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  • What is the the relation between programming and mathematics?

    - by Math Grad
    Programmers seem to think that their work is quite mathematical. I understand this when you try to optimize something in performance, find the most efficient alogithm, etc.. But it patently seems false when you look at a billing application for a shop, or a systems software riddled with I/O calls. So what is it exactly? Is computation and associated programming really mathematical? Here I have in mind particularly the words of the philosopher Schopenhauer in mind: That arithmetic is the basest of all mental activities is proved by the fact that it is the only one that can be accomplished by means of a machine. Take, for instance, the reckoning machines that are so commonly used in England at the present time, and solely for the sake of convenience. But all analysis finitorum et infinitorum is fundamentally based on calculation. Therefore we may gauge the “profound sense of the mathematician,” of whom Lichtenberg has made fun, in that he says: “These so-called professors of mathematics have taken advantage of the ingenuousness of other people, have attained the credit of possessing profound sense, which strongly resembles the theologians’ profound sense of their own holiness.” I lifted the above quote from here. It seems that programmers are doing precisely the sort of mechanized base mental activity the grand old man is contemptuous about. So what exactly is the deal? Is programming really the "good" kind of mathematics, or just the baser type, or altogether something else just meant for business not to be confused with a pure discipline?

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  • MySQL table data transformation -- how can I dis-aggreate MySQL time data?

    - by lighthouse65
    We are coding for a MySQL data warehousing application that stores descriptive data (User ID, Work ID, Machine ID, Start and End Time columns in the first table below) associated with time and production quantity data (Output and Time columns in the first table below) upon which aggregate (SUM, COUNT, AVG) functions are applied. We now wish to dis-aggregate time data for another type of analysis. Our current data table design: +---------+---------+------------+---------------------+---------------------+--------+------+ | User ID | Work ID | Machine ID | Event Start Time | Event End Time | Output | Time | +---------+---------+------------+---------------------+---------------------+--------+------+ | 080025 | ABC123 | M01 | 2008-01-24 16:19:15 | 2008-01-24 16:34:45 | 2120 | 930 | +---------+---------+------------+---------------------+---------------------+--------+------+ Reprocessing dis-aggregation that we would like to do would be to transform table content based on a granularity of minutes, rather than the current production event ("Event Start Time" and "Event End Time") granularity. The resulting reprocessing of existing table rows would look like: +---------+---------+------------+---------------------+--------+ | User ID | Work ID | Machine ID | Production Minute | Output | +---------+---------+------------+---------------------+--------+ | 080025 | ABC123 | M01 | 2010-01-24 16:19 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:20 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:21 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:22 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:23 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:24 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:25 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:26 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:27 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:28 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:29 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:30 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:31 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:22 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:33 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:34 | 133 | +---------+---------+------------+---------------------+--------+ So the reprocessing would take an existing row of data created at the granularity of production event and modify the granularity to minutes, eliminating redundant (Event End Time, Time) columns while doing so. It assumes a constant rate of production and divides output by the difference in minutes plus one to populate the new table's Output column. I know this can be done in code...but can it be done entirely in a MySQL insert statement (or otherwise entirely in MySQL)? I am thinking of a INSERT ... INTO construction but keep getting stuck. An additional complexity is that there are hundreds of machines to include in the operation so there will be multiple rows (one for each machine) for each minute of the day. Any ideas would be much appreciated. Thanks.

