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  • Removing a node from a linked list

    - by lost_with_coding
    I would like to create a delete_node function that deletes the node at the location in the list as a count from the first node. So far this is the code I have: class node: def __init__(self): self.data = None # contains the data self.next = None # contains the reference to the next node class linked_list: def __init__(self): self.cur_node = None def add_node(self, data): new_node = node() # create a new node new_node.data = data new_node.next = self.cur_node # link the new node to the 'previous' node. self.cur_node = new_node # set the current node to the new one. def list_print(self): node = ll.cur_node while node: print node.data node = node.next def delete_node(self,location): node = ll.cur_node count = 0 while count != location: node = node.next count+=1 delete node ll = linked_list() ll.add_node(1) ll.add_node(2) ll.add_node(3) ll.list_print()

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  • Convert object to DateRange

    - by user655832
    I'm querying an underlying PostgreSQL database using Pandas 0.8. Pandas is returning the DataFrame properly but the underlying timestamp column in my database is being returned as a generic "object" type in Pandas. As I would eventually like to seasonal normalization of my data I am curious as to how to convert this generic "object" column to something that is appropriate for analysis. Here is my current code to retrieve the data: # get records from db example import pandas.io.sql as psql import psycopg2 # define query to get all subs created this year QRY = """ select i i, i * random() f, case when random() > 0.5 then true else false end t, (current_date - (i*random())::int)::timestamp with time zone tsz from generate_series(1,1000) as s(i) order by 4 ; """ CONN_STRING = "host='localhost' port=5432 dbname='postgres' user='postgres'" # connect to db conn = psycopg2.connect(CONN_STRING) # get some data set index on relid column df = psql.frame_query(QRY, con=conn) print "Row count retrieved: %i" % (len(df),) Thanks for any help you can render. M

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  • Images to video - converting to IplImage makes video blue

    - by user891908
    I want to create a video from images using opencv. The strange problem is that if i will write image (bmp) to disk and then load (cv.LoadImage) it it renders fine, but when i try to load image from StringIO and convert it to IplImage, it turns video to blue. Heres the code: import StringIO output = StringIO.StringIO() FOREGROUND = (0, 0, 0) TEXT = 'MY TEXT' font_path = 'arial.ttf' font = ImageFont.truetype(font_path, 18, encoding='unic') text = TEXT.decode('utf-8') (width, height) = font.getsize(text) # Create with background with place for text w,h=(600,600) contentimage=Image.open('0.jpg') background=Image.open('background.bmp') x, y = contentimage.size # put content onto background background.paste(contentimage,(((w-x)/2),0)) draw = ImageDraw.Draw(background) draw.text((0,0), text, font=font, fill=FOREGROUND) pi = background pi.save(output, "bmp") #pi.show() #shows image in full color output.seek(0) pi= Image.open(output) print pi, pi.format, "%dx%d" % pi.size, pi.mode cv_im = cv.CreateImageHeader(pi.size, cv.IPL_DEPTH_8U, 3) cv.SetData(cv_im, pi.tostring()) print pi.size, cv.GetSize(cv_im) w = cv.CreateVideoWriter("2.avi", cv.CV_FOURCC('M','J','P','G'), 1,(cv.GetSize(cv_im)[0],cv.GetSize(cv_im)[1]), is_color=1) for i in range(1,5): cv.WriteFrame(w, cv_im) del w

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  • Google App Engine - Document Editor Creation/Tap Into Google Docs?

    - by Josh Patton
    What is the best way to create a custom document editor in GAE? I'm making a website meant for a School Robotics Club (With support for any other organization - DRY). We currently use Google services for online collaboration, I'm wondering if there is a way to tap into Google Docs and allow users to edit a Google Document without using Google Accounts or the Google Doc interface. If that is not possible (I've researched and I don't think it is), what is the best way to make a document editor? I want it completely on the website I'm creating, so I'm assuming just some javascript editor like TinyMCE + Ajax + Datastore. Is their anything that replicates Google Doc's/Microsoft Offices's/OpenOffice.org's feature set as far as fonts, spacing, alignment, justification, etc.?

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  • Get particular row as series from pandas dataframe

    - by Pratyush
    How do we get a particular filtered row as series? Example dataframe: >>> df = pd.DataFrame({'date': [20130101, 20130101, 20130102], 'location': ['a', 'a', 'c']}) >>> df date location 0 20130101 a 1 20130101 a 2 20130102 c I need to select the row where location is c as a series. I tried: row = df[df["location"] == "c"].head(1) # gives a dataframe row = df.ix[df["location"] == "c"] # also gives a dataframe with single row In either cases I can't the row as series.

