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  • Python: split a list based on a condition?

    - by Parand
    What's the best way, both aesthetically and from a performance perspective, to split a list of items into multiple lists based on a conditional? The equivalent of: good = [x for x in mylist if x in goodvals] bad = [x for x in mylist if x not in goodvals] is there a more elegant way to do this? Update: here's the actual use case, to better explain what I'm trying to do: # files looks like: [ ('file1.jpg', 33L, '.jpg'), ('file2.avi', 999L, '.avi'), ... ] IMAGE_TYPES = ('.jpg','.jpeg','.gif','.bmp','.png') images = [f for f in files if f[2].lower() in IMAGE_TYPES] anims = [f for f in files if f[2].lower() not in IMAGE_TYPES]

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  • Python - How to pickle yourself?

    - by Mark
    I want my class to implement Save and Load functions which simply do a pickle of the class. But apparently you cannot use 'self' in the fashion below. How can you do this? self = cPickle.load(f) cPickle.dump(self,f,2)

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  • In Python BeautifulSoup How to move tags

    - by JJ
    I have a partially converted XML document in soup coming from HTML. After some replacement and editing in the soup, the body is essentially - <Text...></Text> # This replaces <a href..> tags but automatically creates the </Text> <p class=norm ...</p> <p class=norm ...</p> <Text...></Text> <p class=norm ...</p> and so forth. I need to "move" the <p> tags to be children to <Text> or know how to suppress the </Text>. I want - <Text...> <p class=norm ...</p> <p class=norm ...</p> </Text> <Text...> <p class=norm ...</p> </Text> I've tried using item.insert and item.append but I'm thinking there must be a more elegant solution. for item in soup.findAll(['p','span']): if item.name == 'span' and item.has_key('class') and item['class'] == 'section': xBCV = short_2_long(item._getAttrMap().get('value','')) if currentnode: pass currentnode = Tag(soup,'Text', attrs=[('TypeOf', 'Section'),... ]) item.replaceWith(currentnode) # works but creates end tag elif item.name == 'p' and item.has_key('class') and item['class'] == 'norm': childcdatanode = None for ahref in item.findAll('a'): if childcdatanode: pass newlink = filter_hrefs(str(ahref)) childcdatanode = Tag(soup, newlink) ahref.replaceWith(childcdatanode) Thanks

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  • Double linking array in Python

    - by cdecker
    Since I'm pretty new this question'll certainly sound stupid but I have no idea about how to approach this. I'm trying take a list of nodes and for each of the nodes I want to create an array of predecessors and successors in the ordered array of all nodes. Currently my code looks like this: nodes = self.peers.keys() nodes.sort() peers = {} numPeers = len(nodes) for i in nodes: peers[i] = [self.coordinator] for i in range(0,len(nodes)): peers[nodes[i%numPeers]].append(nodes[(i+1)%numPeers]) peers[nodes[(i+1)%numPeers]].append(nodes[i%numPeers]) # peers[nodes[i%numPeers]].append(nodes[(i+4)%numPeers]) # peers[nodes[(i+4)%numPeers]].append(nodes[i%numPeers]) The last two lines should later be used to create a skip graph, but that's not really important. The problem is that it doesn't really work reliably, sometimes a predecessor or a successor is skipped, and instead the next one is used, and so forth. Is this correct at all or is there a better way to do this? Basically I need to get the array indices with certain offsets from each other. Any ideas?

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  • python- scipy optimization

