loop through array names using for loop python

Question

I have 3 arrays that is already defined:

array1[:,:,:]
array2[:,:,:]
array3[:,:,:]

In Unix I would do the following:

for ((i=1;i<4;i++))
do 
a = array$i[:,:,:]*1000
echo a 
done

This would give:

array1[:,:,:]
array2[:,:,:]
array3[:,:,:]

How can I do this in Python in a for loop?

Paritosh Singh · Accepted Answer · 2018-12-22 18:16:32Z

3

the completely legit nice way? put the 3 arrays in a list and iterate through that list.

a1 = [1, 2, 3]
a2 = [4, 5]
a3 = [6]

array_list = [a1, a2, a3]

for a in array_list:
    print(a)

Output:

[1, 2, 3]
[4, 5]
[6]

That is the ideal way to do it, you should not ideally be fiddling with names. However, is it possible if you want to using globals.

a1 = [1, 2, 3]
a2 = [4, 5]
a3 = [6]

for i in range(1, 4): #range is right exclusive
    print(globals()['a' + str(i)])

Output:

[1, 2, 3]
[4, 5]
[6]

However, just because it is possible does not mean it is recommended.

answered Dec 22, 2018 at 18:16

Paritosh Singh

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1 Comment

Thanks.. it helped :)

Nick Chapman · Accepted Answer · 2018-12-22 18:14:17Z

0

To do this in python it makes more sense to use a dict like so (and I'm ignoring that [:,:,:] is a syntax error):

arrays = {}
arrays[1] = [:,:,:]
arrays[2] = [:,:,:]
arrays[3] = [:,:,:]

for i in arrays:
    a = arrays[i] * 1000
    print(a)

answered Dec 22, 2018 at 18:14

Nick Chapman

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array1[:,:,:] is a valid syntax for numpy arrays.