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  • Writing a post search algorithm.

    - by MdaG
    I'm trying to write a free text search algorithm for finding specific posts on a wall (similar kind of wall as Facebook uses). A user is suppose to be able to write some words in a search field and get hits on posts that contain the words; with the best match on top and then other posts in decreasing order according to match score. I'm using the edit distance (Levenshtein) "e(x, y) = e" to calculate the score for each post when compared to the query word "x" and post word "y" according to: score(x, y) = 2^(2 - e)(1 - min(e, |x|) / |x|) Each word in a post contributes to the total score for that specific post. This approach seems to work well when the posts are of roughly the same size, but sometime certain large posts manages to rack up score solely on having a lot of words in them while in practice not being relevant to the query. Am I approaching this problem in the wrong way or is there some way to normalize the score that I haven't thought of?

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  • Simple numpy question

    - by dassouki
    I can't get this snippet to work: #base code A = array([ [ 1, 2, 10 ], [ 1, 3, 20 ], [ 1, 4, 30 ], [ 2, 1, 15 ], [ 2, 3, 25 ], [ 2, 4, 35 ], [ 3, 1, 17 ], [ 3, 2, 27 ], [ 3, 4, 37 ], [ 4, 1, 13 ], [ 4, 2, 23 ], [ 4, 3, 33 ] ]) # Number of zones zones = unique1d(A[:,0]) for origin in zones: for destination in zones: if origin != destination: A_ik = A[(A[:,0] == origin & A[:,1] == destination), 2]

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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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  • split twice in the same expression?

    - by UcanDoIt
    Imagine I have the following: inFile = "/adda/adas/sdas/hello.txt" # that instruction give me hello.txt Name = inFile.name.split("/") [-1] # that one give me the name I want - just hello Name1 = Name.split(".") [0] Is there any chance to simplify that doing the same job in just one expression?

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  • How to reset Scrapy parameters? (always running under same parameters)

    - by Jean Ventura
    I've been running my Scrapy project with a couple of accounts (the project scrapes a especific site that requieres login credentials), but no matter the parameters I set, it always runs with the same ones (same credentials). I'm running under virtualenv. Is there a variable or setting I'm missing? Edit: It seems that this problem is Twisted related. Even when I run: scrapy crawl -a user='user' -a password='pass' -o items.json -t json SpiderName I still get an error saying: ERROR: twisted.internet.error.ReactorNotRestartable And all the information I get, is the last 'succesful' run of the spider.

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  • How do I create a Django ModelForm, so that it's fields are sometimes required, sometimes not?

    - by Graf
    Ok, here is the question. Imagine I have a ModelForm which have only two fields. like this one: class ColorForm(forms.Form): color_by_name = forms.CharField() color = forms.IntegerField(widget = forms.Select(choices=COLOR_CHOICES)) So a user can either input a color name, a choose it from a list. Color is required, but that doesn't mean, that user should enter it manually. There do I put validation, so that my code checks if user selected color in dropdownlist and if not then he should write it manually?

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  • Why doesn't this list comprehension do what I expect it to do?

    - by Az
    The original list project_keys = sorted(projects.keys()) is [101, 102, 103, 104, 105, 106, 107, 108, 109, 110] where the following projects were deemed invalid this year: 108, 109, 110. Thus: for project in projects.itervalues(): # The projects dictionary is mapped to the Project class if project.invalid: # Where invalid is a Bool parameter in the Project class project_keys.remove(project.proj_id) print project_keys This will return a list of integers (which are project id's) as such: [101, 102, 103, 104, 105, 106, 107] Sweet. Now, I wanted it try the same thing using a list comprehension. project_keys = [project_keys.remove(project.proj_id) for project in projects.itervalues() if project.invalid print project_keys This returns: [None, None, None] So I'm populating a list with the same number as the removed elements but they're Nones? Can someone point out what I'm doing wrong? Additionally, why would I use a list comprehension over the for-if block at the top? Conciseness? Looks nicer?

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  • In SqlAlchemy, how to ignore m2m relationship attributes when merge?