    - by pear
    In scipy fmin_slsqp (Sequential Least Squares Quadratic Programming), I tried reading the code 'slsqp.py' provided with the scipy package, to find what are the criteria to get the exit_modes 0? I cannot find which statements in the code produce this exit mode? Please help me 'slsqp.py' code as follows, exit_modes = { -1 : "Gradient evaluation required (g & a)", 0 : "Optimization terminated successfully.", 1 : "Function evaluation required (f & c)", 2 : "More equality constraints than independent variables", 3 : "More than 3*n iterations in LSQ subproblem", 4 : "Inequality constraints incompatible", 5 : "Singular matrix E in LSQ subproblem", 6 : "Singular matrix C in LSQ subproblem", 7 : "Rank-deficient equality constraint subproblem HFTI", 8 : "Positive directional derivative for linesearch", 9 : "Iteration limit exceeded" } def fmin_slsqp( func, x0 , eqcons=[], f_eqcons=None, ieqcons=[], f_ieqcons=None, bounds = [], fprime = None, fprime_eqcons=None, fprime_ieqcons=None, args = (), iter = 100, acc = 1.0E-6, iprint = 1, full_output = 0, epsilon = _epsilon ): # Now do a lot of function wrapping # Wrap func feval, func = wrap_function(func, args) # Wrap fprime, if provided, or approx_fprime if not if fprime: geval, fprime = wrap_function(fprime,args) else: geval, fprime = wrap_function(approx_fprime,(func,epsilon)) if f_eqcons: # Equality constraints provided via f_eqcons ceval, f_eqcons = wrap_function(f_eqcons,args) if fprime_eqcons: # Wrap fprime_eqcons geval, fprime_eqcons = wrap_function(fprime_eqcons,args) else: # Wrap approx_jacobian geval, fprime_eqcons = wrap_function(approx_jacobian, (f_eqcons,epsilon)) else: # Equality constraints provided via eqcons[] eqcons_prime = [] for i in range(len(eqcons)): eqcons_prime.append(None) if eqcons[i]: # Wrap eqcons and eqcons_prime ceval, eqcons[i] = wrap_function(eqcons[i],args) geval, eqcons_prime[i] = wrap_function(approx_fprime, (eqcons[i],epsilon)) if f_ieqcons: # Inequality constraints provided via f_ieqcons ceval, f_ieqcons = wrap_function(f_ieqcons,args) if fprime_ieqcons: # Wrap fprime_ieqcons geval, fprime_ieqcons = wrap_function(fprime_ieqcons,args) else: # Wrap approx_jacobian geval, fprime_ieqcons = wrap_function(approx_jacobian, (f_ieqcons,epsilon)) else: # Inequality constraints provided via ieqcons[] ieqcons_prime = [] for i in range(len(ieqcons)): ieqcons_prime.append(None) if ieqcons[i]: # Wrap ieqcons and ieqcons_prime ceval, ieqcons[i] = wrap_function(ieqcons[i],args) geval, ieqcons_prime[i] = wrap_function(approx_fprime, (ieqcons[i],epsilon)) # Transform x0 into an array. x = asfarray(x0).flatten() # Set the parameters that SLSQP will need # meq = The number of equality constraints if f_eqcons: meq = len(f_eqcons(x)) else: meq = len(eqcons) if f_ieqcons: mieq = len(f_ieqcons(x)) else: mieq = len(ieqcons) # m = The total number of constraints m = meq + mieq # la = The number of constraints, or 1 if there are no constraints la = array([1,m]).max() # n = The number of independent variables n = len(x) # Define the workspaces for SLSQP n1 = n+1 mineq = m - meq + n1 + n1 len_w = (3*n1+m)*(n1+1)+(n1-meq+1)*(mineq+2) + 2*mineq+(n1+mineq)*(n1-meq) \ + 2*meq + n1 +(n+1)*n/2 + 2*m + 3*n + 3*n1 + 1 len_jw = mineq w = zeros(len_w) jw = zeros(len_jw) # Decompose bounds into xl and xu if len(bounds) == 0: bounds = [(-1.0E12, 1.0E12) for i in range(n)] elif len(bounds) != n: raise IndexError, \ 'SLSQP Error: If bounds is specified, len(bounds) == len(x0)' else: for i in range(len(bounds)): if bounds[i][0] > bounds[i][1]: raise ValueError, \ 'SLSQP Error: lb > ub in bounds[' + str(i) +'] ' + str(bounds[4]) xl = array( [ b[0] for b in bounds ] ) xu = array( [ b[1] for b in bounds ] ) # Initialize the iteration counter and the mode value mode = array(0,int) acc = array(acc,float) majiter = array(iter,int) majiter_prev = 0 # Print the header if iprint >= 2 if iprint >= 2: print "%5s %5s %16s %16s" % ("NIT","FC","OBJFUN","GNORM") while 1: if mode == 0 or mode == 1: # objective and constraint evaluation requird # Compute objective function fx = func(x) # Compute the constraints if f_eqcons: c_eq = f_eqcons(x) else: c_eq = array([ eqcons[i](x) for i in range(meq) ]) if f_ieqcons: c_ieq = f_ieqcons(x) else: c_ieq = array([ ieqcons[i](x) for i in range(len(ieqcons)) ]) # Now combine c_eq and c_ieq into a single matrix if m == 0: # no constraints c = zeros([la]) else: # constraints exist if meq > 0 and mieq == 0: # only equality constraints c = c_eq if meq == 0 and mieq > 0: # only inequality constraints c = c_ieq if meq > 0 and mieq > 0: # both equality and inequality constraints exist c = append(c_eq, c_ieq) if mode == 0 or mode == -1: # gradient evaluation required # Compute the derivatives of the objective function # For some reason SLSQP wants g dimensioned to n+1 g = append(fprime(x),0.0) # Compute the normals of the constraints if fprime_eqcons: a_eq = fprime_eqcons(x) else: a_eq = zeros([meq,n]) for i in range(meq): a_eq[i] = eqcons_prime[i](x) if fprime_ieqcons: a_ieq = fprime_ieqcons(x) else: a_ieq = zeros([mieq,n]) for i in range(mieq): a_ieq[i] = ieqcons_prime[i](x) # Now combine a_eq and a_ieq into a single a matrix if m == 0: # no constraints a = zeros([la,n]) elif meq > 0 and mieq == 0: # only equality constraints a = a_eq elif meq == 0 and mieq > 0: # only inequality constraints a = a_ieq elif meq > 0 and mieq > 0: # both equality and inequality constraints exist a = vstack((a_eq,a_ieq)) a = concatenate((a,zeros([la,1])),1) # Call SLSQP slsqp(m, meq, x, xl, xu, fx, c, g, a, acc, majiter, mode, w, jw) # Print the status of the current iterate if iprint > 2 and the # major iteration has incremented if iprint >= 2 and majiter > majiter_prev: print "%5i %5i % 16.6E % 16.6E" % (majiter,feval[0], fx,linalg.norm(g)) # If exit mode is not -1 or 1, slsqp has completed if abs(mode) != 1: break majiter_prev = int(majiter) # Optimization loop complete. Print status if requested if iprint >= 1: print exit_modes[int(mode)] + " (Exit mode " + str(mode) + ')' print " Current function value:", fx print " Iterations:", majiter print " Function evaluations:", feval[0] print " Gradient evaluations:", geval[0] if not full_output: return x else: return [list(x), float(fx), int(majiter), int(mode), exit_modes[int(mode)] ]

