Python use in the same line "For", "If" and "Else"

December 16, 2022

I want to learn python "secrets", it’s possible to put all this code in one line?:

word_not_clean="Casà: 25$"
word_clean=""
for x in word_not_clean:
    if x in 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789':
        word_clean+=x
    else:
        word_clean+='_'

This sentences work, but no replace especial characters:

word_clean="".join(x for x in word_not_clean if x in 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789')

But this sentence with else doesn’t works.

word_clean="".join(x for x in word_not_clean if x in 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789' else '_')

Thank you in advance.

>Solution :

There are two different kinds of if statements in generator expressions. The first kind (which I’ll call an “inclusion if”) comes after the for statement, and indicates whether a given item from an iterator should be included in the resultant list. This is what you’re using in the first example.

The second kind (which I’ll call a “ternary if”) comes before the if statement, and used Python’s ternary operator __ if __ else __ to decide what should be outputted by the iterator. This is what you want for the second example, but you need to reorder your terms:

OKAY = “abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789”
word_clean = "".join(
    x if x in ok else '_'  # Ternary if
    for x in word_not_clean
)