setting variables in a for loop python

Question

I have this code

for i in range(10):
    variablename = "file" + str(i)

and I want to be able to go generate variables depending on the i variable like if range was to 10 would have variables like this

file1
file2
file3
file4
file5
file6
file7
file8
file9
file10

How would I do this?

just use a `list` and `append`, [look here](http://docs.python.org/2/tutorial/datastructures.html) — Claudiordgz, Mar 26 '14 at 18:46
okay so I don't know how to use a dictionary and Ruben bermudez I want it to work wnatever the range is so if its 10 then it does ten variables but if its 20 it does 20 a so on so fourth — Marley Plant, Mar 26 '14 at 18:48

score 4 · Accepted Answer · answered Mar 26 '14 at 18:50

4

You can use a Dictionary

dict = {}
for i in range(10):
    dict["file" + str(i)] = "value for this var"

then you can obtain a value using the variable name

f1 = dict["file1"]

answered Mar 26 '14 at 18:50

Andres Felipe Ruiz

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score 1 · Answer 2 · edited May 23 '17 at 12:02

1

you could use globals() function which contains a dictionary of all the global variables. To which I recommend reading these two pages if you are unfamiliar with scope, or dictionaries

http://docs.python.org/2/library/stdtypes.html#typesmapping

Short Description of the Scoping Rules?

for i in range(10):
    globals()["file" + str(i)] = "newvarvalue!" + str(i)
print file0
print file1
print file2
print file3
print file4
print file5
print file6
print file7
print file8
print file9

EDIT removed locals() from solution

edited May 23 '17 at 12:02

Community

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1

answered Mar 26 '14 at 18:51

flakes

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generally speaking this is a bad idea ... I think – Joran Beasley Mar 26 '14 at 18:51
@Joran Beasley much agreed. – flakes Mar 26 '14 at 18:55
@Joran Beasley however, it does directly answers op's question – flakes Mar 26 '14 at 18:56

score 0 · Answer 3 · edited May 23 '17 at 10:30

0

list comprehensions

filenames = ["file%d.txt"%i for i in range(1,11)]

or if you want them as variable names store them in a dictionary as suggested in P0lyb1us's Answer

edited May 23 '17 at 10:30

Community

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answered Mar 26 '14 at 18:50

Joran Beasley

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cheese12345 · Answer 4 · 2014-07-10T19:32:14.137

-4

You you need to give range() two arguments for it to work so you should change your code to:

for i in range(1,11):
     variablename = "file" + str(i)

edited Jul 10 '14 at 19:32

answered Mar 26 '14 at 18:46

cheese12345

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No. He merely needs to change `range(10)` into something like `range(1,11)` instead. – WGS Mar 26 '14 at 18:49
2

I don't think the question is "why am I getting file0 instead of file1 as my first element?" but rather, "how do I take this string, and make it be the name of a variable?" – Kevin Mar 26 '14 at 18:50
This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient [reputation](http://stackoverflow.com/help/whats-reputation) you will be able to [comment on any post](http://stackoverflow.com/help/privileges/comment). – Ansgar Wiechers Mar 26 '14 at 19:28

setting variables in a for loop python

4 Answers4