    - by ablmf
    There is a m2m relation in my models, User and Role. I want to merge a role, but i DO NOT want this merge has any effect on user and role relation-ship. Unfortunately, for some complicate reason, role.users if not empty. I tried to set role.users = None, but SA complains None is not a list. At this moment, I use sqlalchemy.orm.attributes.del_attribute, but I don't know if it's provided for this purpose.

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  • Does this introduce security vulnerabilities?

    - by mcmt
    I don't think I'm missing anything. Then again I'm kind of a newbie. def GET(self, filename): name = urllib.unquote(filename) full = path.abspath(path.join(STATIC_PATH, filename)) #Make sure request is not tricksy and tries to get out of #the directory, e.g. filename = "../.ssh/id_rsa". GET OUTTA HERE assert full[:len(STATIC_PATH)] == STATIC_PATH, "bad path" return open(full).read()

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  • My QFileSystemModel doesn't work as expected in PyQt

    - by Skilldrick
    I'm learning the Qt Model/View architecture at the moment, and I've found something that doesn't work as I'd expect it to. I've got the following code (adapted from Qt Model Classes): from PyQt4 import QtCore, QtGui model = QtGui.QFileSystemModel() parentIndex = model.index(QtCore.QDir.currentPath()) print model.isDir(parentIndex) #prints True print model.data(parentIndex).toString() #prints name of current directory childIndex = model.index(0, 0, parentIndex) print model.data(childIndex).toString() rows = model.rowCount(parentIndex) print rows #prints 0 (even though the current directory has directory and file children) The question: Is this a problem with PyQt, have I just done something wrong, or am I completely misunderstanding QFileSystemModel? According to the documentation, model.rowCount(parentIndex) should return the number of children in the current directory. The QFileSystemModel docs say that it needs an instance of a Gui application, so I've also placed the above code in a QWidget as follows, but with the same result: import sys from PyQt4 import QtCore, QtGui class Widget(QtGui.QWidget): def __init__(self, parent=None): QtGui.QWidget.__init__(self, parent) model = QtGui.QFileSystemModel() parentIndex = model.index(QtCore.QDir.currentPath()) print model.isDir(parentIndex) print model.data(parentIndex).toString() childIndex = model.index(0, 0, parentIndex) print model.data(childIndex).toString() rows = model.rowCount(parentIndex) print rows def main(): app = QtGui.QApplication(sys.argv) widget = Widget() widget.show() sys.exit(app.exec_()) if __name__ == '__main__': main()

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  • How to override inner class methods if the inner class is defined as a property of the top class

    - by Maddy
    I have a code snippet like this class A(object): class b: def print_hello(self): print "Hello world" b = property(b) And I want to override the inner class b (please dont worry about the lowercase name) behaviour. Say, I want to add a new method or I want to change an existing method, like: class C(A): class b(A.b): def print_hello(self): print "Inner Class: Hello world" b = property(b) Now if I create C's object as c = C(), and call c.b I get TypeError: 'property' object is not callable error. How would I get pass this and call print_hello of the extended inner class? Disclaimer: I dont want to change the code for A class.

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  • class inheretence of a attribute which is itself a class

    - by alex
    i have a class which inherets a attribute from a super-class. this attribute is a class itself. class classA(superClass): def func(self,x): if self.attributeB is None: do somthing and in the other class i have class superClass: self.attributB = classB() i get the error AttributeError: class classA has no attribute 'attributeB' when i access the attribute like i showed but if on command line i can see it works, x = classA() x.attributeB is None True so the test works. whats going on in the above code?

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  • slicing 2d numpy array

    - by MedicalMath
    I have a 2d numpy array called FilteredOutput that has 2 columns and 10001 rows, though the number of rows is a variable. I am trying to take the 2nd column of FilteredOutput and use it to populate a new 1d numpy array called timeSeriesArray using the following line of code: timeSeriesArray=p.array(FilteredOutput[:,0]) I got this syntax from the following link. But the problem is that I am getting the following error message: TypeError: list indices must be integers, not tuple Can anyone show me the proper syntax for populating the 1d array timeSeriesArray with the contents of the second column of the 2d array FilteredOutput?

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  • Histogram in Matplotlib with input file

    - by Arkapravo
    I wish to make a Histogram in Matplotlib from an input file containing the raw data (.txt). I am facing issues in referring to the input file. I guess it should be a rather small program. Any Matplotlib gurus, any help ? I am not asking for the code, some inputs should put me on the right way !

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