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• How do you design a database to allow fast multicolumn searching?

  - by Fletcher Moore

  I am creating a real estate search from RETS data, but this is a general question. When you have a variety of columns that you would like the user to be able to filter their search result by, how do you optimize this? For example, http://www.charlestonrealestateguide.com/listings.php has 16 or so optional filters. Granted, he only has up to 11,000 entries (I have the same data), but I don't imagine the search is performed with just a giant WHERE AND AND AND ... clause. Or is this typically accomplished with one giant multicolumn index? Newegg, Amazon, and countless others also have cool & fast filtering systems for large amounts of data. How do they do it? And is there a database optimization reason for the tendency to provide ranges instead of empty inputs, or is that merely for user convenience?

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• Which encoding (code page) is used for file names in ZIP archive under Mac OS x 10.6

  - by bao

  I have a zip library SharpZipLib which intended to work with ZIP archives using C#. It has parameter ICSharpCode.SharpZipLib.Zip.ZipConstants.DefaultCodePage which specifies encoding of file names in zip archive. I know that in Windows and in OSX different encodings are used to store file names. 1) Which encodings (code pages) are used in both? 2) How to determine programmatically which encoding is used? When I open in Win7 zip file packed under MacOS X, I see files with bad names (originally - cyrillic) and folder called __MACOSX, so I can say zip was prepared on Mac box. Any other way? What about other UNIX like systems?

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• Bash variable kills script execusion

  - by Kyle Terry

  Sorry if this is better suited at serverfault, but I think it learns more towards the programming side of things. I have some code that's going into /etc/rc.local to detect what type of touch screen monitor is plugged in and changes out the xorg.conf before launching X. Here is a small snippet: CURRENT_MONITOR=`ls /dev/usb | grep 'egalax_touch\|quanta_touch'` case $CURRENT_MONITOR in '') CURRENT_MONITOR='none' ;; esac If one of those two touch screens is plugged in, it works just fine. If any other monitor is plugged in, it stops at the "CURRENT_MONITOR=ls /dev/usb | grep 'egalax_touch\|quanta_touch'." For testing I touched two files. One before creating CURRENT_MONITOR and one after CURRENT_MONITOR and only file touched before is created. I'm not a bash programmer so this might be something very obvious.

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• Build Interactive Floor With Projection !?

  - by Synxmax

  Dear Guys I am somehow newbie and sometimes guru , but at this moment i don't have enough time to research My nightmare is , my boss ask me to create an interactive floor ( he just saw in an exhibition ) , he ask me to create one of them instead of buying , i am an actionscript crawler and developer with some skills in java and c# programming , i just made some track motion with a simple web cam , and this idea came to my mind if i can use an infrared or thermographic camera instead of simple camera so i can get better positioning if camera place at top of floor ! Now i just came here to ask you guys is there any resource , tip , help i can know before getting into this deal !? is there any lib or api out to deal with this ?! EVEN, if there is any resource , article from another language c++ , c , .... could help i just didn't have enough time to test lot of ways If you search interactive floors , or interactive floor projection you can find some companies who provide such a thing Thanks in advance ( and sorry for my damn poor english , français could be better :D )

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• How can I enable/disable network connection options programmatically

  - by nikie

  When I open the properties on a network connnection on windows, I see this dialog: In this dialog, in the check-listbox I can enable or disable options like "File or printer sharing", "client for microsoft networks" or network filter drivers. My question is: How can I enable/disable these options programatically? I didn't find anything that looks like this in the WMI documentation and I couldn't find any other Win32 API for this. I would prefer a C Win32 API or WMI interface, but a solution using any programming language is welcome. The question is language-agnostic.

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• Finding the angle of a fleeing dodo.

  - by donthackmyacc

  I'm coding some critter AI for a game i am working on for my Unity 3D project. I have no programming background and have been stumbling through this using tutorials and other peoples scripts. My problem is that i want my critter to run directly away from the player when the player kicks it. I need the dodo to run directly away from the player when kicked, and i dont know the math nor the syntax to calculate that angle. They are two characters moving independently through worldspace. Here is what i got so far: waypoint = (fleeWP.transform.position); transform.LookAt(Vector3(waypoint.x, transform.position.y, waypoint.z)); transform.Translate (Vector3.forward * speed * Time.deltaTime); This currently makes the critter move towards the waypoint, rather than away. I might be attacking this all wrong. Please chastise me.

