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  • Extract points within a shape from a raster

    - by user308827
    Hi, I have a raster file (basically 2D array) with close to a million points. I am trying to extract a circle from the raster (and all the points that lie within the circle. Using ArcGIS is exceedingly slow for this. Can anyone suggest any image processing library that is both easy to learn and powerful and quick enough for something like this? Thanks!

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  • How to get to the key name of a referenced entity property from an entity instance without a datastore read in google app engine?

    - by Sumeet Pareek
    Consider I have the following models - class Team(db.Model): # say I have just 5 teams name = db.StringProperty() class Player(db.Model): # say I have thousands of players name = db.StringProperty() team = db.ReferenceProperty(Team, collection_name="player_set") Key name for each Team entity = 'team_' , and for each Player entity = 'player_' By some prior arrangement I have a Team entity's (key_name, name) mapping available to me. For example (team_01, United States Of America), (team_02, Russia) etc I have to show all the players and their teams on a page. One way of doing this would be - players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(player.team.name) #This is a total of 1x1000 = 1000 DB reads That is a 1001 DB reads for a silly thing. The interesting part is that when I do a db.to_dict() on players, it shows that for every player in that list there is 'name' of the player and there is the 'key_name' of the team available too. So how can I do the below ?? players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(team_list[player.<SOME WAY OF GETTING TEAM KEY NAME>]) # Here 'team_list' already has (key_name, name) for all 5 teams I have been struggling with this for a long time. Have read every available documentation. I could just hug the person that can help me here :-) Disclaimer: The above problem description is not a real scenario. It is a simplified arrangement that represents my problem exactly. I have run into it in a rater complex and big GAE appication.

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  • how to model a follower stream in appengine?

    - by molicule
    I am trying to design tables to buildout a follower relationship. Say I have a stream of 140char records that have user, hashtag and other text. Users follow other users, and can also follow hashtags. I am outlining the way I've designed this below, but there are two limitaions in my design. I was wondering if others had smarter ways to accomplish the same goal. The issues with this are The list of followers is copied in for each record If a new follower is added or one removed, 'all' the records have to be updated. The code class HashtagFollowers(db.Model): """ This table contains the followers for each hashtag """ hashtag = db.StringProperty() followers = db.StringListProperty() class UserFollowers(db.Model): """ This table contains the followers for each user """ username = db.StringProperty() followers = db.StringListProperty() class stream(db.Model): """ This table contains the data stream """ username = db.StringProperty() hashtag = db.StringProperty() text = db.TextProperty() def save(self): """ On each save all the followers for each hashtag and user are added into a another table with this record as the parent """ super(stream, self).save() hfs = HashtagFollowers.all().filter("hashtag =", self.hashtag).fetch(10) for hf in hfs: sh = streamHashtags(parent=self, followers=hf.followers) sh.save() ufs = UserFollowers.all().filter("username =", self.username).fetch(10) for uf in ufs: uh = streamUsers(parent=self, followers=uf.followers) uh.save() class streamHashtags(db.Model): """ The stream record is the parent of this record """ followers = db.StringListProperty() class streamUsers(db.Model): """ The stream record is the parent of this record """ followers = db.StringListProperty() Now, to get the stream of followed hastags indexes = db.GqlQuery("""SELECT __key__ from streamHashtags where followers = 'myusername'""") keys = [k,parent() for k in indexes[offset:numresults]] return db.get(keys) Is there a smarter way to do this?

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  • Need a workaround to filter on related model and aggregated fields in Django

    - by parxier
    I opened a ticket for this problem. In a nutshell here is my model: class Plan(models.Model): cap = models.IntegerField() class Phone(models.Model): plan = models.ForeignKey(Plan, related_name='phones') class Call(models.Model): phone = models.ForeignKey(Phone, related_name='calls') cost = models.IntegerField() I want to run a query like this one: Phone.objects.annotate(total_cost=Sum('calls__cost')).filter(total_cost__gte=0.5*F('plan__cap')) Unfortunately Django generates bad SQL: SELECT "app_phone"."id", "app_phone"."plan_id", SUM("app_call"."cost") AS "total_cost" FROM "app_phone" INNER JOIN "app_plan" ON ("app_phone"."plan_id" = "app_plan"."id") LEFT OUTER JOIN "app_call" ON ("app_phone"."id" = "app_call"."phone_id") GROUP BY "app_phone"."id", "app_phone"."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan"."cap" and errors with: ProgrammingError: column "app_plan.cap" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ...."plan_id" HAVING SUM("app_call"."cost") >= 0.5 * "app_plan".... Is there any workaround apart from running raw SQL?

