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  • Count the number of objects in an Image

    - by kunjaan
    I am investigating the possibility of image processing to identify certain objects and also count them in an image. I will be given a picture and I need to identify the number of boxes present in that image. Does anybody have any experience with any Machine Vision/ Image Processing libraries like ImageJ, Fiji, JAI, jMagick ,Java Vision Toolkit? Which do you think is best suited for the job? What do you guys suggest? If the APIs can be used from Java, it would be better. Thank you. Edit: I am dealing with warehouse brown boxes. Yes I am talking about regular photos. The source is usually a mobile phone picture.

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  • Image does not update when file name remains the same in XCode 3.1.2

    - by vman049
    Hi Everyone, I'm using XCode version 3.1.2 and am developing for iPhone using the Simulator with iOS 2.2.1 on Leopard. I had an image file named "img.jpg" in my project which I decided to switch for a different file. After adding the new file into the XCode Resources folder, I removed the first file and renamed the new file to the same name as the previous one, "img.jpg." When I run my program, however, the Simulator loads the old image instead of the new one, even though the old one has been deleted from disk (not just the reference). I tried changing the name of the file to "img2.jpg," and it worked like it should - loading the new image, but I want to keep the name "img.jpg." I ran a search with Spotlight for "img.jpg" to see if there was another copy stored somewhere that XCode was using, but it only returned my new image file. I have tried uninstalling the app from the Simulator and running the application again, but that also does not fix the problem. What must I do for XCode to recognize that I want to use the new image file and not the old one? Thanks for your help!!

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  • Pop up to save image in asp.net

    - by Zerotoinfinite
    Hi All, I am using asp.net 3.5 and C#. I have a image which I want user can download. Like, there would be a download button or link. When user click on this link he will be prompted with a pop up to save that image to his desktop. I have tried with <a href ="path" > </a> but it is opening the image in other page, I want user to be prompted to either save or view the image, please help Thanks in advance

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  • Java - Image encoding in XML

    - by Hoopla
    Hi everyone, I thought I would find a solution to this problem relatively easily, but here I am calling upon the help from ye gods to pull me out of this conundrum. So, I've got an image and I want to store it in an XML document using Java. I have previously achieved this in VisualBasic by saving the image to a stream, converting the stream to an array, and then VB's xml class was able to encode the array as a base64 string. But, after a couple of hours of scouring the net for an equivalent solution in Java, I've come back empty handed. The only success I have had has been by: import it.sauronsoftware.base64.*; import java.awt.image.BufferedImage; import org.w3c.dom.*; ... BufferedImage img; Element node; ... java.io.ByteArrayOutputStream os = new java.io.ByteArrayOutputStream(); ImageIO.write(img, "png", os); byte[] array = Base64.encode(os.toByteArray()); String ss = arrayToString(array, ","); node.setTextContent(ss); ... private static String arrayToString(byte[] a, String separator) { StringBuffer result = new StringBuffer(); if (a.length > 0) { result.append(a[0]); for (int i=1; i<a.length; i++) { result.append(separator); result.append(a[i]); } } return result.toString(); } Which is okay I guess, but reversing the process to get it back to an image when I load the XML file has proved impossible. If anyone has a better way to encode/decode an image in an XML file, please step forward, even if it's just a link to another thread that would be fine. Cheers in advance, Hoopla.

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  • Show information over image on rollover

    - by Chris
    I want to be able to show information (HTML basically) over an image when the mouse rolls over the image... I know there is a .hover() jQuery function but am unsure how to use it to get the desired effect. Ideally when a user hovers over an image it would "grey out" (e.g. layer of 50% opacity black) with some HTML like a title etc etc. Can someone point me in the right direction or provide sample code Thanks

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  • javascript resize background image

    - by George
    Is it possible to resize a background image on load using javascript? I don't care about dynamically resizing the image according to window size or anything, I just want to take large images and resize them to a specific width and height so that the full image fits inside a specific layout.

