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  • Calculating Growth-Rates by applying log-differences

    - by mropa
    I am trying to transform my data.frame by calculating the log-differences of each column and controlling for the rows id. So basically I like to calculate the growth rates for each id's variable. So here is a random df with an id column, a time period colum p and three variable columns: df <- data.frame (id = c("a","a","a","c","c","d","d","d","d","d"), p = c(1,2,3,1,2,1,2,3,4,5), var1 = rnorm(10, 5), var2 = rnorm(10, 5), var3 = rnorm(10, 5) ) df id p var1 var2 var3 1 a 1 5.375797 4.110324 5.773473 2 a 2 4.574700 6.541862 6.116153 3 a 3 3.029428 4.931924 5.631847 4 c 1 5.375855 4.181034 5.756510 5 c 2 5.067131 6.053009 6.746442 6 d 1 3.846438 4.515268 6.920389 7 d 2 4.910792 5.525340 4.625942 8 d 3 6.410238 5.138040 7.404533 9 d 4 4.637469 3.522542 3.661668 10 d 5 5.519138 4.599829 5.566892 Now I have written a function which does exactly what I want BUT I had to take a detour which is possibly unnecessary and can be removed. However, somehow I am not able to locate the shortcut. Here is the function and the output for the posted data frame: fct.logDiff <- function (df) { df.log <- dlply (df, "code", function(x) data.frame (p = x$p, log(x[, -c(1,2)]))) list.nalog <- llply (df.log, function(x) data.frame (p = x$p, rbind(NA, sapply(x[,-1], diff)))) ldply (list.nalog, data.frame) } fct.logDiff(df) id p var1 var2 var3 1 a 1 NA NA NA 2 a 2 -0.16136569 0.46472004 0.05765945 3 a 3 -0.41216720 -0.28249264 -0.08249587 4 c 1 NA NA NA 5 c 2 -0.05914281 0.36999681 0.15868378 6 d 1 NA NA NA 7 d 2 0.24428771 0.20188025 -0.40279188 8 d 3 0.26646102 -0.07267311 0.47041227 9 d 4 -0.32372771 -0.37748866 -0.70417351 10 d 5 0.17405309 0.26683625 0.41891802 The trouble is due to the added NA-rows. I don't want to collapse the frame and reduce it, which would be automatically done by the diff() function. So I had 10 rows in my original frame and am keeping the same amount of rows after the transformation. In order to keep the same length I had to add some NAs. I have taken a detour by transforming the data.frame into a list, add the NAs, and afterwards transform the list back into a data.frame. That looks tedious. Any ideas to avoid the data.frame-list-data.frame class transformation and optimize the function?

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  • How to compare DateTime Objects while looping through a list?

    - by Taniq
    I'm trying to loop through a list (csv) containing two fields; a name and a date. There are various duplicated names and various dates in the list. I'm trying to deduce for each name in the list, where there are multiple instances of the same name, which corresponding date is the latest. I realise, from looking at another answer, that I need to use the DateTime.Compare method which is fine, but my problem is working out which date is later. Once I know this I need to produce a file with unique names and the latest date relating to it. This is my first question which makes me a newbie. EDIT: Initially I thought it would be 'ok' to set the LatestDate object to a date that wouldn't show up in my file, therefore making any later dates in the file the LatestDate. Here's my coding so far: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; namespace flybe_overwriter { class Program { static DateTime currentDate; static DateTime latestDate = new DateTime(1000,1,1); static HashSet<string> uniqueNames = new HashSet<string>(); static string indexpath = @"e:\flybe test\indexing.csv"; static string[] indexlist = File.ReadAllLines(indexpath); static StreamWriter outputfile = new StreamWriter(@"e:\flybe test\match.csv"); static void Main(string[] args) { foreach (string entry in indexlist) { uniqueNames.Add(entry.Split(',')[0]); } HashSet<string>.Enumerator fenum = new HashSet<string>.Enumerator(); fenum = uniqueNames.GetEnumerator(); while (fenum.MoveNext()) { string currentName = fenum.Current; foreach (string line in indexlist) { currentDate = new DateTime(Convert.ToInt32(line.Split(',')[1].Substring(4, 4)), Convert.ToInt32(line.Split(',')[1].Substring(2, 2)), Convert.ToInt32(line.Split(',')[1].Substring(0, 2))); if (currentName == line.Split(',')[0]) { if(DateTime.Compare(latestDate.Date, currentDate.Date) < 1) { // Console.WriteLine(currentName + " " + latestDate.ToShortDateString() + " is earlier than " + currentDate.ToShortDateString()); } else if (DateTime.Compare(latestDate.Date, currentDate.Date) > 1) { // Console.WriteLine(currentName + " " + latestDate.ToShortDateString() + " is later than " + currentDate.ToShortDateString()); } else if (DateTime.Compare(latestDate.Date, currentDate.Date) == 0) { // Console.WriteLine(currentName + " " + latestDate.ToShortDateString() + " is the same as " + currentDate.ToShortDateString()); } } } } } } } Any help appreciated. Thanks.