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  • Python Copy Through Assignment?

    - by Marcus Whybrow
    I would expect that the following code would just initialise the dict_a, dict_b and dict_c dictionaries. But it seams to have a copt through effect: dict_a = dict_b = dict_c = {} dict_c['hello'] = 'goodbye' print dict_a print dict_b print dict_c As you can see the result is as follows: {'hello': 'goodbye'} {'hello': 'goodbye'} {'hello': 'goodbye'} Why does that program give the previous result, When I would expect it to return: {} {} {'hello': 'goodbye'}

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  • Reading Python Documentation for 3rd party modules

    - by Shadyabhi
    I recently downloaded IMDbpy moduele.. When I do, import imdb help(imdb) i dont get the full documentation.. I have to do im = imdb.IMDb() help(im) to see the available methods. I dont like this console interface. Is there any better way of reading the doc. I mean all the doc related to module imdb in one page..

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  • Python Process won't call atexit

    - by Brian M. Hunt
    I'm trying to use atexit in a Process, but unfortunately it doesn't seem to work. Here's some example code: import time import atexit import logging import multiprocessing logging.basicConfig(level=logging.DEBUG) class W(multiprocessing.Process): def run(self): logging.debug("%s Started" % self.name) @atexit.register def log_terminate(): # ever called? logging.debug("%s Terminated!" % self.name) while True: time.sleep(10) @atexit.register def log_exit(): logging.debug("Main process terminated") logging.debug("Main process started") a = W() b = W() a.start() b.start() time.sleep(1) a.terminate() b.terminate() The output of this code is: DEBUG:root:Main process started DEBUG:root:W-1 Started DEBUG:root:W-2 Started DEBUG:root:Main process terminated I would expect that the W.run.log_terminate() would be called when a.terminate() and b.terminate() are called, and the output to be something likeso (emphasis added)!: DEBUG:root:Main process started DEBUG:root:W-1 Started DEBUG:root:W-2 Started DEBUG:root:W-1 Terminated! DEBUG:root:W-2 Terminated! DEBUG:root:Main process terminated Why isn't this working, and is there a better way to log a message (from the Process context) when a Process is terminated? Thank you for your input - it's much appreciated.