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  • Use Regular expression with fileinput

    - by chrissygormley
    Hello, I am trying to replace a variable stored in another file using regular expression. The code I have tried is: r = re.compile(r"self\.uid\s*=\s*('\w{12})'") for line in fileinput.input(['file.py'], inplace=True): print line.replace(r.match(line), sys.argv[1]), The format of the variable in the file is: self.uid = '027FC8EBC2D1' I am trying to pass in a parameter in this format and use regular expression to verify that the sys.argv[1] is correct format and to find the variable stored in this file and replace it with the new variable. Can anyone help. Thanks for the help.

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  • How different protocols interact with eachother in Twisted

    - by stsupermouse
    The scenario I want two different protocols interact with each other is as below: A and B is two different protocols. First A will interact with the server and retrieve some values. Only after A finishes retrieving the values , B will start to interact with the server. Now my problem is that is there an elegant way to initial B when A retrieves the values. Currently I just initial B in A's data process function. But i don't think that this is an elegant way. What I mean an elegant way is that the initialization of B is done by a flow controller or something like that, but not another protocol. Is there an elegant way? such using defered or any other things. I'm just new to twisted, not knowing very much about defered.... Thank you very much!

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  • has any tools easy to download or uploaed data from gae ..

    - by zjm1126
    i find this: http://aralbalkan.com/1784 but it is : Gaebar is an easy-to-use, standalone Django application that you can plug in to your existing Google App Engine Django or app-engine-patch-based Django applications on Google App Engine to give them datastore backup and restore functionality. my app is not based on django,so did you know any tools esay to do this . thanks

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  • Jython java call throws exception asking for 2 args when only one arg is coded

    - by clutch
    I have an Java method I want to call within my Jython servlet running on tomcat5. It looks like this: @SuppressWarnings("unchecked") public School loadByName(String name) { List<School> school; school = getHibernateTemplate().find("from " + getPersistentClass().getName() + " where name = ?", name); return uniqueResult(school); } I call it in Jython using: foobar = SchoolDAOHibernate.loadByName('Univeristy') It throws an error that says loadByName() expects 2 args; got 1. What other argument could it be looking for?

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  • SQLAlchemy: who is in charge of the "session"? ( and how to unit-test with sessions )

    - by Nick Perkins
    I need some guidance on how to use session objects with SQLAlchemy, and how to organize Unit Tests of my mapped objects. What I would like to able to do is something like this: thing = BigThing() # mapped object child = thing.new_child() # create and return a related object thing.save() # will also save the child object In order to achieve this, I was thinking of having the BigThing actually add itself ( and it's children ) to the database -- but maybe this not a good idea? One reason to add objects as soon as possible is Automatic id values that are assigned by the database -- the sooner they are available, the fewer problems there are ( right? ) What is the best way to manage session objects? Who is in charge of the session? Should it be created only when required? or saved for a long time? What about Unit Tests for my mapped objects?...how should the session be handled? Is it ever OK to have mapped objects just automatically add themselves to a database? or is that going to lead to trouble?

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  • how can i set the key 'blob-key' about BlobStore?

    - by pyleaf
    I use the jquery plugin "uploadify" to upload multiple files to My App(GAE), and then save them with blobstore, but it failed. I debug the code into get_uploads, it seems field.type_options is empty and of course has 'blob-key'. Q: where does the key 'blob-key' come from? thank you!

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  • Right way to return proxy model instance from a base model instance in Django ?

    - by sotangochips
    Say I have models: class Animal(models.Model): type = models.CharField(max_length=255) class Dog(Animal): def make_sound(self): print "Woof!" class Meta: proxy = True class Cat(Animal): def make_sound(self): print "Meow!" class Meta: proxy = True Let's say I want to do: animals = Animal.objects.all() for animal in animals: animal.make_sound() I want to get back a series of Woofs and Meows. Clearly, I could just define a make_sound in the original model that forks based on animal_type, but then every time I add a new animal type (imagine they're in different apps), I'd have to go in and edit that make_sound function. I'd rather just define proxy models and have them define the behavior themselves. From what I can tell, there's no way of returning mixed Cat or Dog instances, but I figured maybe I could define a "get_proxy_model" method on the main class that returns a cat or a dog model. Surely you could do this, and pass something like the primary key and then just do Cat.objects.get(pk = passed_in_primary_key). But that'd mean doing an extra query for data you already have which seems redundant. Is there any way to turn an animal into a cat or a dog instance in an efficient way? What's the right way to do what I want to achieve?

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  • Incremement Page Hit Count in Django

    - by Andrew C
    I have a table with an IntegerField (hit_count), and when a page is visited (ie. http://site/page/3) I want record id 3 'hit_count' column in the database to increment by 1. The query should be like: update table set hit_count = hit_count + 1 where id=3 Can I do this with the standard Django Model conventions? Or should I just write the query by hand? I'm starting a new project, so I am trying to avoid hacks. We'll see how long this lasts! Thanks!

