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• MySQL LEFT JOIN, GROUP BY and ORDER BY not working as required

  - by Simon

  I have a table 'products' => ('product_id', 'name', 'description') and a table 'product_price' => ('product_price_id', 'product_id', 'price', 'date_updated') I want to perform a query something like SELECT `p`.*, `pp`.`price` FROM `products` `p` LEFT JOIN `product_price` `pp` ON `pp`.`product_id` = `p`.`product_id` GROUP BY `p`.`product_id` ORDER BY `pp`.`date_updated` DESC As you can probably guess the price changes often and I need to pull out the latest one. The trouble is I cannot work out how to order the LEFT JOINed table. I tried using some of the GROUP BY functions like MAX() but that would only pull out the column not the row. Thanks.

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• C# GroupJoin efficiency

  - by bsnote

  without using GroupJoin: var playersDictionary = players.ToDictionary(player => player.Id, element => new PlayerDto { Rounds = new List<RoundDto>() }); foreach (var round in rounds) { PlayerDto playerDto; playersDictionary.TryGetValue(round.PlayerId, out playerDto); if (playerDto != null) { playerDto.Rounds.Add(new RoundDto { }); } } var playerDtoItems = playersDictionary.Values; using GroupJoin: var playerDtoItems = from player in players join round in rounds on player.Id equals round.PlayerId into playerRounds select new PlayerDto { Rounds = playerRounds.Select(playerRound => new RoundDto {}) }; Which of these two pieces is more efficient?

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• How to split and join array in C++?

  - by Richard Knop

  I have a byte array like this: lzo_bytep out; // my byte array size_t uncompressedImageSize = 921600; out = (lzo_bytep) malloc((uncompressedImageSize + uncompressedImageSize / 16 + 64 + 3)); wrkmem = (lzo_voidp) malloc(LZO1X_1_MEM_COMPRESS); // Now the byte array has 802270 bytes r = lzo1x_1_compress(imageData, uncompressedImageSize, out, &out_len, wrkmem); How can I split it into smaller parts under 65,535 bytes (the byte array is one large packet which I want to sent over UDP which has upper limit 65,535 bytes) and then join those small chunks back into a continuous array?

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• Selecting data from mysql table and related data from another to join them

  - by knittledan

  Ive looked at other questions and answers but still dont understand which brings me here. I have one data base two tables. lets say table1 and table2 from database. I'm looking to grab all the information from table1 and only one column from table2 that coincides with the correct row in table1. Example which I know is wrong: SELECT table1.*, table2.time_stamp FROM table1, table2 WHERE table1.ticket_id=$var AND table1.user_id = table2.user_id Basically select data from table1 then use a value from the selected table to grab the related data from table2 and join them to output them as one mysql_query. Im sure its simple and has been asked before. edit: I dont receive an error. SQL just returns noting. log form of this would be: $sqlResults = mysql_query("SELECT table1.* FROM table1 WHERE table1.ticket_id=$var") while($rowResult = mysql_fetch_array( $sqlResults )) { $userID = $rowResult['user_id']; $sqlResults2 = mysql_query("SELECT table2.time_stamp FROM table2 WHERE table2.user_id=$userID") } I want to combine that into one sql statement so i dont have to hit table2 for every row table1 has

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• linq2sql left join with "multiselect"

  - by just_azho

  Hi, folks I'm trying to achieve following by linq2sql, but not successful. I've Member and Reference tables. DB is design in such a manner that Member can have multiple (=0) References. What I want as a result of query is, list (rows) of members, where all references of the member are "collected" in one column. What I had achieved is following query, but for this one there exist a row for each Reference. var refs = (from m in db.Members join r in db.References on m.PID equals r.PID into g from o in g.DefaultIfEmpty() select new { member = m, name = (o == null ? "" : o.NameSurname) }); I feel I need to insert SelectMany somewher :) Could you please give hints on achieving the goal?