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• Cross-platform SOA framework

  - by ByteMR

  I'm looking for a good cross-platform SOA framework that preferably works with several programming languages like C++, Python, and C#. I recently learned about Thrift, but that doesn't seem to work with MSVC from the documentation I've read and requires the use of Cygwin or MinGW to even compile the Thrift compiler. Does Thrift work with MSVC and if not, are there any alternatives that would meet my needs? Such as being able to generate C# and Python bindings and work on Linux, Mac, and Windows. Any suggestions would be greatly appreciated!

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• AVD Failed to Load ~ Failed to Parse Properties ~ Mac OSX

  - by C.D. OKeefe

  I'm going to say upfront, please forgive me. I'm a newbie to android development and fairly new to programming. Also on a Mac. You're going to have to talk...real...slow. I can't get an AVD to load. I've tried it from Eclipse and from the Android SDK Manager. Failed multiple times. Received the same error each time, "Failed to parse properties from Users/myname/.android/avd/nameIGaveEmulator/config.ini." I've the forum here and saw that others have had similar problems, but of the answers given, no one came back to say if they worked, and I don't see anyone with a similar problem on a Mac. If the path needs to be "changed" what exactly does that mean and how do I go about doing so?

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• Ambiguous Evaluation of Lambda Expression on Array

  - by Joe

  I would like to use a lambda that adds one to x if x is equal to zero. I have tried the following expressions: t = map(lambda x: x+1 if x==0 else x, numpy.array) t = map(lambda x: x==0 and x+1 or x, numpy.array) t = numpy.apply_along_axis(lambda x: x+1 if x==0 else x, 0, numpy.array) Each of these expressions returns the following error: ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() My understanding of map() and numpy.apply_along_axis() was that it would take some function and apply it to each value of an array. From the error it seems that the the lambda is being evaluated as x=array, not some value in array. What am I doing wrong? I know that I could write a function to accomplish this but I want to become more familiar with the functional programming aspects of python.

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• iPhone write to file (alternative directory)

  - by strider2k

  New to iPhone 3.2, Apple introduced File-Sharing support. Details can be found at https://developer.apple.com/iphone/library/releasenotes/General/WhatsNewIniPhoneOS/Articles/iPhoneOS3_2.html#//apple_ref/doc/uid/TP40009337-SW1 . Now, most examples floating around in the web demonstrates writing to the documents directory. What if I want to write files from my app but I don't want the user to be able to see it via iTunes? I'm looking at the Files and Networking section of the iPhone OS Programming Guide and I'm unsure what would be a good alternative to the documents directory for writing files to hide from the user and not be rejected by Apple's review team.

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• bitshift large strings for encoding QR Codes

  - by icekreaman

  As an example, suppose a QR Code data stream contains 55 data words (each one byte in length) and 15 error correction words (again one byte). The data stream begins with a 12 bit header and ends with four 0 bits. So, 12 + 4 bits of header/footer and 15 bytes of error correction, leaves me 53 bytes to hold 53 alphanumeric characters. The 53 bytes of data and 15 bytes of ec are supplied in a string of length 68 (str68). The problem seems simple enough - concatenate 2 bytes of (right-shifted) header data with str68 and then left shift the entire 70 bytes by 4 bits. This is the first time in many years of programming that I have ever needed to do something like this, I am a c and bit shifting noob, so please be gentle... I have done a little investigation and so far have not been able to figure out how to bitshift 70 bytes of data; any help would be greatly appreciated. Larger QR codes can hold 2000 bytes of data...

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• How do I create a view with a picker on the bottom and a table view on the top?