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  • Issues with an image link

    - by user1462362
    Two days ago I spontaneously bought myself a domain. The day before that, I hardly even knew what a domain really was. Since then, I've been trying to teach myself HTML for the very first time. Basically what I'm trying to say is, I'm very new - and will probably be poor in my explanations. I just succeeded in making an 'image-button', sorta. It's where I make a button-like image and then use it as navigation on my website (just like a regular link). My issue is that the link 'border' itself is bigger than the image, so you can press an inch outside the image itself and it will work. How do I make the invisible link 'border' the same size as the button? This is my site: http://www.djeveln.com On the test page (djeveln.com/test) is where I test things. There's the button I'm talking about, in case you can't understand my explanation very well. Here's my HTML: Here is the CSS I use for the image position and size: img.TestButton { /* Dette linker til selve størrelsen av knappen (bildet)*/ position: absolute; width: 100px; height: 75px; top: 400px; right: 250px; } Hope you can help me! :P

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  • How can I have a floating image (right aligned) with text that wraps around the image in Android Lay

    - by groomsy
    It's kind of hard to explain, but an example of what I'm wanting to accomplish is like this: Here is some text | image | that is printed | | out in a view and --------- it is wrapped around an image that is floating and right aligned. I thought about generating the layout in html and using a web view, but I need to be able to perform an action when the user clicks on the image. Does anyone have any ideas? Thanks in advance, groomsy

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  • Tracking image views - PHP

    - by RS7
    I'd like for my app to be able to tell if an image hasn't been viewed in the last 30 days and remove it (along with data in the DB associated with it). I know you can have PHP read and output the image dynamically but I've heard its quite taxing on the system. Is there a way to for me to track these hits even when the image is viewed directly? (would htaccess be able to do this?) Thanks in advance.

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  • file_get_contents to image and change quality

    - by Chris
    Hey I have some code that downloads an image from a remote server $data = file_get_contents("$rURL"); I want to then change the quality of this image, but do not want to save it out to a file first, how do I convert $data into an image that I can then use in imagecopyresampled? Thanks

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  • Load image blurred Android

    - by Mira
    I'm trying to create a map for a game through an image, where each black pixel is equivalent to a wall, and yellow to flowers(1) and green grass(0) so far i had this image (50x50): http://i.imgur.com/Ydj9Cp2.png the problem here seems to be that, when i read the image on my code, it get's scaled up to 100x100, even tough i have it on the raw folder. I can't let it scale up or down because that will put noise and blur on the image and then the map won't be readable. here i have my code: (...) Bitmap tab=BitmapFactory.decodeResource(resources, com.example.lolitos2.R.raw.mappixel); //tab=Bitmap.createScaledBitmap(tab, 50, 50, false); Log.e("w", tab.getWidth()+"."+tab.getHeight()); for (int i = 0; i < tab.getWidth(); i++) { for (int j = 0; j < tab.getHeight(); j++) { int x = j; int y = i; switch (tab.getPixel(x, y)) { // se o é uma parede case Color.BLACK: getParedes()[x][y] = new Parede(x, y); break; case Color.GREEN: fundo.add(new Passivo(x,y,0)); break; default: fundo.add(new Passivo(x,y,1)); } } } How can i read my image Map without rescaling it?

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  • not able to write log file to specified path(Microsoft Enterprise Library Logging)

