CODEWITHSUNDEEP
pythonif-statementconditional-statements
user15649753
user15649753

Reputation:

Figure out which part of or statement matches condition?

I have a fundamental and basic python question. I searched in the google but I couldn't find the answer. I am wondering when I use or in if condition is there any way to see which part of if condition is correct in the following example.

I have list : my= ['A','B','C']

if 'S' in my or 'T' in my or 'C' in my:
    print('yes')     # now I wanna know which one is correct. the answer here is `C`

Note : I know I can use for loop over elements of my to figure it out. I am wondering if there is a keycode for that or not.

Upvotes: 2

Views: 179

Answers (4)

no comment
no comment

Reputation: 10152

Repetitive walrus one:

if (x := 'S') in my or (x := 'T') in my or (x := 'C') in my:
    print('yes', x)

With your list it prints yes C.

I see chepner already posted a similar one. Mine has more code repetition, but has the advantage of being lazy, evaluating only as many expressions as needed, until the first hit.

Try it online!

Upvotes: 1

Ofer Sadan
Ofer Sadan

Reputation: 11922

Since both repeated code and any are already in other answers, I thought it would be worthwhile to give another angle as an example of a one-liner if:

print('S' if 'S' in my else 'T' if 'T' in my else 'C' if 'C' in my else 'Nothing')

Or if you're ok with loops, a one-liner can look like this:

print([char for char in 'STC' if char in my][0])  # Would throw IndexError if not found

Upvotes: 0

chepner
chepner

Reputation: 530940

Consider the following use of any. It would be nice if you could write

# NameError on print(x)
if any(x in my for x in ['S', 'T', 'C']):
    print(x)

except x is only in scope for the generator expression. You can, however, use an assignment expression to capture the last assignment to x for use after any returns.

if any((witness := x) in my for x in ['S', 'T', 'C']):
    print(witness)

witness is repeatedly set to x; when a comparison finally succeeds, any stops making comparisons, so witness is left set to the last value checked.

Upvotes: 2

quamrana
quamrana

Reputation: 39354

You have to isolate each expression so you can test it later:

my = ['A','B','C']

S = 'S' in my
T = 'T' in my
C = 'C' in my
if S or T or C:
    # Now examine S, T and C separately
    print('yes')

Upvotes: 0

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