Assign variable names to different files in python

Question

I am trying to open various text files simulataneously in python. I want to assign a unique name to each file. I have tried the follwoing but it is not working:

for a in [1,2,11]:
    "DOS%s"%a=open("DOS%s"%a,"r")

Instead I get this error:

SyntaxError: can't assign to operator

What is the correct way to do this?

You're misusing the word simultaneously

Tim
– Tim

2014-05-15 12:25:24 +00:00
Commented May 15, 2014 at 12:25 — Tim
– Tim, Commented May 15, 2014 at 12:25

galinden · Accepted Answer · 2014-05-15 12:35:51Z

3

you always have to have the namespace declared before assignment, either on a previous line or on the left of a statement. Anyway you can do:

files = {f:open("DOS%s" % f) for f in [1,2,11]}

then access files like:

files[1].read()

answered May 15, 2014 at 12:35

galinden

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Comments

OneOfOne · Accepted Answer · 2014-05-15 12:26:26Z

2

Use a dict :

files = {}
for a in [1,2,11]:
    files["DOS%s"%a] = open("DOS%s"%a,"r")

answered May 15, 2014 at 12:26

OneOfOne

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Comments

Henrik · Accepted Answer · 2014-05-15 12:34:37Z

0

You get an error because you're trying to assign a value to something that is not a variable. This is pretty basic stuff, so I'd suggest that you do some sort of introductory programming course.

When you need a string as a lookup key, a dictionary is your friend:

files = {}
for a in [1, 2, 11]:
    filename = 'DOS%s' % a
    files[filename] = open(filename, 'r')

edited May 15, 2014 at 12:34

answered May 15, 2014 at 12:27

Henrik

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4 Comments

comiventor Over a year ago

a shorter way dosfiles = {"DOS%s"%a: open("DOS%s"%a,"r") for a in [1,2,11]}

Henrik Over a year ago

@comiventor A lot less readable in my opinion. Newlines are not your enemy :)

comiventor Over a year ago

surely not @Henrik :) I wanted to break the dictionary comprehension into two lines but pressing enter in comment just posts it instead of newline.

Henrik Over a year ago

Come to think of it, it's not a bad idea to do this in a comprehension, but the double formatting string bugs me.

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