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  • How to reuse results with a schema for end of day stock-data

    - by Vishalrix
    I am creating a database schema to be used for technical analysis like top-volume gainers, top-price gainers etc.I have checked answers to questions here, like the design question. Having taken the hint from boe100 's answer there I have a schema modeled pretty much on it, thusly: Symbol - char 6 //primary Date - date //primary Open - decimal 18, 4 High - decimal 18, 4 Low - decimal 18, 4 Close - decimal 18, 4 Volume - int Right now this table containing End Of Day( EOD) data will be about 3 million rows for 3 years. Later when I get/need more data it could be 20 million rows. The front end will be asking requests like "give me the top price gainers on date X over Y days". That request is one of the simpler ones, and as such is not too costly, time wise, I assume. But a request like " give me top volume gainers for the last 10 days, with the previous 100 days acting as baseline", could prove 10-100 times costlier. The result of such a request would be a float which signifies how many times the volume as grown etc. One option I have is adding a column for each such result. And if the user asks for volume gain in 10 days over 20 days, that would require another table. The total such tables could easily cross 100, specially if I start using other results as tables, like MACD-10, MACD-100. each of which will require its own column. Is this a feasible solution? Another option being that I keep the result in cached html files and present them to the user. I dont have much experience in web-development, so to me it looks messy; but I could be wrong ( ofc!) . Is that a option too? Let me add that I am/will be using mod_perl to present the response to the user. With much of the work on mysql database being done using perl. I would like to have a response time of 1-2 seconds.

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  • mysql subselect alternative

    - by Arnold
    Hi, Lets say I am analyzing how high school sports records affect school attendance. So I have a table in which each row corresponds to a high school basketball game. Each game has an away team id and a home team id (FK to another "team table") and a home score and an away score and a date. I am writing a query that matches attendance with this seasons basketball games. My sample output will be (#_students_missed_class, day_of_game, home_team, away_team, home_team_wins_this_season, away_team_wins_this_season) I now want to add how each team did the previous season to my analysis. Well, I have their previous season stored in the game table but i should be able to accomplish that with a subselect. So in my main select statement I add the subselect: SELECT COUNT(*) FROM game_table WHERE game_table.date BETWEEN 'start of previous season' AND 'end of previous season' AND ( (game_table.home_team = team_table.id AND game_table.home_score > game_table.away_score) OR (game_table.away_team = team_table.id AND game_table.away_score > game_table.home_score)) In this case team-table.id refers to the id of the home_team so I now have all their wins calculated from the previous year. This method of calculation is neither time nor resource intensive. The Explain SQL shows that I have ALL in the Type field and I am not using a Key and the query times out. I'm not sure how I can accomplish a more efficient query with a subselect. It seems proposterously inefficient to have to write 4 of these queries (for home wins, home losses, away wins, away losses). I am sure this could be more lucid. I'll absolutely add color tomorrow if anyone has questions

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  • Asymptotic runtime of list-to-tree function

    - by Deestan
    I have a merge function which takes time O(log n) to combine two trees into one, and a listToTree function which converts an initial list of elements to singleton trees and repeatedly calls merge on each successive pair of trees until only one tree remains. Function signatures and relevant implementations are as follows: merge :: Tree a -> Tree a -> Tree a --// O(log n) where n is size of input trees singleton :: a -> Tree a --// O(1) empty :: Tree a --// O(1) listToTree :: [a] -> Tree a --// Supposedly O(n) listToTree = listToTreeR . (map singleton) listToTreeR :: [Tree a] -> Tree a listToTreeR [] = empty listToTreeR (x:[]) = x listToTreeR xs = listToTreeR (mergePairs xs) mergePairs :: [Tree a] -> [Tree a] mergePairs [] = [] mergePairs (x:[]) = [x] mergePairs (x:y:xs) = merge x y : mergePairs xs This is a slightly simplified version of exercise 3.3 in Purely Functional Data Structures by Chris Okasaki. According to the exercise, I shall now show that listToTree takes O(n) time. Which I can't. :-( There are trivially ceil(log n) recursive calls to listToTreeR, meaning ceil(log n) calls to mergePairs. The running time of mergePairs is dependent on the length of the list, and the sizes of the trees. The length of the list is 2^h-1, and the sizes of the trees are log(n/(2^h)), where h=log n is the first recursive step, and h=1 is the last recursive step. Each call to mergePairs thus takes time (2^h-1) * log(n/(2^h)) I'm having trouble taking this analysis any further. Can anyone give me a hint in the right direction?