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• MySQL: Matching inexact values using "ON"

  - by Brad

  I'm way out of my league here... I have a mapping table (table1) to assign particular values (value) to a whole number (map_nu). My second table (table2), is a collection of averages (avg) (I couldn't figure out how to properly make a markdown table, please feel free to edit!) table1: table2: (value)(Map_nu) (avg) ---- ----- 1 1 1.111 1.045 2 1.2 1.09 3 1.33333 1.135 4 1 1.18 5 1.389 1.225 6 1.42 1.27 7 1.07 1.315 8 1.36 9 1.405 10 I need to find a way to match the averages from table2 to the closest value in table1. It only need to match to the 2 digit past the decimal, so I've added the Truncated function SELECT map_nu FROM `table1` JOIN table2 ON TRUNCATE(table1.value,2)=TRUNCATE(table2.avg,2) I still miss the values that don't match the averages exactly. Is there a way to pick the nearest truncated value? Thanks!

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• MySQL Query to receive random combinations from two tables.

  - by Michael

  Alright, here is my issue, I have two tables, one named firstnames and the other named lastnames. What I am trying to do here is to find 100 of the possible combinations from these names for test data. The firstnames table has 5494 entries in a single column, and the lastnames table has 88799 entries in a single column. The only query that I have been able to come up with that has some results is: select * from (select * from firstnames order by rand()) f LEFT JOIN (select * from lastnames order by rand()) l on 1=1 limit 10; The problem with this code is that it selects 1 firstname and gives every lastname that could go with it. While this is plausible, I will have to set the limit to 500000000 in order to get all the combinations possible without having only 20 first names(and I'd rather not kill my server). However, I only need 100 random generations of entries for test data, and I will not be able to get that with this code. Can anyone please give me any advice?

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• Mysql - Join matches and non-matches

  - by jwzk

  This is related to my other question: http://stackoverflow.com/questions/2579249/managing-foreign-keys I am trying to join the table of matches and non-matches. So I have a list of interests, a list of users, and a list of user interests. I want the query to return all interests, whether the user has the interest or not (should be null in that case), only where the user = x. Every time I get the query working its only matching interests that the user specifically has, instead of all interests whether they have it or not.

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• Join data from two Lists into one object

  - by Petr Mensik

  I ran into following situation and I am wondering about best solution. Let's say I have List<Object1> and List<Object2>, these lists are result of two separated queries. Both of them have the same size and there is relationship 1:1 between elements in the lists based on ID. I know that best solution would be fetching data in one DB query but that's possible right now. So my question is, what is the best way to join these lists into let's say List<Object3>?

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• is NATURAL JOIN any better than SELECT FROM WHERE in terms of performance ?

  - by ashy_32bit

  Today I got into a debate with my project manager about Cartesian products. He says a 'natural join' is somehow much better than using 'select from where' because the later cause the db engine to internally perform a Cartesian product but the former uses another approach that prevents this. As far as I know, the natural join syntax is not any different in anyway than 'select from where' in terms of performance or meaning, I mean you can use either based on your taste. SELECT * FROM table1,table2 WHERE table1.id=table2.id SELECT * FROM table1 NATURAL JOIN table2 please elaborate about the first query causing a Cartesian product but the second one being somehow more smart

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• Symfony use NativeSQL to JOIN unrelated tables

  - by keybored

  I'd like to run a query like this: $rsm = new ResultSetMappingBuilder($this->em); $rsm->addRootEntityFromClassMetadata('myBundle:Foo', 'f'); $rsm->addRootEntityFromClassMetadata('myBundle:Bar', 'b'); $sql = 'SELECT l.*, b.* FROM foos f INNER JOIN FROM bars b ON b.baz_id = f.baz_id WHERE l.bam = 1'; $query = $this->em->createNativeQuery($sql, $rsm); $fooBarQuery= $query->getResult(); Unfortunately this is not a situation where I can set up a proper relationship in the entity. Is not going to be possible for me to do this? Thanks.