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  • Confusion Matrix with number of classified/misclassified instances on it (Python/Matplotlib)

    - by Pinkie
    I am plotting a confusion matrix with matplotlib with the following code: from numpy import * import matplotlib.pyplot as plt from pylab import * conf_arr = [[33,2,0,0,0,0,0,0,0,1,3], [3,31,0,0,0,0,0,0,0,0,0], [0,4,41,0,0,0,0,0,0,0,1], [0,1,0,30,0,6,0,0,0,0,1], [0,0,0,0,38,10,0,0,0,0,0], [0,0,0,3,1,39,0,0,0,0,4], [0,2,2,0,4,1,31,0,0,0,2], [0,1,0,0,0,0,0,36,0,2,0], [0,0,0,0,0,0,1,5,37,5,1], [3,0,0,0,0,0,0,0,0,39,0], [0,0,0,0,0,0,0,0,0,0,38] ] norm_conf = [] for i in conf_arr: a = 0 tmp_arr = [] a = sum(i,0) for j in i: tmp_arr.append(float(j)/float(a)) norm_conf.append(tmp_arr) plt.clf() fig = plt.figure() ax = fig.add_subplot(111) res = ax.imshow(array(norm_conf), cmap=cm.jet, interpolation='nearest') cb = fig.colorbar(res) savefig("confmat.png", format="png") But I want to the confusion matrix to show the numbers on it like this graphic (the right one): http://i48.tinypic.com/2e30kup.jpg How can I plot the conf_arr on the graphic?

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  • python object AttributeError: type object 'Track' has no attribute 'title'

    - by ccwhite1
    I apologize if this is a noob question, but I can't seem to figure this one out. I have defined an object that defines a music track (NOTE: originally had the just ATTRIBUTE vs self.ATTRIBUTE. I edited those values in to help remove confusion. They had no affect on the problem) class Track(object): def __init__(self, title, artist, album, source, dest): """ Model of the Track Object Contains the followign attributes: 'Title', 'Artist', 'Album', 'Source', 'Dest' """ self.atrTitle = title self.atrArtist = artist self.atrAlbum = album self.atrSource = source self.atrDest = dest I use ObjectListView to create a list of tracks in a specific directory ....other code.... self.aTrack = [Track(sTitle,sArtist,sAlbum,sSource, sDestDir)] self.TrackOlv.AddObjects(self.aTrack) ....other code.... Now I want to iterate the list and print out a single value of each item list = self.TrackOlv.GetObjects() for item in list: print item.atrTitle This fails with the error AttributeError: type object 'Track' has no attribute 'atrTitle' What really confuses me is if I highlight a single item in the Object List View display and use the following code, it will correctly print out the single value for the highlighted item list = self.TrackOlv.GetSelectedObject() print list.atrTitle

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  • Python: date, time formatting

    - by TarGz
    I need to generate a local timestamp in a form of YYYYMMDDHHmmSSOHH'mm'. That OHH'mm' is one of +, -, Z and then there are hourhs and minutes followed by '. Please, how do I get such a timestamp, denoting both local time zone and possible daylight saving?

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  • Python - Nested List to Tab Delimited File?

    - by Seafoid
    Hi, I have a nested list comprising ~30,000 sub-lists, each with three entries, e.g., nested_list = [['x', 'y', 'z'], ['a', 'b', 'c']]. I wish to create a function in order to output this data construct into a tab delimited format, e.g., x y z a b c Any help greatly appreciated! Thanks in advance, Seafoid.

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  • Python and Gstreamer

    - by Seif Sallam
    hi, I'm creating a streaming application, using GStreamer with TCP pipeline, and i implemented start, pause, and stop. but the problem is, that i can't seek, i tried to change the playback value from the server side, then i tried on the client side, and Finally tried to change the value on both at the same time, but in all cases it doesn't work. and I even tried to pause the playback then continue but nothing happens. I'm having this problem with the seek and the volume. Any help please, I searched everywhere but i couldn't find anything that worked. this is the code that i use for seeking self.pipeline.seek_simple(gst.FORMAT_TIME, gst.SEEK_FLAG_FLUSH, time)

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  • Python halts while iteratively processing my 1GB csv file