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  • Interesting questions related to lighttpd on Amazon EC2

    - by terence410
    This problem appeared today and I have no idea what is going on. Please share you ideas. I have 1 EC2 DB server (MYSQL + NFS File Sharing + Memcached). And I have 3 EC2 Web servers (lighttpd) where it will mounted the NFS folders on the DB server. Everything going smoothly for months but suddenly there is an interesting phenomenon. In every 8 minutes to 10 minutes, PHP file will be unreachable. This will last about 1 minute and then back to normal. Normal files like .html file are unaffected. All servers have the same problem exactly at the same time. I have spent one whole day to analysis the reason. Finally, I find out when the problem appear, the file descriptor of lighttpd suddenly increased a lot. I used ls /proc/1234/fd | wc -l to check the number of fd. The # of fd is around 250 in normal time. However, when the problem appeared, it will be raised to 1500 and then back to normal. It sounds funny, right? Do you have any idea what's going on? ======================== The CPU graph of one of the web server.

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  • Hadoop/MapReduce: Reading and writing classes generated from DDL

    - by Dave
    Hi, Can someone walk me though the basic work-flow of reading and writing data with classes generated from DDL? I have defined some struct-like records using DDL. For example: class Customer { ustring FirstName; ustring LastName; ustring CardNo; long LastPurchase; } I've compiled this to get a Customer class and included it into my project. I can easily see how to use this as input and output for mappers and reducers (the generated class implements Writable), but not how to read and write it to file. The JavaDoc for the org.apache.hadoop.record package talks about serializing these records in Binary, CSV or XML format. How do I actually do that? Say my reducer produces IntWritable keys and Customer values. What OutputFormat do I use to write the result in CSV format? What InputFormat would I use to read the resulting files in later, if I wanted to perform analysis over them?

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  • Access Violation in std::pair

    - by sameer karjatkar
    I have an application which is trying to populate a pair. Out of nowhere the application crashes. The Windbg analysis on the crash dump suggests: PRIMARY_PROBLEM_CLASS: INVALID_POINTER_READ DEFAULT_BUCKET_ID: INVALID_POINTER_READ STACK_TEXT: 0389f1dc EPFilter32!std::vector<std::pair<unsigned int,unsigned int>,std::allocator<std::pair<unsigned int,unsigned int> > >::size+0xc INVALID_POINTER_READ_c0000005_Test.DLL!std::vector_std::pair_unsigned_int, unsigned_int_,std::allocator_std::pair_unsigned_int,unsigned_int_____::size Following is the code snap in the code where it fails: for (unsigned i1 = 0; i1 < size1; ++i1) { for (unsigned i2 = 0; i2 < size2; ++i2) { const branch_info& b1 = en1.m_branches[i1]; //Exception here :crash const branch_info& b2 = en2.m_branches[i2]; } } where branch_info is std::pair<unsigned int,unsigned int> and the en1.m_branches[i1] fetches me a pair value.

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  • Which version of Grady Booch's OOA/D book should I buy?

    - by jackj
    Grady Booch's "Object-Oriented Analysis and Design with Applications" is available brand new in both the 2nd edition (1993) and the 3rd edition (2007), while many used copies of both editions are available. Here are my concerns: 1) The 2nd edition uses C++: given that I just finished reading my first two C++ books (Accelerated C++ and C++ Primer) I guess practical tips can only help, so the 2nd edition is probably best (I think the 3rd edition has absolutely no code). On the other hand, the C++ books I read insist on the importance of using standard C++, whereas Booch's 2nd edition was published before the 1998 standard. 2) The 2nd edition is shorter (608 pages vs. 720) so, I guess, it will be slightly easier to get through. 3) The 3rd edition uses UML 2.0, whereas the 2nd edition is pre-UML. Some reviews say that the notation in the 2nd edition is close enough to UML, so it doesn't matter, but I don't know if I should be worrying about this or not. 4) The 2nd edition is available in good-shape used copies for considerably less than what the 3rd one goes for. Given all the above factors, do you think I should buy the 2nd or the 3rd edition? Recommendations on other books are also welcome but I would prefer it if whoever answers has read at least one of the versions of Booch's book (preferably both!). I have already bought but not read GoF and Riel's books. I also know that I should practice a lot with real-life code. Thanks.