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  • Why does the web page I fetch with Perl look odd?

    - by Tichomir Mitkov
    I have a Perl script to open this page http://svejo.net/popular/all/new/ and filter the names of the posts but except headers everything seems encrypted. Nothing can be read. When I open the same page in a browser everything looks fine including the source code. How is it possible to encrypt a page for a script and not for a browser? My Perl script sends the same headers as my browser (Google Chrome).

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  • How to parse a date from an SSIS Excel filename

    - by user327045
    I want to use the foreach container to iterate through a folder matching something like: "Filename_MMYYYY.xls". That's easy enough to do; but I can't seem to find a way to parse the MMYYYY from the filename and add it to a variable (or something) that i can use as a lookup field for my DimDate table. It seems possible with a flat file data source, but not an excel connection. I'm using Visual Studio 2005. Please help!

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  • home directory and .emacs file in Windows 7

    - by prosseek
    I installed emacs 23.3.1 in c:/emacs-23.3. Following the hints in this page, I updated the site-start.el to set HOME environment variable. (setenv "HOME" "c:/users/USER/emacs") And I made c:/users/USER/.emacs (like I did in unix/mac) to write the code for using slime, but it doesn't seem to start slime correctly. Is this a correct way of setting emacs in Windows 7? Where do I put the .emacs file?

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  • How to post data in PHP using file_get_contents?

    - by Paras Chopra
    I am using PHP's function file_get_contents() to fetch contents of a URL and then I process headers through the variable $http_response_header. Now the problem is that some of the URLs need some data to be posted to the URL (for example, login pages). How do I do that? I realize using stream_context I may be able to do that but I am not entirely clear. Thanks.

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  • File size in Python server

    - by Anna
    We have server on Python and client + web service on Ruby. That works only if file from URL is less than 800 k. It seems like "socket.puts data" in a client works, but "output = socket.gets" - not. I think problem is in a Python part. For big files tests run "Connection reset by peer". Is it buffer size variable by default somewhere in a Python?

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  • Python command line - add PYTHONPATH during module run

    - by orokusaki
    I want to run: python somescript.py somecommand But, when I run this I need PYTHONPATH to include a certain directory. I can't just add it to my environment variables because the directory I want to add changes based on what project I'm running. Is there a way to alter PYTHONPATH while running a script? Note: I don't even have a PYTHONPATH variable, so I don't need to worry about appending to it vs overriding it during running of this script.