    - by Dan
    I have two files: metadata.csv: contains an ID, followed by vendor name, a filename, etc hashes.csv: contains an ID, followed by a hash The ID is essentially a foreign key of sorts, relating file metadata to its hash. I wrote this script to quickly extract out all hashes associated with a particular vendor. It craps out before it finishes processing hashes.csv stored_ids = [] # this file is about 1 MB entries = csv.reader(open(options.entries, "rb")) for row in entries: # row[2] is the vendor if row[2] == options.vendor: # row[0] is the ID stored_ids.append(row[0]) # this file is 1 GB hashes = open(options.hashes, "rb") # I iteratively read the file here, # just in case the csv module doesn't do this. for line in hashes: # not sure if stored_ids contains strings or ints here... # this probably isn't the problem though if line.split(",")[0] in stored_ids: # if its one of the IDs we're looking for, print the file and hash to STDOUT print "%s,%s" % (line.split(",")[2], line.split(",")[4]) hashes.close() This script gets about 2000 entries through hashes.csv before it halts. What am I doing wrong? I thought I was processing it line by line. ps. the csv files are the popular HashKeeper format and the files I am parsing are the NSRL hash sets. http://www.nsrl.nist.gov/Downloads.htm#converter UPDATE: working solution below. Thanks everyone who commented! entries = csv.reader(open(options.entries, "rb")) stored_ids = dict((row[0],1) for row in entries if row[2] == options.vendor) hashes = csv.reader(open(options.hashes, "rb")) matches = dict((row[2], row[4]) for row in hashes if row[0] in stored_ids) for k, v in matches.iteritems(): print "%s,%s" % (k, v)

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  • assign operator to variable in python?

    - by abhilashm86
    Usual method of applying mathematics to variables is a * b Is it able to calculate and manipulate two operands like this? a = input('enter a value') b = input('enter a value') op = raw_input('enter a operand') then how do i connect op and two variables a and b?? i know i can compare op to +, -, %, $ and then assign and compute.... but can i do something like a op b , how to tell compiler that op is an operator?? any tweaks possible?

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  • Python - Blackjack

    - by user335932
    def showCards(): #SUM sum = playerCards[0] + playerCards[1] #Print cards print "Player's Hand: " + str(playerCards) + " : " + "sum print "Dealer's Hand: " + str(compCards[0]) + " : " + "sum" compCards = [Deal(),Deal()] playerCards = [Deal(),Deal()] How can i add up the interger element of a list containing to values? under #SUM error is can combine lists like ints...

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  • Most efficient way to search the last x lines of a file in python

    - by Harley
    I have a file and I don't know how big it's going to be (it could be quite large, but the size will vary greatly). I want to search the last 10 lines or so to see if any of them match a string. I need to do this as quickly and efficiently as possible and was wondering if there's anything better than: s = "foo" last_bit = fileObj.readlines()[-10:] for line in last_bit: if line == s: print "FOUND"

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  • Importing files in Python from __init__.py

    - by Federico Builes
    Suppose I have the following structure: app/ __init__.py foo/ a.py b.py c.py __init__.py a.py, b.py and c.py share some common imports (logging, os, re, etc). Is it possible to import these three or four common modules from the __init__.py file so I don't have to import them in every one of the files? Edit: My goal is to avoid having to import 5-6 modules in each file and it's not related to performance reasons.

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  • Generate a table of contents from HTML with Python

    - by Oli
    I'm trying to generate a table of contents from a block of HTML (not a complete file - just content) based on its <h2> and <h3> tags. My plan so far was to: Extract a list of headers using beautifulsoup Use a regex on the content to place anchor links before/inside the header tags (so the user can click on the table of contents) -- There might be a method for replacing inside beautifulsoup? Output a nested list of links to the headers in a predefined spot. It sounds easy when I say it like that, but it's proving to be a bit of a pain in the rear. Is there something out there that does all this for me in one go so I don't waste the next couple of hours reinventing the wheel? A example: <p>This is an introduction</p> <h2>This is a sub-header</h2> <p>...</p> <h3>This is a sub-sub-header</h3> <p>...</p> <h2>This is a sub-header</h2> <p>...</p>

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  • Can't parse XML effectively using Python

    - by Harshit Sharma
    import urllib import xml.etree.ElementTree as ET def getWeather(city): #create google weather api url url = "http://www.google.com/ig/api?weather=" + urllib.quote(city) try: # open google weather api url f = urllib.urlopen(url) except: # if there was an error opening the url, return return "Error opening url" # read contents to a string s = f.read() tree=ET.parse(s) current= tree.find("current_condition/condition") condition_data = current.get("data") weather = condition_data if weather == "<?xml version=": return "Invalid city" #return the weather condition #return weather def main(): while True: city = raw_input("Give me a city: ") weather = getWeather(city) print(weather) if __name__ == "__main__": main() gives error , I actually wanted to find values from google weather xml site tags

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