I'm trying to generate a series of (empty) lists using a for loop in python, and I want the name of the list to include a variable. e.g. y0, y1, y2 etc. Ideally looking something like this:
for a in range (0,16777216):
global y(a)=[]
4 Answers
why wouldn't you do a dictionary of lists?
y = {}
for a in range (0,16777216):
y[a] = []
also for brevity: https://stackoverflow.com/a/1747827/884453
y = {a : [] for a in range(0,16777216)}
answered Aug 30, 2012 at 18:59
Francis Yaconiello
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3 Comments
kojiro
Except all the keys are integers, so perhaps a list of lists or sparse array?
Francis Yaconiello
i typo'd that a, it wasn't supposed to be a string. fixed.
Francis Yaconiello
added dict comprehension
Not sure if this is quite what you want but couldn't you emulate the same behavior by simply creating a list of lists? So your_list[0] would correspond to y0.
Comments
The answer is: don't. Instead create a list so that you access the variables with y[0], y[1], etc. See the accepted answer here for info.
1 Comment
Burhan Khalid
You should mark this question as a duplicate to the one you linked.
Maybe you should check out defaultdict
form collection import defaultdict
# This will lazily create lists on demand
y = defaultdict(list)
Also if you want a constraint on the key override the default __getitem__ function like the following...
def __getitem__(self, item):
if isintance(item, int) and 0 < item < 16777216:
return defaultdict.__getitem__(self, item)
else:
raise KeyError
dictor a list of lists, then that is your table-- no fakery required. In fact, the local variables you want to create would simply live in their ownlocals()dictionary. So under the hood you'd be using the same data structure, just far less conveniently, which doesn't make much sense.