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  • build an API service in Django

    - by Peter
    Hi all, I want to build an API service using Django. A basic workflow goes like this: First, an http request goes to http://mycompany.com/create.py?id=001&callback=http://callback.com. It will create a folder on the server with name 001. Second, if the folder does not exist, it will be created. You get response immediately in XML format. It will look like: <?xml version="1.0" encoding="UTF-8"?> <response> <status> <statusCode>0</statusCode> <message>Success</message> </status> <group id="001"/> </response> Finally, the server will do its job (i.e. creating the folder). After it is done, the server does a callback to the URL provided. Currently, I use return render_to_response('create.xml', {'statusCode': statusCode, 'statusMessage': statusMessage, 'groupId': groupId, }, mimetype = 'text/xml') to send the XML response back. I have an XML template which has statusCode, statusMessage, groupId placeholders. <?xml version="1.0" encoding="UTF-8"?> <response> <status> <statusCode>{{ statusCode }}</statusCode> <message>{{ statusMessage }}</message> </status> {% if not statusCode %} <group id="{{ groupId }}"/> {% endif %} </response> But in this way I have to put step 3 before step 2, because otherwise step 3 will not be executed if it is after return statement. Can somebody give me some suggestions how to do this? Thanks.

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  • Broken if statement

    - by Vladimir Nani
    Maybe I am crazy but how that could be? some == null is always false but debugger goes into if-statement body anyway. Any ideas? I have restarted visual studio I have cleaned every bin/obj folder It is not the case that i don`t understand that WindowsIdentity.GetCurrent() may return null. That was my first idea. var some = new object(); if (some == null) { throw new Exception("hi!"); } else { do(); } My code: private void GetCurrentWindowsIdentity() { var identity = WindowsIdentity.GetCurrent() if (identity == null) { throw new Exception(Errors.IdentityIsNullException); } try { if (CurrentAuthenticationWrapper.AuthenticationType == AuthenticationType.Windows) { CurrentLogin = _identity != null ? _identity.Name : string.Empty; } } catch (Exception ex) { ViewManager.ShowError(ex); } _identity = identity; }

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  • Distance between numpy arrays, columnwise

    - by Jaapsneep
    I have 2 arrays in 2D, where the column vectors are feature vectors. One array is of size F x A, the other of F x B, where A << B. As an example, for A = 2 and F = 3 (B can be anything): arr1 = np.array( [[1, 4], [2, 5], [3, 6]] ) arr2 = np.array( [[1, 4, 7, 10, ..], [2, 5, 8, 11, ..], [3, 6, 9, 12, ..]] ) I want to calculate the distance between arr1 and a fragment of arr2 that is of equal size (in this case, 3x2), for each possible fragment of arr2. The column vectors are independent of each other, so I believe I should calculate the distance between each column vector in arr1 and a collection of column vectors ranging from i to i + A from arr2 and take the sum of these distances (not sure though). Does numpy offer an efficient way of doing this, or will I have to take slices from the second array and, using another loop, calculate the distance between each column vector in arr1 and the corresponding column vector in the slice?

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  • pandas read rotated csv files

    - by EricCoding
    Is there any function in pandas that can directly read a rotated csv file? To be specific, the header information in the first col instead of the first row. For example: A 1 2 B 3 5 C 6 7 and I would like the final DataFrame this way A B C 1 3 5 2 5 7 Of corse we can get around this problem using some data wangling techniques like transpose and slicing. I am wondering there should be a quick way in API but I could not find it.

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  • Change text_factory in Django/sqlite

    - by Krumelur
    I have a django project that uses a sqlite database that can be written to by an external tool. The text is supposed to be UTF-8, but in some cases there will be errors in the encoding. The text is from an external source, so I cannot control the encoding. Yes, I know that I could write a "wrapping layer" between the external source and the database, but I prefer not having to do this, especially since the database already contains a lot of "bad" data. The solution in sqlite is to change the text_factory to something like: lambda x: unicode(x, "utf-8", "ignore") However, I don't know how to tell the Django model driver this.