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  • Handling missing/incomplete data in R--is there function to mask but not remove NAs?

    - by doug
    As you would expect from a DSL aimed at data analysis, R handles missing/incomplete data very well, for instance: Many R functions have an 'na.rm' flag that you can set to 'T' to remove the NAs: mean( c(5,6,12,87,9,NA,43,67), na.rm=T) But if you want to deal with NAs before the function call, you need to do something like this: to remove each 'NA' from a vector: vx = vx[!is.na(a)] to remove each 'NA' from a vector and replace it w/ a '0': ifelse(is.na(vx), 0, vx) to remove entire each row that contains 'NA' from a data frame: dfx = dfx[complete.cases(dfx),] All of these functions permanently remove 'NA' or rows with an 'NA' in them. Sometimes this isn't quite what you want though--making an 'NA'-excised copy of the data frame might be necessary for the next step in the workflow but in subsequent steps you often want those rows back (e.g., to calculate a column-wise statistic for a column that has missing rows caused by a prior call to 'complete cases' yet that column has no 'NA' values in it). to be as clear as possible about what i'm looking for: python/numpy has a class, 'masked array', with a 'mask' method, which lets you conceal--but not remove--NAs during a function call. Is there an analogous function in R?

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  • Strange Matlab error: "??? Subscript indices must either be real positive integers or logicals"

    - by Roee Adler
    I have a function func that returns a vector a. I usually plot a and then perform further analysis on it. I have a certain scenario when once I try to plot a, I get a "??? Subscript indices must either be real positive integers or logicals" error. Take a look at the following piece of code to see the vector's behavior: K>> a a = 5.7047 6.3529 6.4826 5.5750 4.1488 5.8343 5.3157 5.4454 K>> plot(a) ??? Subscript indices must either be real positive integers or logicals. K>> for i=1:length(a); b(i) = a(i); end; K>> b b = 5.7047 6.3529 6.4826 5.5750 4.1488 5.8343 5.3157 5.4454 K>> plot(b) ??? Subscript indices must either be real positive integers or logicals. The scenario where this happens is when I call function func from within another function (call it outer_func), and return the result directly as outer_func's result. When debugging inside outer_func, I can plot a properly, but outside the scope of outer_func, its result has the above behavior. What can cause this? Where do I start from?

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  • Generating easy-to-remember random identifiers

    - by Carl Seleborg
    Hi all, As all developers do, we constantly deal with some kind of identifiers as part of our daily work. Most of the time, it's about bugs or support tickets. Our software, upon detecting a bug, creates a package that has a name formatted from a timestamp and a version number, which is a cheap way of creating reasonably unique identifiers to avoid mixing packages up. Example: "Bug Report 20101214 174856 6.4b2". My brain just isn't that good at remembering numbers. What I would love to have is a simple way of generating alpha-numeric identifiers that are easy to remember. Examples would be "azil3", "ulmops", "fel2way", etc. I just made these up, but they are much easier to recognize when you see many of them at once. I know of algorithms that perform trigram analysis on text (say you feed them a whole book in German) and that can generate strings that look and feel like German words. This requires lots of data, though, and makes it slightly less suitable for embedding in an application just for this purpose. Do you know of anything else? Thanks! Carl

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  • Advanced All In One .NET Framework