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• mysql count(*) left join group by - the number of files in a folder

  - by Flavius

  Hi I have the following tables CREATE TABLE `files` ( `fileid` int(11) NOT NULL AUTO_INCREMENT, `filename` varchar(255) NOT NULL, `filesize` int(11) NOT NULL, `folder` int(11) NOT NULL, PRIMARY KEY (`fileid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; CREATE TABLE `folders` ( `directoryid` int(11) NOT NULL AUTO_INCREMENT, `directoryname` varchar(255) NOT NULL, PRIMARY KEY (`directoryid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; How to get a list of all folders and the number of files they hold, including folders who have no (zero) files? Recursion must not be taken into account. Found it select folders.directoryid, folders.directoryname, count(files.fileid) as no_files from folders left join files on files.folder = folders.directoryid group by folders.directoryid, folders.directoryname I hope it will help someone.

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• reterview data from two tables using inner join in cakephp

  - by user3593884

  I two tables from database one as user(id,first_name,last_name) and the second table location(id,country). I need to perform inner join with this two tables and the list should display first_name,last_name,country with condition user.id=location.id I have written sql queries in cakephp $this->set('users',$this->User->find('list', array( 'fields' => array('User.id', 'User.first_name','location.country'), array('joins' => array(array('table' => 'location', 'alias' => 'location', 'type' => 'INNER', 'conditions' => array('User.id = location.id'))))))); i get error -Unknown column 'location.country' in 'field list' Please help!

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• Working with sets of rows in (My)SQL and comparing values

  - by Pep.

  Hello, I am trying to figure out the SQL for doing some relatively simple operations on sets of records in a table but I am stuck. Consider a table with multiple rows per item, all identified by a common key. For example: serial model color XX1 A blue XX2 A blue XX3 A green XX5 B red XX6 B blue XX1 B blue What I would for example want to do is: Assuming that all model A rows must have the same color, find the rows which dont. (for example, XX3 is green). Assuming that a given serial number can only point to a single type of model, find out the rows which that does not occur (for example XX1 points both to A and B) These are all simple logically things to do. To abstract it, I want to know how to group things by using a single key (or combination of keys) and then compare the values of those records. Should I use a join on the same table? should i use some sort of array or similar? thanks for your help

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• MySQL query to find the most popular value in a column joined by another value in a second table

  - by Budove

  I have two tables: users: user_id, user_zip settings: user_id, pref_ex_loc I need to find the single most popular 'pref_ex_loc' from the settings table based on a particular user_zip, which will be specified as the variable $userzip. Here is the query that I have now and obviously it doesn't work. $popularexloc = "SELECT pref_ex_loc, user_id COUNT(pref_ex_loc) AS countloc FROM settings FULL OUTER JOIN users ON settings.user_id = users.user_id WHERE users.user_zip='$userzip' GROUP BY settings.pref_ex_loc ORDER BY countloc LIMIT 1"; $popexloc = mysql_query($popularexloc) or die('SQL Error :: '.mysql_error()); $exlocrow = mysql_fetch_array($popexloc); $mostpopexloc=$exlocrow[0]; echo '<option value="'.$mostpopexloc.'">'.$mostpopexloc.'</option>'; What am I doing wrong here? I'm not getting any kind of error from this either.

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• retrieve data from multiple tables referencing some tables in mysql