    - by prince23
    hi, i am trying to implement the logging Configuration using Microsoft Enterprise Library Logging class Program { static void Main(string[] args) { LogEntry entry = new LogEntry() { Message = "Hello Ent. Lib. Logging" }; Logger.Write(entry); } } here the entry conyain she details. but these details are not written in the file i web config i have the settings done like this. <?xml version="1.0" encoding="utf-8"?> <configuration> <configSections> <section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /> <section name="exceptionHandling" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Configuration.ExceptionHandlingSettings, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /> <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /> </configSections> <loggingConfiguration name="Logging Application Block" tracingEnabled="true" defaultCategory="General" logWarningsWhenNoCategoriesMatch="true"> <listeners> <add fileName="C:\Inetpub\wwwroot\trace.log" header="----------------------------------------" footer="----------------------------------------" formatter="" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" traceOutputOptions="None" filter="All" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="FlatFile TraceListener" /> <add source="Enterprise Library Logging" formatter="Text Formatter" log="Application" machineName="" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FormattedEventLogTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" traceOutputOptions="None" filter="All" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="Formatted EventLog TraceListener" /> </listeners> <formatters> <add template="Timestamp: {timestamp}&#xD;&#xA;Message: {message}&#xD;&#xA;Category: {category}&#xD;&#xA;Priority: {priority}&#xD;&#xA;EventId: {eventid}&#xD;&#xA;Severity: {severity}&#xD;&#xA;Title:{title}&#xD;&#xA;Machine: {machine}&#xD;&#xA;Application Domain: {appDomain}&#xD;&#xA;Process Id: {processId}&#xD;&#xA;Process Name: {processName}&#xD;&#xA;Win32 Thread Id: {win32ThreadId}&#xD;&#xA;Thread Name: {threadName}&#xD;&#xA;Extended Properties: {dictionary({key} - {value}&#xD;&#xA;)}" type="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="Text Formatter" /> </formatters> <categorySources> <add switchValue="All" name="General"> <listeners> <add name="Formatted EventLog TraceListener" /> </listeners> </add> </categorySources> <specialSources> <allEvents switchValue="All" name="All Events" /> <notProcessed switchValue="All" name="Unprocessed Category" /> <errors switchValue="All" name="Logging Errors &amp; Warnings"> <listeners> <add name="Formatted EventLog TraceListener" /> </listeners> </errors> </specialSources> </loggingConfiguration> <exceptionHandling> <exceptionPolicies> <add name="Exception Policy"> <exceptionTypes> <add type="System.Exception, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" postHandlingAction="NotifyRethrow" name="Exception" /> </exceptionTypes> </add> </exceptionPolicies> </exceptionHandling> </configuration> i am trying by best to solve this from past 2 days. if any one knw what is the issue here. why my log file is not written in the specified path. and even the details of log are not written in the file path fileName="C:\Inetpub\wwwroot\trace.log"

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  • Python RSS Feeder + Jquery RSS Reader

    - by Panther24
    I'm trying to implement an RSS Feeder in python using PyRSS2Gen and it created an XML file. Now in jQuery I'm using Google Ajax API's RSS reader and trying to read it. I get an error saying something is wrong. I'm unable to figure out the issue. I've checked some documentation but not able to get it. This is how my xml file looks: <rss version="2.0"> <channel> <title>Andrew's PyRSS2Gen feed</title> <link> http://www.dalkescientific.com/Python/PyRSS2Gen.html </link> <description> The latest news about PyRSS2Gen, a Python library for generating RSS2 feeds </description> <lastBuildDate>Fri, 26 Mar 2010 13:10:55 GMT</lastBuildDate> <generator>PyRSS2Gen-1.0.0</generator> <docs>http://blogs.law.harvard.edu/tech/rss</docs> <item> <title>PyRSS2Gen-0.0 released</title> <link> http://www.dalkescientific.com/news/030906-PyRSS2Gen.html </link> <description> Dalke Scientific today announced PyRSS2Gen-0.0, a library for generating RSS feeds for Python. </description> <guid isPermaLink="true"> http://www.dalkescientific.com/news/030906-PyRSS2Gen.html </guid> <pubDate>Sat, 06 Sep 2003 21:31:00 GMT</pubDate> </item> <item> <title>Thoughts on RSS feeds for bioinformatics</title> <link> http://www.dalkescientific.com/writings/diary/archive/2003/09/06/RSS.html </link> <description> One of the reasons I wrote PyRSS2Gen was to experiment with RSS for data collection in bioinformatics. Last year I came across... </description> <guid isPermaLink="true"> http://www.dalkescientific.com/writings/diary/archive/2003/09/06/RSS.html </guid> <pubDate>Sat, 06 Sep 2003 21:49:00 GMT</pubDate> </item> </channel> </rss> And my JS looks like this <!-- ++Begin Dynamic Feed Wizard Generated Code++ --> <!-- // Created with a Google AJAX Search and Feed Wizard // http://code.google.com/apis/ajaxsearch/wizards.html --> <!-- // The Following div element will end up holding the actual feed control. // You can place this anywhere on your page. --> <!-- Google Ajax Api --> <script src="../js/jsapi.js" type="text/javascript"></script> <!-- Dynamic Feed Control and Stylesheet --> <script src="../js/gfdynamicfeedcontrol.js" type="text/javascript"></script> <link rel="stylesheet" type="text/css" href="../css/gfdynamicfeedcontrol.css"> <script type="text/javascript"> function LoadDynamicFeedControl() { var feeds = [ {title: 'Demo', url: 'wcarss.xml' }]; var options = { stacked : false, horizontal : false, title : "" } new GFdynamicFeedControl(feeds, 'feed-control', options); } // Load the feeds API and set the onload callback. google.load('feeds', '1'); google.setOnLoadCallback(LoadDynamicFeedControl); </script> <!-- ++End Dynamic Feed Control Wizard Generated Code++ --> Can some help me and tell me what I'm doing wrong here? NOTE: Does the XML file have to be deployed? Cause currently its in my local machine and I'm trying to just call it.