    - by alfredo dobrekk
    Hi, i m starting a new project that would basically take input from user and save them to database among about 30 screens, and i would like to find a framework that will allow the maximum number of these features out of the box : .net c#. windows form. unit testing continuous integration screens with lists, combo boxes, text boxes, add, delete, save, cancel that are easy to update when you add a property to your classes or a field to your database. auto completion on controls to help user find its way use of an orm like nhibernate easy multithreading and display of wait screens for user easy undo redo tabbed child windows search forms ability to grant access to some functionnalities according to user profiles mvp/mvvm or whatever design patterns either some code generation from database to c# classe or generation of database schema from c# classes some kind of database versioning / upgrade to easily update database when i release patches to application once in production automatic control resizing code metrics analysis some code generator i can use against my entities that would generate some rough form i can rearrange after code documentation generator ... Any ideas ? I know its lot but i really would like to use existing code to build upon so i can focus on business rules. Could splitting the requirements on 3 or 4 existing open source framework be possible ? Do u have any suggestion to add to the list before starting ? What open source tools would u use to achieve these ?

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  • Generic dataset handling library

    - by Pep.
    Hello, I want to build a generic Perl module for handling and analysing biomedical character separated datasets and which can, most certain, be used on any kind of datasets that contain a mixture of categorical (A,B,C,..) and continuous (1.2,3,881..) and identifier (XXX1,XXX2...). The plan is to have people initialize the module and then use some arguments to point to the data file(s), the place were the analysis reports should be placed and the structure of the data. By structure of data I mean which variable is in which place and its name/type. And this is where I need some enlightenment. I am baffled how to do this in a clean way. Obviously, having people create a simple schema file, be it XML or some other format would be the cleanest but maybe not all people enjoy doing something like this. The solutions I can think of are: Create a configuration file in XML or similar and with a prespecified format. Pass the information during initialization of the module. Use the first row of the data as headers and try to guess types (ouch) Surely there must be a "canonical" way of doing this that is also usable and efficient. Thanks p.

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  • html body inside if condition

    - by gautam
    Hi, i have two different bodies for different conditions. can i do like this.... <% if(yes) %> <body onload="JavaScript:timedRefresh(120000);"> <% } else { %> <body> <% } %> Please help me... Thanks in advance.. I want to compare my title in if condition how can i do??? currently i am doing like this: <head> <title> <tiles:getAsString name="title"/> </title> </head> <% if(%><tiles:getAsString name="title"/><%.equals("Trade Confirmation Analysis Screen")) %> <body onload="JavaScript:timedRefresh(120000);"> <%else { %> <body> <% } %> Its giving me error..Unable to compile class for JSP:

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  • writing into csv file

    - by arin
    I recived alarms in a form of text as the following NE=JKHGDUWJ3 Alarm=Data Center STALZ AC Failure Occurrence=2012/4/3 22:18:19 GMT+02:00 Clearance=Details=Cabinet No.=0, Subrack No.=40, Slot No.=0, Port No.=5, Board Type=EDS, Site No.=49, Site Type=HSJYG500 GSM, Site Name=Google1 . I need to fill it in csv file so later I can perform some analysis I came up with this namespace AlarmSaver { public partial class Form1 : Form { string filesName = "c:\\alarms.csv"; public Form1() { InitializeComponent(); } private void buttonSave_Click(object sender, EventArgs e) { if (!File.Exists(filesName)) { string header = "NE,Alarm,Occurrence,Clearance,Details"; File.AppendAllText(filesName,header+Environment.NewLine); } StringBuilder sb = new StringBuilder(); string line = textBoxAlarm.Text; int index = line.IndexOf(" "); while (index > 0) { string token = line.Substring(0, index).Trim(); line = line.Remove(0, index + 2); string[] values = token.Split('='); if (values.Length ==2) { sb.Append(values[1] + ","); } else { if (values.Length % 2 == 0) { string v = token.Remove(0, values[0].Length + 1).Replace(',', ';'); sb.Append(v + ","); } else { sb.Append("********" + ","); string v = token.Remove(0, values[0].Length + 1 + values[1].Length + 1).Replace(',', ';'); sb.Append(v + ","); } } index = line.IndexOf(" "); } File.AppendAllText(filesName, sb.ToString() + Environment.NewLine); } } } the results are as I want except when I reach the part of Details=Cabinet No.=0, Subrack No.=40, Slot No.=0, Port No.=5, Board Type=KDL, Site No.=49, Site Type=JDKJH99 GSM, Site Name=Google1 . I couldnt split them into seperate fields. as the results showing is as I want to split the details I want each element in details to be in a column to be somthin like its realy annoying :-) please help , thank you in advance

