Shorten an if statement whose statement are reversed

Question

I have the following situation:

string = "abc"
if (string[1] == "b" and string[2] == "c") or (string[1] == "c" and string[2] == "b"):
    print("ERROR")

Is there a solution to shorten this in a pythonic way? I see that (string[1] == "b" and string[2] == "c") is the reverse statement of (string[1] == "c" and string[2] == "b"). Maybe I can use that?

`string[1] == "b" and string[2] == "c"` isn't the reverse statement of `string[1] == "c" and string[2] == "b"`. This is `!(string[1] == "b" and string[2] == "c")` or `string[1] != "b" OR string[2] != "c"` — Cid, Oct 11 '19 at 12:53
Are the indices important, or do you actually want to check if the substr "bc" or "cb" exists inside `string` ? — Wololo, Oct 11 '19 at 12:54
@magnus I want to check if the substring "bc" or "cb" exists inside the string. But they have to be the second an third letter — Larsus, Oct 11 '19 at 12:58
@magnus I know, I'm telling OP that your question is relevant — Cid, Oct 11 '19 at 13:36

RomanPerekhrest · Accepted Answer · 2019-10-11T13:01:12.097

6

Is there a solution to shorten this in a pythonic way?

Yes, here it is:

string = "abc"
if (string[1:3] == "bc") or (string[1:3] == "cb"):
    print("ERROR")

If eagering for a more short way - if string[1:3] in ('bc', 'cb'):

edited Oct 11 '19 at 13:01

answered Oct 11 '19 at 12:53

RomanPerekhrest

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Might add that if the pattern is arbitrary and stored in a variable named, say `pattern="bc"`, it may be reversed by `pattern[::-1]` to obtain "cb" – Wololo Oct 11 '19 at 13:03

Shorten an if statement whose statement are reversed

1 Answers1