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  • Iterate with binary structure over numpy array to get cell sums

    - by Curlew
    In the package scipy there is the function to define a binary structure (such as a taxicab (2,1) or a chessboard (2,2)). import numpy from scipy import ndimage a = numpy.zeros((6,6), dtype=numpy.int) a[1:5, 1:5] = 1;a[3,3] = 0 ; a[2,2] = 2 s = ndimage.generate_binary_structure(2,2) # Binary structure #.... Calculate Sum of result_array = numpy.zeros_like(a) What i want is to iterate over all cells of this array with the given structure s. Then i want to append a function to the current cell value indexed in a empty array (example function sum), which uses the values of all cells in the binary structure. For example: array([[0, 0, 0, 0, 0, 0], [0, 1, 1, 1, 1, 0], [0, 1, 2, 1, 1, 0], [0, 1, 1, 0, 1, 0], [0, 1, 1, 1, 1, 0], [0, 0, 0, 0, 0, 0]]) # The array a. The value in cell 1,2 is currently one. Given the structure s and an example function such as sum the value in the resulting array (result_array) becomes 7 (or 6 if the current cell value is excluded). Someone got an idea?

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  • SQLAlchemy: a better way for update with declarative?

    - by hadrien
    I am a SQLAlchemy noob. Let's say I have an user table in declarative mode: class User(Base): __tablename__ = 'user' id = Column(u'id', Integer(), primary_key=True) name = Column(u'name', String(50)) When I know user's id without object loaded into session, I update such user like this: ex = update(User.__table__).where(User.id==123).values(name=u"Bob Marley") Session.execute(ex) I dislike using User.__table__, should I stop worrying with that? Is there a better way to do this? Thanx!

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  • Numpy Matrix keeps giving me an Error,

    - by uberjumper
    Okay this is werid, i keep getting the error, randomly. ValueError: matrix must be 2-dimensional So i tracked it down, and cornered it to basically something like this: a_list = [[(1,100) for _ in range(32)] for _ in range(32)] numpy.matrix(a_list) Whats wrong with this? If i print a_list it is clearly a 2d matrix of tuples, however numpy does not believe so.

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  • Encoding with url and api

    - by user2950824
    So I have this web app set up and running and it works fine for any username that you request, but when i try http://mrcastelo.pythonanywhere.com/lol/euw/Nazaré, it simply doesnt work - the error that I get on the server is the following: iddata= getJSON(urllolbase+region+urlid+username) #SummonerID UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 5: ordinal not in range(128) It is annoying me greatly, I've tried some other threads but none of them came to a fix. The api that I am using (www.legendaryapi.com) does accept this because this works. Any idea on how to fix this?

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  • How do you determine an acceptable response time for App Engine DB requests?

    - by qiq
    According to this discussion of Google App Engine on Hacker News, A DB (read) request takes over 100ms on the datastore. That's insane and unusable for about 90% of applications. How do you determine what is an acceptable response time for a DB read request? I have been using App Engine without noticing any issues with DB responsiveness. But, on the other hand, I'm not sure I would even know what to look for in that regard :)

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  • Increasing figure size in Matplotlib

    - by Anirudh
    I am trying to plot a graph from a distance matrix. The code words fine and gives me a image in 800 * 600 pixels. The image being too small, All the nodes are packed together. I want increase the size of the image. so I added the following line to my code - figure(num=None, figsize=(10, 10), dpi=80, facecolor='w', edgecolor='k') After this all I get is a blank 1000 * 1000 image file. My overall code - import networkx as nx import pickle import matplotlib.pyplot as plt print "Reading from pickle." p_file = open('pickles/names') Names = pickle.load(p_file) p_file.close() p_file = open('pickles/distance') Dist = pickle.load(p_file) p_file.close() G = nx.Graph() print "Inserting Nodes." for n in Names: G.add_node(n) print "Inserting Edges." for i in range(601): for j in range(601): G.add_edge(Names[i],Names[j],weight=Dist[i][j]) print "Drawing Graph." nx.draw(G) print "Saving Figure." #plt.figure(num=None, figsize=(10, 10)) plt.savefig('new.png') print "Success!"

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  • Django choking oddly on some static media

    - by Edan Maor
    My situation: I'm serving static media via Django on my dev machine. On some files that I try and load, I get back this error: Traceback: File "c:\Program Files\Python26\Lib\site-packages\django\core\handlers\base.py" in get_response 92. response = callback(request, *callback_args, **callback_kwargs) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\views.py" in userpage 71. so_user = site.user(userid) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in user 476. u, = self.users((nid,), **kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in users 481. return self._get(User, ids, 'users', kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in _get 471. return self.build(root, typ, coll, kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in build 448. json = self._request(url, kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in _request 422. dump = json.load(data) File "c:\Program Files\Python26\lib\json\__init__.py" in load 264. return loads(fp.read(), Exception Type: AttributeError at /userpage/362498 Exception Value: 'str' object has no attribute 'read' I've traced it to specific files which don't work (by going to their specific urls). Here's the odd part: changing the filename of the files makes them suddenly work. For example, I had a file called 'post.jpg', which gave this error. I renamed it to 'pos.jpg' and it worked. Back to 'post.jpg' and it gives the same error.

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