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  • Deterministic and non uniform long string generation from seed

    - by Limonup
    I had this weird idea for an encryption that I wanted to try out, it may be bad, and it may have done before, but I'm just doing it for fun. The short version of the question is: Is it possible to generate a long, deterministic and non-uniformly distributed string/sequence of numbers from a small seed? Long(er) version: I was thinking to encrypt a text by changing encoding. The new encoding would be generated via Huffman algorithm. To work well, the Huffman algorithm would need a fairly long text with non uniform distribution. Then characters can have different bit-lengths which would be the primary strength of this encryption. The problem is that its impractical to enter in/remember a long text each time you want to decrypt the text. So I was wondering if it was possible to generate a text from password seed? It doesn't matter what the text is, as long as it has non uniform distribution of characters and that the exact same sequence can be recreated each time you give it the same seed. Preferably, are there any functions/extensions in Python that can do this? EDIT: To expand on the "strength" of varying bit length: if I have a string "test", ASCII values 116, 101, 115, 116, which gives bit values of 1110100 1100101 1110011 1110100 Then, say my Huffman algorithm generates encoding like t = 101 e = 1100111 s = 10001 The final string is 101 1100111 10001 101, if we encode this back to ASCII, we get 1011100 1111000 1101000, which is 3 entirely different characters. Obviously its impossible to perform any kind of frequency analysis or something like that on this.

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  • Which to use, XMP or RDF?

    - by zotty
    What's the difference between RDF and XMP? From what I can tell, XMP is derived from RDF... so what does it offer that RDF doesn't? My particular situation is this: I've got some images which need tagging with details of how an experiment was performed, and what sort of data analysis has been performed on the images. A colleague of mine is pushing for XMP, but he's thinking of the images as photos - they're not really, they're just bits of data. From what I've seen (mainly by opening images in notepad++) the XMP data looks very similar to RDF - even so far as using RDF in the tag names (e.g. <rdf:Seq>). I'd like this data to be usable by other people who use similar instruments for similar experiments, so creating a mini standard (schema?) seems like the way to go. Apologies for the lack of fundemental understanding - I'm a Doctor, not a programmer! If it makes any difference, the language of choice will be C#. Edit for more information: First off, thanks for the excellent replies - thinking of XMP as a vocabulary for RDF makes things a lot clearer. The sort of data I'll be storing wont be avaliable in any of the pre-defined sets. It'll detail experimental set ups, locations and results. I think using RDF is the way to go.

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  • Raw types and subtyping

    - by Dmitrii
    We have generic class SomeClass<T>{ } We can write the line: SomeClass s= new SomeClass<String>(); It's ok, because raw type is supertype for generic type. But SomeClass<String> s= new SomeClass(); is correct to. Why is it correct? I thought that type erasure was before type checking, but it's wrong. From Hacker's Guide to Javac When the Java compiler is invoked with default compile policy it performs the following passes: parse: Reads a set of *.java source files and maps the resulting token sequence into AST-Nodes. enter: Enters symbols for the definitions into the symbol table. process annotations: If Requested, processes annotations found in the specified compilation units. attribute: Attributes the Syntax trees. This step includes name resolution, type checking and constant folding. flow: Performs data ow analysis on the trees from the previous step. This includes checks for assignments and reachability. desugar: Rewrites the AST and translates away some syntactic sugar. generate: Generates Source Files or Class Files. Generic is syntax sugar, hence type erasure invoked at 6 pass, after type checking, which invoked at 4 pass. I'm confused.