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  • pagination - 10 pages per page

    - by arthur
    I have a pagination script that displays a list of all pages like so: prev [1][2][3][4][5][6][7][8][9][10][11][12][13][14] next But I would like to only show ten of the numbers at a time: prev [3][4][5][6][7][8][9][10][11][12] next How can I accomplish this? Here is my code so far: <?php /* Set current, prev and next page */ $page = (!isset($_GET['page']))? 1 : $_GET['page']; $prev = ($page - 1); $next = ($page + 1); /* Max results per page */ $max_results = 2; /* Calculate the offset */ $from = (($page * $max_results) - $max_results); /* Query the db for total results. You need to edit the sql to fit your needs */ $result = mysql_query("select title from topics"); $total_results = mysql_num_rows($result); $total_pages = ceil($total_results / $max_results); $pagination = ''; /* Create a PREV link if there is one */ if($page > 1) { $pagination .= '< a hr_ef="?page='.$prev.'">Previous</a> '; } /* Loop through the total pages */ for($i = 1; $i <= $total_pages; $i++) { if(($page) == $i) { $pagination .= $i; } else { $pagination .= '< a hr_ef="index.php?page='.$i.'">'.$i.'</a>'; } } /* Print NEXT link if there is one */ if($page < $total_pages) { $pagination .= '< a hr_ef="?page='.$next.'"> Next</a>'; } /* Now we have our pagination links in a variable($pagination) ready to print to the page. I pu it in a variable because you may want to show them at the top and bottom of the page */ /* Below is how you query the db for ONLY the results for the current page */ $result=mysql_query("select * from topics LIMIT $from, $max_results "); while ($i = mysql_fetch_array($result)) { echo $i['title'].'<br />'; } echo $pagination; ?>

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  • Get SEO friendly URLS with Rails without method_missing?

    - by tesmar
    Hi all, Currently we are using method_missing to catch for calls to SEO friendly actions in our controllers rather than creating actions for every conceivable value for a variable. What we want are URLS like this: /students/BobSmith and NOT /students/show/342 IS there a cleaner solution than method_missing? Thank you!

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  • How to assign a value of a property to a var ONLY if the object isn't null

    - by Blankman
    In my code, is there a shorthand that I can use to assign a variable the value of a object's property ONLY if the object isn't null? string username = SomeUserObject.Username; // fails if null I know I can do a check like if(SomeUserObject != null) but I think I saw a shorthand for this kind of test. I tried: string username = SomeUserObject ?? "" : SomeUserObject.Username; But that doesn't work.

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  • What does static and IOException mean?

    - by Brian
    I just had a test on java and we had to give the definition of 1) Static: 2) IOExcepion: What I said for static was...a static method is used to define a method as a class method. And I got it wrong so I asked my teacher and he said he wants the actually definition of static not a static method, class or variable just static. Can someone tell me the definition of this and for IOException please Thanks.

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  • Naming guidelines with C#.

    - by VansFannel
    Hello! I have this class: class DoSomething { private int timesDone; ... } Which is the right way to named variable 'timesDone'? Sometimes I see named as m_timesDone. Is this correct? Where I can find information about naming guidelines? Thank you!

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  • Efficient way to build a MySQL update query in Python

    - by ensnare
    I have a class variable called attributes which lists the instance variables I want to update in a database: attributes = ['id', 'first_name', 'last_name', 'name', 'name_url', 'email', 'password', 'password_salt', 'picture_id'] Each of the class attributes are updated upon instantiation. I would like to loop through each of the attributes and build a MySQL update query in the form of: UPDATE members SET id = self._id, first_name = self._first name ... Thanks.

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  • Session or Query

    - by Khou
    Should I store the user's ID, name & email address in a session variable or should I query for the user's user's ID, name & email address everytime i need to use it?

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  • SQL swap field values

    - by Silence
    I have a SQL table (MYSQL 4.0 to be precise) composed of the following : int no (primary) int field1 int field2 I would like to swap the values of field1 with the values of field2 and vice-versa. Ex.: 1;2.5;3.76 becomes 1;3.76;2.5 I need a swapping temporary variable of some sort. But I don't think I can use something like Set @var1 = field1 inside my update statement. And I don't think altering the table to add a temporary column is my best best either.

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