembly.GetExecutingAssembly().GetName().Name); CUSTOM CONFIG File <?xml version="1.0" encoding="utf-8" ?> <configuration> <servers> <SV066930> <add name="Name" value = "SV066930" /> <processes> <SimonTest1> <add name="ProcessName" value="notepad.exe" /> <add name="CommandLine" value="C:\\WINDOWS\\system32\\notepad.exe C:\\WINDOWS\\Profiles\\TA2TOF1\\Desktop\\SimonTest1.txt" /> </SimonTest1> </processes> </SV066930> </servers> </configuration> NORMAL APP.CONFIG File <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=xxxxxxxxxxx" /> </configSections> <connectionStrings> <add name="DB" connectionString="Data Source=etc......" /> </connectionStrings> </configuration>

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• Are there any modern GUI toolkits which implement a heirarchical menu buffer zone?

  - by scomar

  In Bruce Tognazzini's quiz on Fitt's Law, the question discussing the bottleneck in the hierarchical menu (as used in almost every modern desktop UI), talks about his design for the original Mac: The bottleneck is the passage between the first-level menu and the second-level menu. Users first slide the mouse pointer down to the category menu item. Then, they must carefully slide the mouse directly across (horizontally) in order to move the pointer into the secondary menu. The engineer who originally designed hierarchicals apparently had his forearm mounted on a track so that he could move it perfectly in a horizontal direction without any vertical component. Most of us, however, have our forarms mounted on a pivot we like to call our elbow. That means that moving our hand describes an arc, rather than a straight line. Demanding that pivoted people move a mouse pointer along in a straight line horizontally is just wrong. We are naturally going to slip downward even as we try to slide sideways. When we are not allowed to slip downward, the menu we're after is going to slam shut just before we get there. The Windows folks tried to overcome the pivot problem with a hack: If they see the user move down into range of the next item on the primary menu, they don't instantly close the second-level menu. Instead, they leave it open for around a half second, so, if users are really quick, they can be inaccurate but still get into the second-level menu before it slams shut. Unfortunately, people's reactions to heightened chance of error is to slow down, rather than speed up, a well-established phenomenon. Therefore, few users will ever figure out that moving faster could solve their problem. Microsoft's solution is exactly wrong. When I specified the Mac hierarchical menu algorthm in the mid-'80s, I called for a buffer zone shaped like a <, so that users could make an increasingly-greater error as they neared the hierarchical without fear of jumping to an unwanted menu. As long as the user's pointer was moving a few pixels over for every one down, on average, the menu stayed open, no matter how slow they moved. (Cancelling was still really easy; just deliberately move up or down.) This just blew me away! Such a simple idea which would result in a huge improvement in usability. I'm sure I'm not the only one who regularly has the next level of a menu slam shut because I don't move the mouse pointer in a perfectly horizontal line. So my question is: Are there any modern UI toolkits which implement this brilliant idea of a < shaped buffer zone in hierarchical menus? And if not, why not?!

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• Swing: does DefaultBoundedRangeModel coalesce multiple events?

  - by Jason S

  I have a JProgressBar displaying a BoundedRangeModel which is extremely fine grained and I was concerned that updating it too often would slow down my computer. So I wrote a quick test program (see below) which has a 10Hz timer but each timer tick makes 10,000 calls to microtick() which in turn increments the BoundedRangeModel. Yet it seems to play nicely with a JProgressBar; my CPU is not working hard to run the program. How does JProgressBar or DefaultBoundedRangeModel do this? They seem to be smart about how much work it does to update the JProgressBar, so that as a user I don't have to worry about updating the BoundedRangeModel's value. package com.example.test.gui; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.BoundedRangeModel; import javax.swing.DefaultBoundedRangeModel; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JProgressBar; import javax.swing.Timer; public class BoundedRangeModelTest1 extends JFrame { final private BoundedRangeModel brm = new DefaultBoundedRangeModel(); final private Timer timer = new Timer(100, new ActionListener() { @Override public void actionPerformed(ActionEvent arg0) { tick(); } }); public BoundedRangeModelTest1(String title) { super(title); JPanel p = new JPanel(); p.add(new JProgressBar(this.brm)); getContentPane().add(p); this.brm.setMaximum(1000000); this.brm.setMinimum(0); this.brm.setValue(0); } protected void tick() { for (int i = 0; i < 10000; ++i) { microtick(); } } private void microtick() { this.brm.setValue(this.brm.getValue()+1); } public void start() { this.timer.start(); } static public void main(String[] args) { BoundedRangeModelTest1 f = new BoundedRangeModelTest1("BoundedRangeModelTest1"); f.pack(); f.setVisible(true); f.setDefaultCloseOperation(EXIT_ON_CLOSE); f.start(); } }

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• Database Schema Versioning Strategies

