In Python it's possible to create a procedure that has no explicit return. i.e.: def test(val): if 0 == val: return 8 Further, it's possible to assign the results of that function to a variable: >>> a = test(7) >>> print `a` 'None' Why the heck is that? What language logic is behind that baffling design decision? Why ...
I have to make a rudimentary FSM in a class, and am writing it in Python. The assignment requires we read the transitions for the machine from a text file. So for example, a FSM with 3 states, each of which have 2 possible transitions, with possible inputs 'a' and 'b', wolud have a text file that looks like this: 2 # first li...
This is my first python program - Requirement: Read a file consisting of {adId UserId} in each line. For each adId, print the number of unique userIds. Here is my code, put together from reading the python docs. Could you give me feedback on how I can write this in more python-ish way? CODE : import csv adDict = {} reader = csv.rea...
Hello, my Python class has some variables that require work to calculate the first time they are called. Subsequent calls should just return the precomputed value. I don't want to waste time doing this work unless they are actually needed by the user. So is there a clean Pythonic way to implement this use case? My initial thought was ...
I'm using this simple function: def print_players(players): tot = 1 for p in players: print '%2d: %15s \t (%d|%d) \t was: %s' % (tot, p['nick'], p['x'], p['y'], p['oldnick']) tot += 1 and I'm supposing nicks are no longer than 15 characters. I'd like to keep each "column" aligned, is there a some syntactic suga...
I'd like to know the best way (more compact and "pythonic" way) to do a special treatment for the last element in a for loop. There is a piece of code that should be called only between elements, being suppressed in the last one. Here is how I currently do it: for i, data in enumerate(data_list): code_that_is_done_for_every_element ...
I'm importing from a CSV and getting data roughly in the format { 'Field1' : 3000, 'Field2' : 6000, 'RandomField' : 5000 } The names of the fields are dynamic. (Well, they're dynamic in that there might be more than Field1 and Field2, but I know Field1 and Field2 are always going to be there. I'd like to be able to pass in this dict...
I can't seem to find an elegant way to start from t and result in s. >>>t = ['a',2,'b',3,'c',4] #magic >>>print s {'a': 2, 'c': 4, 'b': 3} Solutions I've come up with that seems less than elegant : s = dict() for i in xrange(0, len(t),2): s[t[i]]=t[i+1] # or something fancy with slices that I haven't figured out yet It's obviously ...
I have a definition like this def bar(self, foo=None, bar=None, baz=None): pass I want to make sure a maximum of one of foo, bar, baz is passed. I can do if foo and bar: raise Ex() if foo and baz: raise Ex() .... But there got be something simpler. ...
All of these start from a simple idea: How to write python-style formatted string in ocaml. pythoners could init a string as: str = "this var: %s" % this_var str2 = "this: %s; that: %s" % (this_var, that_var) but ocaml's formatted string code as : let str = Printf.sprintf "this var: %s" this_var let str2 = Printf.sprintf "this: %s; ...
I have a sumranges() function, which sums all the ranges of consecutive numbers found in a tuple of tuples. To illustrate: def sumranges(nums): return sum([sum([1 for j in range(len(nums[i])) if nums[i][j] == 0 or nums[i][j - 1] + 1 != nums[i][j]]) for i in range(len(nums))])...
Count the longest sequence of heads and tails in 200 coin flips. I did this - is there a niftier way to do it in python? (without being too obfuscated) import random def toss(n): count = [0,0] longest = [0,0] for i in xrange(n): coinface = random.randrange(2) count[coinface] += 1 count[not coinface]...
So according to the Zen of Python ... Explicit is better than implicit...Sparse is better than dense...Readability counts...but then again Flat is better than nested...so then which is pythonic? val = "which is pythonic?" print("".join(reversed(val))) or print(val[::-1]) I'm just a Java programmer learning Python so I find this py...
Is there a more succinct/correct/pythonic way to do the following: url = "http://0.0.0.0:3000/authenticate/login" re_token = re.compile("<[^>]*authenticity_token[^>]*value=\"([^\"]*)") for line in urllib2.urlopen(url): if re_token.match(line): token = re_token.findall(line)[0] break I want to get the value of the i...
Hi all I have the following code. class person(object): def __init__(self, keys): for item in keys: setattr(self, item, None) def __str__(self): return str(self.__dict__) def __eq__(self, other) : return self.__dict__ == other.__dict__ Now I want to take this code and only do...
Is there a shorter (perhaps more pythonic) way of opening a text file and reading past the lines that start with a comment character? In other words, a neater way of doing this fin = open("data.txt") line = fin.readline() while line.startswith("#"): line = fin.readline() ...
I came across this (really) simple program a while ago. It just outputs the first x primes. I'm embarrassed to ask, is there any way to make it more "pythonic" ie condense it while making it (more) readable? Switching functions is fine; I'm only interested in readability. Thanks from math import sqrt def isprime(n): if n ==2: ...
In some part of my Python program I have a val variable that can be 1 or 0. If it's 1 I must change to 0, if it's 0 I must change to 1. How do you do it in a Pythonic way? if val == 1: val = 0 elif val == 0: val = 1 it's too long! I did: swap = {0: 1, 1:0} So I can use it: swap[val] Other ideas? ...
I have some variables and I want to select the first one that evaluates to True, or else return a default value. For instance I have a, b, and c. My existing code: result = a if a else (b if b else (c if c else default)) Another approach I was considering: result = ([v for v in (a, b, c) if v] + [default])[0] But they both feel me...
Hi all, I am pulling a variety of information sources to build up a profile of a person. Once I do this I want to the flexibility to look at a person in a different ways. I don't have a lot of expierience in django so I would like a critique (be gentle) of my model. Admittedly even as I coded this I'm thinking redundancy (against DRY...