  - by Andy

  Hi - first time asker, long-time lurker. I am trying to create an iPhone view that has a date/time picker on the bottom half of the screen, and a grouped, single-section, four-row table view on the top half of the screen (almost identical to the one Apple shows in Fig. 2-4 of their View Controller Programming Guide (but then never goes on to explain). Conceptually, I think I understand that what I need is a main view with a pair of subviews - one for the picker, and one for the table view. I'm pretty sure I can make the picker function once I have it on-screen, and I'm pretty sure I can make the table view function too. What I can't for the life of me figure out is how, programmatically speaking, to get the two views onto the screen simultaneously. I can lay it out perfectly in Interface Builder, but then it all goes to hell when I switch to Xcode...the view appears with the picker, but no table view. Thanks, in advance, for any help you can offer.

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• What's the best way to match a query to a set of keywords?

  - by Ryan Detzel

  Pretty much what you would assume Google does. Advertisers come in and big on keywords, lets say "ipod", "ipod nano", "ipod 60GB", "used ipod", etc. Then we have a query, "I want to buy an ipod nano" or "best place to buy used ipods" what kind of algorithms and systems are used to match those queries to the keyword set. I would imagine that some of those keyword sets are huge, 100k keywords made up of one or more actual words. on top of that queries can be 1-n words as well. Any thoughts, links to wikipedia I can start reading? From what I know already I would use some stemmed hash in disk(CDB?) and a bloom filter to check to see if I should even go to disk.

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• Crystal Reports and WMF image

  - by Eve

  I have a problem with inserting a vector graphics (WMF) into report (Crystal Reports v10.5 from Visual Studio 2008). The image is static, inserted by choosing "Insert Picture" during report design in VS. The problem is that it displays differently (size and aspect ratio) on machines with different operating systems and screen resolutions. Converting to bitmap isn't possible beacause loss of the quality of print isn't acceptable. I thought about dynamic loading of the image, but in this version of CR. I don't see a possibility to set dynamic graphic location in picture properties. Is there any way to solve this problem?

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• Sending mail via sendmail from python

  - by Nate

  If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process? Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice? I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP. As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to popen('/usr/bin/sendmail', 'w') is a little closer to the metal than I'd like. If the answer is 'go write a library,' so be it ;-)

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• C++ library for Coordinate Transformation Matrices (CTM)?

  - by BastiBense

  I'm looking for a C++ library which allows for easy integration of Coordinate Transformation Matrices (CTM) in my application. You might know CTMs from PDF or PostScript. For one project we are using C++/Qt4 as a framework, which offers a QTransform class, which provides methods like .translate(double x, double y) or .rotate(double degrees). After doing some transformations, it would allow me to get all 6 CTM values, which I could feed into a PDF library or use a transformation matrix in export files. Qt's API also allows for arbitrary mapping of polygons (QPolygon), rectangles (QRect) and other primitive data structures into transformed coordinate systems. So basically I'm looking for something similar to what Qt provides, but without the need of using Qt. I know I could do the matrix multiplications myself, but I'm not really interested in doing so, as I'm very sure that someone already solved this problem, so please no links to books or other guides on how to multiply matrices. Thanks!

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• How to implement square root and exponentiation on arbitrary length numbers?

  - by tomp

  I'm working on new data type for arbitrary length numbers (only non-negative integers) and I got stuck at implementing square root and exponentiation functions (only for natural exponents). Please help. I store the arbitrary length number as a string, so all operations are made char by char. Please don't include advices to use different (existing) library or other way to store the number than string. It's meant to be a programming exercise, not a real-world application, so optimization and performance are not so necessary. If you include code in your answer, I would prefer it to be in either pseudo-code or in C++. The important thing is the algorithm, not the implementation itself. Thanks for the help.

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• Write a function in c that includes the following sequence of statements [Wont Compile]

  - by Cody

  There is a question in my programming languages textbook that is as follows: Write a C function that includes the following sequence of statements: x = 21; int x; x = 42; Run the program and explain the results. Rewrite the same code in C++ and Java and compare the results. I have written code, and played with it in all three languages but I can not even get it to compile. This includes declaring x above the three lines as well as in the calling function (as this question is obviously attempting to illustrate scoping issues) I'd like to explain the results and do the comparisons on my own, as it is an assignment question but I was wondering if anyone had any insight as to how to get this code to compile? Thanks

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• How do you make Python wait so that you can read the output?