  - by I Like PHP

  i have 10 tables have innoDB engine 1. one is state_table which attributes are state_id and state_name 2. another table city_table which attributes are city_id and city_name 3. one more table permit_table which attribute is p_id above city_id,state_id and permit_id is references to rest of 7 tables. each table having state_id, city_id and permit_id referencing above tables now i want to extract all tables data with their respective city name and state name ( each tables may have different city id and state id) i m using below mysql query( i know it's very length way.... ) . please tell me how to do it with optimized method? SELECT p.*,cp.city_name,sp.state_name, o.*,co.city_name,so.state_name, t.*,ct.city_name,st.state_name, th.*,cth.city_name,sth.state_name, f.*,cf.city_name,sf.state_name .......so on................ .......so on................ ............................ FROM permit_table p JOIN table_city cp ON cp.city_id=p.city_id JOIN table_state sp ON sp.state_id=p.state_id JOIN table_one o ON o.permit_id=p.permit_id JOIN table_city co ON co.city_id=o.city_id JOIN table_state so ON so.state_id=o.state_id JOIN table_two t ON t.permit_id=p.permit_id JOIN table_city ct ON ct.city_id=t.city_id JOIN table_state st ON st.state_id=t.state_id JOIN table_three th ON th.permit_id=p.permit_id JOIN table_city cth ON cth.city_id=th.city_id JOIN table_state sth ON sth.state_id=th.state_id JOIN table_four f ON f.permit_id=p.permit_id JOIN table_city cf ON cf.city_id=f.city_id JOIN table_state sf ON sf.state_id=f.state_id ................so on......................... ................so on......................... .............................................. WHERE p.permit_id=base64_encode(mysql_real_escape_string($_GET[pid])); Thanks For help me always.

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• retrive data from multiple tables referencing some tables in mysql

  - by I Like PHP

  i have 10 tables have innoDB engine 1. one is state_table which attributes are state_id and state_name 2. another table city_table which attributes are city_id and city_name 3. one more table permit_table which attribute is p_id above city_id,state_id and permit_id is references to rest of 7 tables. each table having state_id, city_id and permit_id referencing above tables now i want to extract all tables data with their respective city name and state name ( each tables may have different city id and state id) i m using below mysql query( i know it's very length way.... ) . please tell me how to do it with optimized method? SELECT p.*,cp.city_name,sp.state_name, o.*,co.city_name,so.state_name, t.*,ct.city_name,st.state_name, th.*,cth.city_name,sth.state_name, f.*,cf.city_name,sf.state_name .......so on................ .......so on................ ............................ FROM permit_table p JOIN table_city cp ON cp.city_id=p.city_id JOIN table_state sp ON sp.state_id=p.state_id JOIN table_one o ON o.permit_id=p.permit_id JOIN table_city co ON co.city_id=o.city_id JOIN table_state so ON so.state_id=o.state_id JOIN table_two t ON t.permit_id=p.permit_id JOIN table_city ct ON ct.city_id=t.city_id JOIN table_state st ON st.state_id=t.state_id JOIN table_three th ON th.permit_id=p.permit_id JOIN table_city cth ON cth.city_id=th.city_id JOIN table_state sth ON sth.state_id=th.state_id JOIN table_four f ON f.permit_id=p.permit_id JOIN table_city cf ON cf.city_id=f.city_id JOIN table_state sf ON sf.state_id=f.state_id ................so on......................... ................so on......................... .............................................. WHERE p.permit_id=base64_encode(mysql_real_escape_string($_GET[pid]); Thanks For help me always.

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• Hashing words to numbers with respect to definition

  - by thornate

  As part of a larger project, I need to read in text and represent each word as a number. For example, if the program reads in "Every good boy deserves fruit", then I would get a table that converts 'every' to '1742', 'good' to '977513', etc. Now, obviously I can just use a hashing algorithm to get these numbers. However, it would be more useful if words with similar meanings had numerical values close to each other, so that 'good' becomes '6827' and 'great' becomes '6835', etc. As another option, instead of a simple integer representing each number, it would be even better to have a vector made up of multiple numbers, eg (lexical_category, tense, classification, specific_word) where lexical_category is noun/verb/adjective/etc, tense is future/past/present, classification defines a wide set of general topics and specific_word is much the same as described in the previous paragraph. Does any such an algorithm exist? If not, can you give me any tips on how to get started on developing one myself? I code in C++.

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• entity set expansion python

  - by Nicolas M.