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  • Python TEA implementation

    - by Gaks
    Anybody knows proper python implementation of TEA (Tiny Encryption Algorithm)? I tried the one I've found here: http://sysadminco.com/code/python-tea/ - but it does not seem to work properly. It returns different results than other implementations in C or Java. I guess it's caused by completely different data types in python (or no data types in fact). Here's the code and an example: def encipher(v, k): y=v[0];z=v[1];sum=0;delta=0x9E3779B9;n=32 w=[0,0] while(n>0): y += (z << 4 ^ z >> 5) + z ^ sum + k[sum & 3] y &= 4294967295L # maxsize of 32-bit integer sum += delta z += (y << 4 ^ y >> 5) + y ^ sum + k[sum>>11 & 3] z &= 4294967295L n -= 1 w[0]=y; w[1]=z return w def decipher(v, k): y=v[0] z=v[1] sum=0xC6EF3720 delta=0x9E3779B9 n=32 w=[0,0] # sum = delta<<5, in general sum = delta * n while(n>0): z -= (y << 4 ^ y >> 5) + y ^ sum + k[sum>>11 & 3] z &= 4294967295L sum -= delta y -= (z << 4 ^ z >> 5) + z ^ sum + k[sum&3] y &= 4294967295L n -= 1 w[0]=y; w[1]=z return w Python example: >>> import tea >>> key = [0xbe168aa1, 0x16c498a3, 0x5e87b018, 0x56de7805] >>> v = [0xe15034c8, 0x260fd6d5] >>> res = tea.encipher(v, key) >>> "%X %X" % (res[0], res[1]) **'70D16811 F935148F'** C example: #include <unistd.h> #include <stdio.h> void encipher(unsigned long *const v,unsigned long *const w, const unsigned long *const k) { register unsigned long y=v[0],z=v[1],sum=0,delta=0x9E3779B9, a=k[0],b=k[1],c=k[2],d=k[3],n=32; while(n-->0) { sum += delta; y += (z << 4)+a ^ z+sum ^ (z >> 5)+b; z += (y << 4)+c ^ y+sum ^ (y >> 5)+d; } w[0]=y; w[1]=z; } int main() { unsigned long v[] = {0xe15034c8, 0x260fd6d5}; unsigned long key[] = {0xbe168aa1, 0x16c498a3, 0x5e87b018, 0x56de7805}; unsigned long res[2]; encipher(v, res, key); printf("%X %X\n", res[0], res[1]); return 0; } $ ./tea **D6942D68 6F87870D** Please note, that both examples were run with the same input data (v and key), but results were different. I'm pretty sure C implementation is correct - it comes from a site referenced by wikipedia (I couldn't post a link to it because I don't have enough reputation points yet - some antispam thing)

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  • Ubuntu: pip not working with python3.4