  - by Jack Ryan

  I work on a project that uses a reasonably large database, the live version weighing in at somewhere around 60-80GB. The live database is the only real definitive source of our schema, and because of its size duplicating this database is too slow to be done often. This means we have ended up developing our database schema in a pretty ad hoc way, using sql compare to migrate changes from dev dbs to the live system, and only wiping our dev dbs every month or two. I am hoping to get some pointers on how to improve our database development work flow so that we have a little more control. Some things to think about: Currently nobody is really in charge of the database schema, all developers can change it if they need to, though generally these decisions are talked about before they are done. There are stored procedures, functions, and views in the database. These should probably be dumped to files so they can be reloaded on every build. Schema changes should probably be checked in as scripts. We have started to do this recently. However all our scripts must then be numbered (because there may be dependencies between them), and must be re runnable (because our build script currently runs them all in order). This makes them hard to read because they are full of conditionals that check whether tables or columns already exist. This is a step that is often forgotten by developers. Getting a new database should be quick and easy. This is currently a big problem, it takes several hours to get a copy of last nights backup and restore it onto a dev machine. Some mechanism needs to be in place to allow developers to update static data. We have tables that contain data that is never updated through the application, but does potentially need to be changed when we do a new release (often this drives dropdowns). The whole thing needs to be runnable as part of a build script. Are there any tools that can be used to help to do this? Eventually I would like to be at a point where a new DB can be built from scratch without copying any data from the live system. I don't mind writing some scripts to glue all the steps together but each part should be easily editable so that we continue to use it rather than make changes directly on DBs.

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• SQL Design Question regarding schema and if Name value pair is the best solution

  - by Aur

  I am having a small problem trying to decide on database schema for a current project. I am by no means a DBA. The application parses through a file based on user input and enters that data in the database. The number of fields that can be parsed is between 1 and 42 at the current moment. The current design of the database is entirely flat with there being 42 columns; some have repeated columns such as address1, address2, address3, etc... This says that I should normalize the data. However, data integrity is not needed at this moment and the way the data is shaped I'm looking at several joins. Not a bad thing but the data is still in a 1 to 1 relationship and I still see a lot of empty fields per row. So my concerns are that this does not allow the database or the application to be very extendable. If they want to add more fields to be parsed (which they do) than I'd need to create another table and add another foreign key to the linking table. The third option is I have a table where the fields are defined and a table for each record. So what I was thinking is to make a table that stores the value and then links to those two tables. The problem is I can picture the size of that table growing large depending on the input size. If someone gives me a file with 300,000 records than 300,000 x 40 = 12 million so I have some reservations. However I think if I get to that point than I should be happy it is being used. This option also allows for more custom displaying of information albeit a bit more work but little rework even if you add more fields. So the problem boils down to: 1. Current design is a flat file which makes extending it hard and it is not normalized. 2. Normalize the tables although no real benefits for the moment but requirements change. 3. Normalize it down into the name value pair and hope size doesn't hurt. There are a large number of inserts, updates, and selects against that table. So performance is a worry but I believe the saying is design now, performance testing later? I'm probably just missing something practical so any comments would be appreciated even if it’s a quick sanity check. Thank you for your time.

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• How can I represent a line of music notes in a way that allows fast insertion at any index?

  - by chairbender

  For "fun", and to learn functional programming, I'm developing a program in Clojure that does algorithmic composition using ideas from this theory of music called "Westergaardian Theory". It generates lines of music (where a line is just a single staff consisting of a sequence of notes, each with pitches and durations). It basically works like this: Start with a line consisting of three notes (the specifics of how these are chosen are not important). Randomly perform one of several "operations" on this line. The operation picks randomly from all pairs of adjacent notes that meet a certain criteria (for each pair, the criteria only depends on the pair and is independent of the other notes in the line). It inserts 1 or several notes (depending on the operation) between the chosen pair. Each operation has its own unique criteria. Continue randomly performing these operations on the line until the line is the desired length. The issue I've run into is that my implementation of this is quite slow, and I suspect it could be made faster. I'm new to Clojure and functional programming in general (though I'm experienced with OO), so I'm hoping someone with more experience can point out if I'm not thinking in a functional paradigm or missing out on some FP technique. My current implementation is that each line is a vector containing maps. Each map has a :note and a :dur. :note's value is a keyword representing a musical note like :A4 or :C#3. :dur's value is a fraction, representing the duration of the note (1 is a whole note, 1/4 is a quarter note, etc...). So, for example, a line representing the C major scale starting on C3 would look like this: [ {:note :C3 :dur 1} {:note :D3 :dur 1} {:note :E3 :dur 1} {:note :F3 :dur 1} {:note :G3 :dur 1} {:note :A4 :dur 1} {:note :B4 :dur 1} ] This is a problematic representation because there's not really a quick way to insert into an arbitrary index of a vector. But insertion is the most frequently performed operation on these lines. My current terrible function for inserting notes into a line basically splits the vector using subvec at the point of insertion, uses conj to join the first part + notes + last part, then uses flatten and vec to make them all be in a one-dimensional vector. For example if I want to insert C3 and D3 into the the C major scale at index 3 (where the F3 is), it would do this (I'll use the note name in place of the :note and :dur maps): (conj [C3 D3 E3] [C3 D3] [F3 G3 A4 B4]), which creates [C3 D3 E3 [C3 D3] [F3 G3 A4 B4]] (vec (flatten previous-vector)) which gives [C3 D3 E3 C3 D3 F3 G3 A4 B4] The run time of that is O(n), AFAIK. I'm looking for a way to make this insertion faster. I've searched for information on Clojure data structures that have fast insertion but haven't found anything that would work. I found "finger trees" but they only allow fast insertion at the start or end of the list. Edit: I split this into two questions. The other part is here.

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