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  • Are functional programming languages good for practical tasks?

    - by Clueless
    It seems to me from my experimenting with Haskell, Erlang and Scheme that functional programming languages are a fantastic way to answer scientific questions. For example, taking a small set of data and performing some extensive analysis on it to return a significant answer. It's great for working through some tough Project Euler questions or trying out the Google Code Jam in an original way. At the same time it seems that by their very nature, they are more suited to finding analytical solutions than actually performing practical tasks. I noticed this most strongly in Haskell, where everything is evaluated lazily and your whole program boils down to one giant analytical solution for some given data that you either hard-code into the program or tack on messily through Haskell's limited IO capabilities. Basically, the tasks I would call 'practical' such as Aceept a request, find and process requested data, and return it formatted as needed seem to translate much more directly into procedural languages. The most luck I have had finding a functional language that works like this is Factor, which I would liken to a reverse-polish-notation version of Python. So I am just curious whether I have missed something in these languages or I am just way off the ball in how I ask this question. Does anyone have examples of functional languages that are great at performing practical tasks or practical tasks that are best performed by functional languages?

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  • How do I get started designing and implementing a script interface for my .NET application?

    - by Peter Mortensen
    How do I get started designing and implementing a script interface for my .NET application? There is VSTA (the .NET equivalent of VBA for COM), but as far as I understand I would have to pay a license fee for every installation of my application. It is an open source application so this will not work. There is also e.g. the embedding of interpreters (IronPython?), but I don't understand how this would allow exposing an "object model" (see below) to external (or internal) scripts. What is the scripting interface story in .NET? Is it somehow trivial in .NET to do this? Background: I have once designed and implemented a fairly involved script interface for a Macintosh application for acquisition and analysis of data from a mass spectrometer (Mac OS, System 7) and later a COM interface for a Windows application. Both were designed with an "object model" and classes (that can have properties). These are overloaded words, but in a scripting interface context object model is essentially a containment hiarchy of objects of specific classes. Classes have properties and lists of contained objects. E.g. like in the COM interfaces exposed in Microsoft Office applications, where the application object can be used to add to its list of documents (with the side effect of creating the GUI representation of a document). External scripts can create new objects in a container and navigate through the content of the hiarchy at any given time. In the Macintosh case scripts could be written in e.g. AppleScript or Frontier. On the Macintosh the implementation of a scripting interface was very complicated. Support for it in Metroworks' C++ class library (the name escapes me right now) made it much simpler.

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  • How to classify NN/NNP/NNS obtained from POS tagged document as a product feature

    - by Shweta .......
    I'm planning to perform sentiment analysis on reviews of product features (collected from Amazon dataset). I have extracted review text from the dataset and performed POS tagging on that. I'm able to extract NN/NNP as well. But my doubt is how do I come to know that extracted words classify as features of the products? I know there are classifiers in nltk but I don't know how I should use it for my project. I'm assuming there are 2 ways of finding whether the extracted word is a product feature or not. One is to compare with a bag of words and find out if my word exists in that. Doubt: How do I create/get bag of words? Second way is to implement some kind of apriori algorithm to find out frequently occurring words as features. I would like to know which method is good and how to go about implementing it. Some pointers to available softwares or code snippets would be helpful! Thanks!