    - by val_
    Trying to get pip working on my Ubuntu pc. pip seems to be working for python2.7, but not for others. Here's the problem: $ pip Traceback (most recent call last): File "/usr/local/bin/pip", line 9, in <module> load_entry_point('pip==1.4.1', 'console_scripts', 'pip')() File "/usr/local/lib/python3.4/dist-packages/setuptools-1.1.5-py3.4.egg /pkg_resources.py", line 357, in load_entry_point def get_entry_info(dist, group, name): File "/usr/local/lib/python3.4/dist-packages/setuptools-1.1.5-py3.4.egg/pkg_resources.py", line 2394, in load_entry_point break File "/usr/local/lib/python3.4/dist-packages/setuptools-1.1.5-py3.4.egg/pkg_resources.py", line 2108, in load name = some.module:some.attr [extra1,extra2] ImportError: No module named 'pip' $ which pip /usr/local/bin/pip $ python2.7 -m pip //here can be just python, btw Usage: /usr/bin/python2.7 -m pip <command> [options] //and so on... $ python3.4 -m pip /usr/bin/python3.4: No module named pip From the home/user/.pip/pip.log : Exception: Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/pip/basecommand.py", line 122, in main status = self.run(options, args) File "/usr/lib/python2.7/dist-packages/pip/commands/install.py", line 283, in run requirement_set.install(install_options, global_options, root=options.root_path) File "/usr/lib/python2.7/dist-packages/pip/req.py", line 1431, in install requirement.uninstall(auto_confirm=True) File "/usr/lib/python2.7/dist-packages/pip/req.py", line 598, in uninstall paths_to_remove.remove(auto_confirm) File "/usr/lib/python2.7/dist-packages/pip/req.py", line 1836, in remove renames(path, new_path) File "/usr/lib/python2.7/dist-packages/pip/util.py", line 295, in renames shutil.move(old, new) File "/usr/lib/python2.7/shutil.py", line 303, in move os.unlink(src) OSError: [Errno 13] Permission denied: '/usr/bin/pip' There's no /usr/bin/pip btw. How can I fix this issue to work with pip and python 3.4 normally? I am trying to use pycharm, but it's package manager also stucks in this problem. Thanks for attention!

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  • mysqldb interfaceError

    - by Johanna
    I have a very weird probleme with mysqldb (mysql module for python). I have a file with queries for inserting records in tables. If I call the functions from the file, it works just fine. But when I try to call one of the functions from another file it throws me a _mysql_exception.InterfaceError: (0, '') I really don't get what I'm doing wrong here.. I call the function from buildDB.py : import create create.newFormat("HD", 0,0,0) The function newFormat(..) is in create.py (imported) : from Database import Database db = Database() def newFormat(name, width=0, height=0, fps=0): format_query = "INSERT INTO Format (form_name, form_width, form_height, form_fps) VALUES ('"+name+"',"+str(width)+","+str(height)+","+str(fps)+");" db.execute(format_query) And the class Databse is the following : import MySQLdb from MySQLdb.constants import FIELD_TYPE class Database(): def __init__(self): server = "localhost" login = "seq" password = "seqmanager" database = "Sequence" my_conv = { FIELD_TYPE.LONG: int } self.conn = MySQLdb.connection(host=server, user=login, passwd=password, db=database, conv=my_conv) # self.cursor = self.conn.cursor() def close(self): self.conn.close() def execute(self, query): self.conn.query(query) (I put only relevant code) Traceback : Z:\sequenceManager\mysql>python buildDB.py D:\ProgramFiles\Python26\lib\site-packages\MySQLdb\__init__.py:34: DeprecationWa rning: the sets module is deprecated from sets import ImmutableSet INSERT INTO Format (form_name, form_width, form_height, form_fps) VALUES ('HD',0 ,0,0); Traceback (most recent call last): File "buildDB.py", line 182, in <module> create.newFormat("HD") File "Z:\sequenceManager\mysql\create.py", line 52, in newFormat db.execute(format_query) File "Z:\sequenceManager\mysql\Database.py", line 19, in execute self.conn.query(query) _mysql_exceptions.InterfaceError: (0, '') The warning has never been a problem before so I don't think it's related.

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  • Configure Django project in a subdirectory using mod_python. Admin not working.