  - by anonnoir

  I've always been a heavy user of Notepad2, as it is fast, feature-rich, and supports syntax highlighting. Recently I've been using it for Python. My problem: when I finish editing a certain Python source code, and try to launch it, the screen disappears before I can see the output pop up. Is there any way for me to make the results wait so that I can read it, short of using an input() or time-delay function? Otherwise I'd have to use IDLE, because of the output that stops for you to read. (My apologies if this question is a silly one, but I'm very new at Python and programming in general.)

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• How to write applications that modifies the Windows UI?

  - by StevenGilligan

  Hi, I have this programming question that's been bothering me for some time now. I'm wondering how is it possible to write applications that change the Windows UI? More precisely how could you write an application that modifies the Windows Taskbar or the Windows Desktop? I'm really interested in this topic but cannot find a lot of information. I've read about extending the Windows Shell but I can't seem to find anything related to modifying the Taskbar and the Desktop. I'm looking for something along the lines of Rainmeter. How did those guys create an application that lives inside the Windows Desktop? I'd like to point out that my prefered language for this would be C# but if you want to give me hints in other languages I'm fine with it and I am running on Windows 7. Thank you

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• Empty or "flush" a file descriptor without read()?

  - by Teddy

  (Note: This is not a question of how to flush a write(). This is the other end of it, so to speak.) Is it possible to empty a file descriptor that has data to be read in it without having to read() it? You might not be interested in the data, and reading it all would therefore waste space and cycles you might have better uses for. If it is not possible in POSIX, do any operating systems have any non-portable ways to do this? UPDATE: Please note that I'm talking about file descriptors, not streams.

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• How to print an isosceles triangle

  - by Steve

  Hello, I'm trying to learn programming by myself, I'm working from a book that has the following problem which I can't solve: Allow the user to input two values: a character to be used for printing an isosceles triangle and the size of the peak for the triangle. For example, if the user inputs # for the character and 6 for the peak, you should produce the following display: # ## ### #### ##### ###### ##### #### ### ## # This is the code I've got so far: char character; int peak; InputValues(out character, out peak); for (int row = 1; row < peak * 2; row++) { for (int col = 1; col <= row; col++) { Console.Write(character); } Console.WriteLine(); } Console.Read() // hold console open Thanks in advance.

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• Differences in MS Office Charts

  - by simendsjo

  I'm about to do some Office integration creating charts from some data-sources and adding them to PPT slides. But some coworkers are saying using PPT charts is suboptimal as they are missing features of Excel charts, and are different in many ways. They're unable to come up with examples, and so am I... I found the following blog about Office2007, saying there are some differences in the programming model, but that they all use the same underlying engine. Are there really any differences in the capabilities of the charts? Is it mostly UI issues? What features are different/missing from PPT charts? Are these issues resolved in Office2010?

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• Preallocate memory for a program in Linux before it gets started

  - by Fyg

  Hi, folks, I have a program that repeatedly solves large systems of linear equations using cholesky decomposition. Characterising is that I sometimes need to store the complete factorisation which can exceed about 20 GB of memory. The factorisation happens inside a library that I call. Furthermore, this matrix and the resulting factorisation changes quite frequently and as such the memory requirements as well. I am not the only person to use this compute-node. Therefore, is there a way to start the program under Linux and preallocate free memory for the process? Something like: $: prealloc -m 25G ./program

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• Need help for this syntax: "#define LEDs (char *) 0x0003010"

  - by Noge

  I'm doing programming of a softcore processor, Nios II from Altera, below is the code in one of the tutorial, I manage to get the code working by testing it on the hardware (DE2 board), however, I could not understand the code. #define Switches (volatile char *) 0x0003000 #define LEDs (char *) 0x0003010 void main() { while (1) *LEDs = *Switches; } What I know about #define is that, it is either used to define a constant, or a macro, but why in the above code, there are casting like, (char *) 0x0003010, in #define? why the 2 constants, Switches and LEDs act like a variable instead of a constant? Thanks in advance !

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