  Do you know of any existing implementation in any language (preferably python) of any entity set expansion algorithms, such that the one from Google sets ? ( http://labs.google.com/sets ) I couldn't find any library implementing such algorithms and I'd like to play with some of those to see how they would perform on some specific task I would like to implement. Any help is welcome ! Thanks a lot for your help, Regards, Nicolas.

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• Sentiment analysis for twitter in python

  - by Ran

  I'm looking for an open source implementation, preferably in python, of Textual Sentiment Analysis (http://en.wikipedia.org/wiki/Sentiment_analysis). Is anyone familiar with such open source implementation I can use? I'm writing an application that searches twitter for some search term, say "youtube", and counts "happy" tweets vs. "sad" tweets. I'm using Google's appengine, so it's in python. I'd like to be able to classify the returned search results from twitter and I'd like to do that in python. I haven't been able to find such sentiment analyzer so far, specifically not in python. Are you familiar with such open source implementation I can use? Preferably this is already in python, but if not, hopefully I can translate it to python. Note, the texts I'm analyzing are VERY short, they are tweets. So ideally, this classifier is optimized for such short texts. BTW, twitter does support the ":)" and ":(" operators in search, which aim to do just this, but unfortunately, the classification provided by them isn't that great, so I figured I might give this a try myself. Thanks! BTW, an early demo is here and the code I have so far is here and I'd love to opensource it with any interested developer.

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• Perl Lingua giving weird error on install

  - by user299306

  I am trying to install perl Lingua onto a unix system (ubuntu, latest version). Of course I am root. when I go into the package to install using 'perl Makefile.pl' I get this dumb error: [root@csisl27 Lingua-Lid-0.01]# perl Makefile.PL /opt/ls//lib does not exist at Makefile.PL line 48. I have tried playing with the path on line 48, nothing changes, here is what line 48-50 looks like: Line 48: die "$BASE/lib does not exist" unless -d "$BASE/lib"; Line 49: die "$BASE/include does not exist" unless -d "$BASE/include"; Line 50: die "lid.h is missing in $BASE/include" unless -e "$BASE/includ/lid.h"; The variable $BASE is declared as this: $BASE = "/opt/ls/" if ($^O eq "linux" or $^O eq "solaris"); $BASE = "/usr/local/" if ($^O eq "freebsd"); $BASE = $ENV{LID_BASE_DIR} if (defined $ENV{LID_BASE_DIR}); Now the perl program I am trying to write simply look like this (just my base): #!/usr/bin/perl use Lingua::LinkParser; use strict; print "Hello world!\n"; When I run this trying to use Lingua, here is my error: [root@csisl27 assign4]# ./perl_parser_1.pl Can't locate Lingua/LinkParser.pm in @INC (@INC contains: /usr/lib/perl5/site_perl/5.10.0/x86_64-linux-thread-multi /usr/lib/perl5/site_perl/5.10.0 /usr/lib/perl5/vendor_perl/5.10.0/x86_64-linux-thread-multi /usr/lib/perl5/vendor_perl/5.10.0 /usr/lib/perl5/5.10.0/x86_64-linux-thread-multi /usr/lib/perl5/5.10.0 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl .) at ./perl_parser_1.pl line 3. BEGIN failed--compilation aborted at ./perl_parser_1.pl line 3. Tried insalling this from cpan, still doesn't properly work.

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• How to honor/inherit user's language settings in WinForm app

