Python list comprehension with multiple conditions

Question

I have a list of strings

str_list = ['a', 'b', 'c']

and want to add a suffix

suffix = '_ok'

when the string value is 'a'.

This works:

new_str_list = []
for i in str_list:
    if i == 'a':
        new_str_list.append(i + suffix)
    else:
        new_str_list.append(i)

new_str_list
# ['a_ok', 'b', 'c']

How can I simplify this with a list comprehension? Something like

new_str_list = [i + suffix for i in str_list if i=='a' ....

`[i + suffix for i in str_list if i == 'a' else i]` – Ghost Ops Oct 21 '21 at 09:53 — Ghost Ops, Oct 21 '21 at 09:53
@GhostOps gives SyntaxError: invalid syntax – makpalan Oct 21 '21 at 09:54 — makpalan, Oct 21 '21 at 09:54
@GhostOps That ain't no Python :) – user2390182 Oct 21 '21 at 09:59 — user2390182, Oct 21 '21 at 09:59

score 4 · Accepted Answer · answered Oct 21 '21 at 09:54

4

[i + suffix if i == 'a' else i for i in str_list]

Putting if after the for as you tried is for skiping values.

In your case you don't skip values but process them differently.

answered Oct 21 '21 at 09:54

log0

10,210
3
24
61

score 2 · Answer 2 · answered Oct 21 '21 at 09:54

2

Create the item according to it's value -

[i + suffix if i=='a' else i for i in str_list ]

answered Oct 21 '21 at 09:54

Tom Ron

5,322
2
16
32

score 2 · Answer 3 · answered Oct 21 '21 at 09:56

2

A concise option making use of fact that False == 0:

[i + suffix * (i=='a') for i in str_list]

answered Oct 21 '21 at 09:56

user2390182

67,685
6
55
77

Python list comprehension with multiple conditions

3 Answers3