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  • Building a control-flow graph from an AST with a visitor pattern using Java

    - by omegatai
    Hi guys, I'm trying to figure out how to implement my LEParserCfgVisitor class as to build a control-flow graph from an Abstract-Syntax-Tree already generated with JavaCC. I know there are tools that already exist, but I'm trying to do it in preparation for my Compilers final. I know I need to have a data structure that keeps the graph in memory, and I want to be able to keep attributes like IN, OUT, GEN, KILL in each node as to be able to do a control-flow analysis later on. My main problem is that I haven't figured out how to connect the different blocks together, as to have the right edge between each blocks depending on their nature: branch, loops, etc. In other words, I haven't found an explicit algorithm that could help me build my visitor. Here is my empty Visitor. You can see it works on basic langage expressions, like if, while and basic operations (+,-,x,^,...) public class LEParserCfgVisitor implements LEParserVisitor { public Object visit(SimpleNode node, Object data) { return data; } public Object visit(ASTProgram node, Object data) { data = node.childrenAccept(this, data); return data; } public Object visit(ASTBlock node, Object data) { } public Object visit(ASTStmt node, Object data) { } public Object visit(ASTAssignStmt node, Object data) { } public Object visit(ASTIOStmt node, Object data) { } public Object visit(ASTIfStmt node, Object data) { } public Object visit(ASTWhileStmt node, Object data) { } public Object visit(ASTExpr node, Object data) { } public Object visit(ASTAddExpr node, Object data) { } public Object visit(ASTFactExpr node, Object data) { } public Object visit(ASTMultExpr node, Object data) { } public Object visit(ASTPowerExpr node, Object data) { } public Object visit(ASTUnaryExpr node, Object data) { } public Object visit(ASTBasicExpr node, Object data) { } public Object visit(ASTFctExpr node, Object data) { } public Object visit(ASTRealValue node, Object data) { } public Object visit(ASTIntValue node, Object data) { } public Object visit(ASTIdentifier node, Object data) { } } Can anyone give me a hand? Thanks!

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  • C# Late Binding for Parameterized Property

    - by optim
    I'm trying to use late binding to connect to a COM automation API provided by a program called Amibroker, using a C# WinForms project. So far I've been able to connect to everything in the API except one item, which I believe to be a "parameterized property" based on extensive Googling. Here's what the API specification looks like according to the docs (Full version here: http://www.amibroker.com/guide/objects.html): Property Filter(ByVal nType As Integer, ByVal pszCategory As String) As Long [r/w] A javascript snippet to update the value looks like this: AB = new ActiveXObject("Broker.Application"); AA = AB.Analysis; AA.Filter( 0, "market" ) = 0; Using the following C# late-binding code, I can get the value of the property, but I can't for the life of me figure out how to set the value: object[] parameter = new object[2]; parameter[0] = Number; parameter[1] = Type; object filters = _analysis.GetType().InvokeMember("Filter", BindingFlags.GetProperty, null, _analysis, parameter); So far I have tried: using BindingFlags.SetProperty, BindingFlags.SetField casting the returned object to a PropertyInfo object and trying to update the value using it adding extra object containing the value to the parameters object various other things as last-ditch efforts From what I can see, this should be straight-forward, but I'm finding the late binding in C# to be cumbersome at best. The property looks like a method call to me, which is what is throwing me off. How does one assign a value to a method, and what would the prototype for late-binding C# code look like for it? Hopefully that explains it well enough, but feel free to ask if I've left anything unclear. Thanks in advance for any help! Daniel

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  • The mathematics of Schellings segregation model

    - by Bruce
    For those who don't know the model. You can read this pdf. I want to find what is the probability that 2 nodes are each others neighbors when the algorithm converges (i.e. when all nodes are happy). Here's the model in a gist. You have a grid (say 10x10). You have nodes of two kind (red and green) 45 each. So we have 10 empty spaces. We randomly place the nodes on the grid. Now we scan through this grid (Exact order does not matter according to Schelling). Each node wants a specific percentage of people of same kind in its Moore neighborhood (say b = 50% for each red and green). We calculate the happiness of each node (a = Number of neighbors of same kind/Number of neighbors of different kind). If a node is unhappy (a < b) it moves to an empty cell where it knows it will be happy. This movement can change the dynamics of old as well as new neighborhood. Algorithm converges when all nodes are happy. PS - I am looking for links for any mathematical analysis of the Schelling's model.

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