    - by David
    HI guys. I was trying to configure my django project in a subdirectory of the root, but didn't get things working.(LOcally it works perfect). I followed the django official django documentarion to deploy a project with mod_python. The real problem is that I am getting "Page not found" errors, whenever I try to go to the admin or any view of my apps. Here is my python.conf file located in /etc/httpd/conf.d/ in Fedora 7 LoadModule python_module modules/mod_python.so SetHandler python-program PythonHandler django.core.handlers.modpython SetEnv DJANGO_SETTINGS_MODULE mysite.settings PythonOption django.root /mysite PythonDebug On PythonPath "['/var/www/vhosts/mysite.com/httpdocs','/var/www/vhosts/mysite.com/httpdocs/mysite'] + sys.path" I know /var/www/ is not the best place to put my django project, but I just want to send a demo of my work in progress to my customer, later I will change the location. For example. If I go to www.domain.com/mysite/ I get the index view I configured in mysite.urls. But I cannot access to my app.urls (www.domain.com/mysite/app/) and any of the admin.urls.(www.domain.com/mysite/admin/) Here is mysite.urls: urlpatterns = patterns('', url(r'^admin/password_reset/$', 'django.contrib.auth.views.password_reset', name='password_reset'), (r'^password_reset/done/$', 'django.contrib.auth.views.password_reset_done'), (r'^reset/(?P<uidb36>[0-9A-Za-z]+)-(?P<token>.+)/$', 'django.contrib.auth.views.password_reset_confirm'), (r'^reset/done/$', 'django.contrib.auth.views.password_reset_complete'), (r'^$', 'app.views.index'), (r'^admin/', include(admin.site.urls)), (r'^app/', include('mysite.app.urls')), (r'^photologue/', include('photologue.urls')), ) I also tried changing admin.site.urls with ''django.contrib.admin.urls' , but it didn't worked. I googled a lot to solve this problem and read how other developers configure their django project, but didn't find too much information to deploy django in a subdirectory. I have the admin enabled in INSTALLED_APPS and the settings.py is ok. Please if you have any guide or telling me what I am doing wrong it will be much appreciated. THanks.

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  • Enterprise Library 5.0 Released

    - by Ramaraju
    Microsoft announced the release of Enterprise library 5.0. Enterprise library is set of reusable software components which will help to accelerate the enterprise application development. This version of enterprise library is targeted to support .Net 4.0 version. You can download this at http://www.microsoft.com/downloads/details.aspx?FamilyId=bcb166f7-dd16-448b-a152-9845760d9b4c&displaylang=en Know more about Enterprise library 5.0 here

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  • Solving embarassingly parallel problems using Python multiprocessing

