python 3 variable used in another variable's name?

Question

in python 3 (with tkinter) i have the following images:

SqImg1 = PhotoImage(file='SqImg1.gif')
SqImg2 = PhotoImage(file='SqImg2.gif')
SqImg3 = PhotoImage(file='SqImg3.gif')
SqImg4 = PhotoImage(file='SqImg4.gif')
...

i also have a function that needs to return one of those images based on a variable. so if the function determines var to be 1, it needs to return SqImg1...

def returnImage():
    list = ['ale', 'boo', 'boo', 'cat', 'doe', 'boo', 'eel']
    var = 0
    for item in list:
        if item == 'boo':
            var += 1
    return SqImg[var]

i would want the above to return SqImg3

this is probably simple, but i can't seem to find what im looking for with google.

Duncan · Accepted Answer · 2011-03-25 19:28:49Z

2

There's your mistake straight away:

SqImg1 = PhotoImage(file='SqImg1.gif')
SqImg2 = PhotoImage(file='SqImg2.gif')
SqImg3 = PhotoImage(file='SqImg3.gif')
SqImg4 = PhotoImage(file='SqImg4.gif')
...

should be:

SqImg = [
PhotoImage(file='SqImg1.gif'),
PhotoImage(file='SqImg2.gif'),
PhotoImage(file='SqImg3.gif'),
PhotoImage(file='SqImg4.gif'),
...
]

or even:

SqImg = [ PhotoImage(file='SqImg{}.gif'.format(i) for i in range(1, n) ]

answered Mar 25, 2011 at 19:28

Duncan

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3 Comments

Thomas Kirkpatrick Over a year ago

to save space? memory? whats the advantage (other than it looks much better)?

Greg Hewgill Over a year ago

@Thomas Kirkpatrick: to avoid repetition. Repeating yourself in code is often a sign that things could be done better.

Daenyth Over a year ago

@Thomas: Looking better is also a benefit. In this case though it's going to give you cleaner code.

dfb · Accepted Answer · 2011-03-25 19:22:51Z

0

Two options

Create a dictionary and map the strings to the actual variables. E.g., d = {}; d["boo"] = img3
Call eval() if your images are numbered correctly.. e.g., return eval("sqlimg%d" % var)

The first option is probably what you're looking for unless you have special circumstances

answered Mar 25, 2011 at 19:22

dfb

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1 Comment

Thomas Kirkpatrick Over a year ago

dictionary! should have known that. works great, just construct a string and look it up. 'SqImg3':SqImg3

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