  - by msorens

  I have worked with globalization settings in the past but not within the .NET environment, which is the topic of this question. What I am seeing is most certainly due to knowledge I have yet to learn so I would appreciate illumination on the following. Setup: My default language setting is English (en-us specifically). I added a second language (Danish) on my development system (WinXP) and then opened the language bar so I could select either at will. I selected Danish on the language bar then opened Notepad and found the language reverted to English on the language bar. I understand that the language setting is per application, so it seemed that Notepad set the default back to English. (I found that strange since Windows and thus Notepad is used all over the world.) Closing Notepad returned the setting on the language bar to Danish. I then launched my open custom WinForm application--which I know does not set the language--and it also reverted from English to Danish when opened, then back to Danish when terminated! Question #1A: How do I get my WinForm application upon launch to inherit the current setting of the language bar? My experiment seems to indicate that each application starts with the system default and requires the user to manually change it once the app is running--this would seem to be a major inconvenience for anyone that wants to work with more than one language! Question #1B: If one must, in fact, set the language manually in a multi-language scenario, how do I change my default system language (e.g. to Danish) so I can test my app's launch in another language? I added a display of the current language in my application for this next experiment. Specifically I set a MouseEnter handler on a label that set its tooltip to CultureInfo.CurrentCulture.Name so each time I mouse over I thought I should see the current language setting. Since setting the language before I launch my app did not work, I launched it then set the language to Danish. I found that some things (like typing in a TextBox) did honor this Danish setting. But mousing over the instrumented label still showed en-us! Question #2A: Why does CultureInfo.CurrentCulture.Name not reflect the change from my language bar while other parts of my app seem to recognize the change? (Trying CultureInfo.CurrentUICulture.Name produced the same result.) Question #2B: Is there an event that fires upon changes on the language bar so I could recognize within my app when the language setting changes?

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• How to implement a SIMPLE "You typed ACB, did you mean ABC?"

  - by marcgg

  I know this is not a straight up question, so if you need me to provide more information about the scope of it, let me know. There are a bunch of questions that address almost the same issue (they are linked here), but never the exact same one with the same kind of scope and objective - at least as far as I know. Context: I have a MP3 file with ID3 tags for artist name and song title. I have two tables Artists and Songs The ID3 tags might be slightly off (e.g. Mikaell Jacksonne) I'm using ASP.NET + C# and a MSSQL database I need to synchronize the MP3s with the database. Meaning: The user launches a script The script browses through all the MP3s The script says "Is 'Mikaell Jacksonne' 'Michael Jackson' YES/NO" The user pick and we start over Examples of what the system could find: In the database... SONGS = {"This is a great song title", "This is a song title"} ARTISTS = {"Michael Jackson"} Outputs... "This is a grt song title" did you mean "This is a great song title" ? "This is song title" did you mean "This is a song title" ? "This si a song title" did you mean "This is a song title" ? "This si song a title" did you mean "This is a song title" ? "Jackson, Michael" did you mean "Michael Jackson" ? "JacksonMichael" did you mean "Michael Jackson" ? "Michael Jacksno" did you mean "Michael Jackson" ? etc. I read some documentation from this /how-do-you-implement-a-did-you-mean and this is not exactly what I need since I don't want to check an entire dictionary. I also can't really use a web service since it's depending a lot on what I already have in my database. If possible I'd also like to avoid dealing with distances and other complicated things. I could use the google api (or something similar) to do this, meaning that the script will try spell checking and test it with the database, but I feel there could be a better solution since my database might end up being really specific with weird songs and artists, making spell checking useless. I could also try something like what has been explained on this post, using Soundex for c#. Using a regular spell checker won't work because I won't be using words but names and 'titles'. So my question is: is there a relatively simple way of doing this, and if so, what is it? Any kind of help would be appreciated. Thanks!

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• Stanford Parser - Traversing the typed dependencies graph

  - by pns

  Hello! Basically I want to find a path between two NP tokens in the dependencies graph. However, I can't seem to find a good way to do this in the Stanford Parser. Any help? Thank You Very Much

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• Latent Dirichlet Allocation, pitfalls, tips and programs

  - by Gregg Lind

  I'm experimenting with Latent Dirichlet Allocation for topic disambiguation and assignment, and I'm looking for advice. Which program is the "best", where best is some combination of easiest to use, best prior estimation, fast How do I incorporate my intuitions about topicality. Let's say I think I know that some items in the corpus are really in the same category, like all articles by the same author. Can I add that into the analysis? Any unexpected pitfalls or tips I should know before embarking? I'd prefer is there are R or Python front ends for whatever program, but I expect (and accept) that I'll be dealing with C.

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