    - by gotgenes
    How does one use multiprocessing to tackle embarrassingly parallel problems? Embarassingly parallel problems typically consist of three basic parts: Read input data (from a file, database, tcp connection, etc.). Run calculations on the input data, where each calculation is independent of any other calculation. Write results of calculations (to a file, database, tcp connection, etc.). We can parallelize the program in two dimensions: Part 2 can run on multiple cores, since each calculation is independent; order of processing doesn't matter. Each part can run independently. Part 1 can place data on an input queue, part 2 can pull data off the input queue and put results onto an output queue, and part 3 can pull results off the output queue and write them out. This seems a most basic pattern in concurrent programming, but I am still lost in trying to solve it, so let's write a canonical example to illustrate how this is done using multiprocessing. Here is the example problem: Given a CSV file with rows of integers as input, compute their sums. Separate the problem into three parts, which can all run in parallel: Process the input file into raw data (lists/iterables of integers) Calculate the sums of the data, in parallel Output the sums Below is traditional, single-process bound Python program which solves these three tasks: #!/usr/bin/env python # -*- coding: UTF-8 -*- # basicsums.py """A program that reads integer values from a CSV file and writes out their sums to another CSV file. """ import csv import optparse import sys def make_cli_parser(): """Make the command line interface parser.""" usage = "\n\n".join(["python %prog INPUT_CSV OUTPUT_CSV", __doc__, """ ARGUMENTS: INPUT_CSV: an input CSV file with rows of numbers OUTPUT_CSV: an output file that will contain the sums\ """]) cli_parser = optparse.OptionParser(usage) return cli_parser def parse_input_csv(csvfile): """Parses the input CSV and yields tuples with the index of the row as the first element, and the integers of the row as the second element. The index is zero-index based. :Parameters: - `csvfile`: a `csv.reader` instance """ for i, row in enumerate(csvfile): row = [int(entry) for entry in row] yield i, row def sum_rows(rows): """Yields a tuple with the index of each input list of integers as the first element, and the sum of the list of integers as the second element. The index is zero-index based. :Parameters: - `rows`: an iterable of tuples, with the index of the original row as the first element, and a list of integers as the second element """ for i, row in rows: yield i, sum(row) def write_results(csvfile, results): """Writes a series of results to an outfile, where the first column is the index of the original row of data, and the second column is the result of the calculation. The index is zero-index based. :Parameters: - `csvfile`: a `csv.writer` instance to which to write results - `results`: an iterable of tuples, with the index (zero-based) of the original row as the first element, and the calculated result from that row as the second element """ for result_row in results: csvfile.writerow(result_row) def main(argv): cli_parser = make_cli_parser() opts, args = cli_parser.parse_args(argv) if len(args) != 2: cli_parser.error("Please provide an input file and output file.") infile = open(args[0]) in_csvfile = csv.reader(infile) outfile = open(args[1], 'w') out_csvfile = csv.writer(outfile) # gets an iterable of rows that's not yet evaluated input_rows = parse_input_csv(in_csvfile) # sends the rows iterable to sum_rows() for results iterable, but # still not evaluated result_rows = sum_rows(input_rows) # finally evaluation takes place as a chain in write_results() write_results(out_csvfile, result_rows) infile.close() outfile.close() if __name__ == '__main__': main(sys.argv[1:]) Let's take this program and rewrite it to use multiprocessing to parallelize the three parts outlined above. Below is a skeleton of this new, parallelized program, that needs to be fleshed out to address the parts in the comments: #!/usr/bin/env python # -*- coding: UTF-8 -*- # multiproc_sums.py """A program that reads integer values from a CSV file and writes out their sums to another CSV file, using multiple processes if desired. """ import csv import multiprocessing import optparse import sys NUM_PROCS = multiprocessing.cpu_count() def make_cli_parser(): """Make the command line interface parser.""" usage = "\n\n".join(["python %prog INPUT_CSV OUTPUT_CSV", __doc__, """ ARGUMENTS: INPUT_CSV: an input CSV file with rows of numbers OUTPUT_CSV: an output file that will contain the sums\ """]) cli_parser = optparse.OptionParser(usage) cli_parser.add_option('-n', '--numprocs', type='int', default=NUM_PROCS, help="Number of processes to launch [DEFAULT: %default]") return cli_parser def main(argv): cli_parser = make_cli_parser() opts, args = cli_parser.parse_args(argv) if len(args) != 2: cli_parser.error("Please provide an input file and output file.") infile = open(args[0]) in_csvfile = csv.reader(infile) outfile = open(args[1], 'w') out_csvfile = csv.writer(outfile) # Parse the input file and add the parsed data to a queue for # processing, possibly chunking to decrease communication between # processes. # Process the parsed data as soon as any (chunks) appear on the # queue, using as many processes as allotted by the user # (opts.numprocs); place results on a queue for output. # # Terminate processes when the parser stops putting data in the # input queue. # Write the results to disk as soon as they appear on the output # queue. # Ensure all child processes have terminated. # Clean up files. infile.close() outfile.close() if __name__ == '__main__': main(sys.argv[1:]) These pieces of code, as well as another piece of code that can generate example CSV files for testing purposes, can be found on github. I would appreciate any insight here as to how you concurrency gurus would approach this problem. Here are some questions I had when thinking about this problem. Bonus points for addressing any/all: Should I have child processes for reading in the data and placing it into the queue, or can the main process do this without blocking until all input is read? Likewise, should I have a child process for writing the results out from the processed queue, or can the main process do this without having to wait for all the results? Should I use a processes pool for the sum operations? If yes, what method do I call on the pool to get it to start processing the results coming into the input queue, without blocking the input and output processes, too? apply_async()? map_async()? imap()? imap_unordered()? Suppose we didn't need to siphon off the input and output queues as data entered them, but could wait until all input was parsed and all results were calculated (e.g., because we know all the input and output will fit in system memory). Should we change the algorithm in any way (e.g., not run any processes concurrently with I/O)?

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  • draw circle PIL - python

    - by ariel
    Hi I am looking for a command that will draw a circle on an existing image. im=Image.open(path) looking for a function that will draw a coloured circle with radious r and center(x,y) thanks for any help provided Ariel

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