CODEWITHSUNDEEP
pythonstring
رضا پریور
رضا پریور

Reputation: 698

How to check if a string starts with a tuple of substring and get the matched one?

I know how to check if a string starts with some substring like this:

text.startswith(("one", "two", "three", "four"))

but how to get which one is matched?

Upvotes: 3

Views: 1070

Answers (5)

Jean-François Fabre
Jean-François Fabre

Reputation: 140256

Use a comprehension and next:

>>> text = "two dogs"
>>> lst = ("one", "two", "three", "four")
>>> next((item for item in lst if text.startswith(item)),None)
'two'

item for item in lst if text.startswith(item) yields item if condition is True. next iterates manually on the expression at most once.

If no string matches, the expression returns None. First match ends the search.

Upvotes: 1

7koFnMiP
7koFnMiP

Reputation: 477

You could loop over the elements in the tuple:

mytuple = ("one", "two", "three", "four")
text = "one dog"
for i in mytuple:
    if text.startswith(i):
        print(i)
        break
>>> one

Upvotes: 4

Tomerikoo
Tomerikoo

Reputation: 19422

You can use regex by building a pattern from the tuple and then extract the match:

import re

subs = ("one", "two", "three", "four")
text = "three and a half"

if r := re.match("|".join(subs), text):
    print(r.group())
else:
    print("No match found")

Using re.match, this provides the same functionality as str.startswith.

For versions older than Python 3.8, use explicit assignment:

r = re.match("|".join(subs), text)
if r:
    print(r.group())

Upvotes: 4

Ali Sajjad Rizavi
Ali Sajjad Rizavi

Reputation: 4490

One line version. This will give the list of all words which appear in the start of text.

startMatches = [word for word in ("one","two","three","four") if word == text[:len(word)]]

Upvotes: 0

JoshuaBox
JoshuaBox

Reputation: 775

Also a oneliner with list comprehension:

text = 'three-dimensional'
match_idxs = [i for i, substr in enumerate(("one", "two", "three", "four")) if text.startswith(substr)]
print('matching indexes: ', match_idxs)

>>> "matching indexes: [2]"

Upvotes: 0

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