Python incrementally set a variable to equal another variable

Question

I am attempting to set the value of a variable to incrementally equal that of another variable based on the iteration of the loop I am on.

I have the following code:

no_keywords=3

cat_0='Alpha'
cat_1='Bravo'
cat_2='Charlie'
cat_3='Delta'

for _ in range(no_keywords):

  keyword1 = exec(f'cat_{_}')
  
  print(keyword1)

However the printed value just returns a NoneType object. I would like the value of Keyword1 to take on the value of the cat_ variable based on the iteration of loop I am on.

Please can somebody help in explaining in what I am doing wrong and help me recitfy?

Thanks,

D

@Barmar "Don't do that. Use a list" and "Use eval(), not exec()" seem like contradictory pieces of advice. — khelwood, Feb 26 '21 at 23:16
@khelwood The first is a recommendation, the second is how to fix his code. — Barmar, Feb 26 '21 at 23:22
@Barmar And if they actually said that, they would not be contradictory. — khelwood, Feb 26 '21 at 23:26

score 1 · Accepted Answer · answered Feb 26 '21 at 22:59

1

Try this:

no_keywords = 3

cat_0 = 'Alpha'
cat_1 = 'Bravo'
cat_2 = 'Charlie'
cat_3 = 'Delta'

for _ in range(no_keywords):
    keyword1 = None

    exec(f'keyword1 = cat_{_}')

    print(keyword1)

Seems like exec does not return a value, but you can set your variable within the command passed to it.

answered Feb 26 '21 at 22:59

Rikki

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Thank you! That works perfectly :) – Drij Vyas Feb 26 '21 at 23:02
2

You can also use `eval()` to return the value of an expression. – Barmar Feb 26 '21 at 23:23

Python incrementally set a variable to equal another variable

1 Answers1