CODEWITHSUNDEEP
pythonstringloops
Chip
Chip

Reputation: 471

Python multiple substring index in string

Given the following list of sub-strings:

sub = ['ABC', 'VC', 'KI']

is there a way to get the index of these sub-string in the following string if they exist?

s = 'ABDDDABCTYYYYVCIIII'

so far I have tried:

for i in re.finditer('VC', s):
  print(i.start, i.end)

However, re.finditer does not take multiple arguments.

thanks

Upvotes: 0

Views: 282

Answers (6)

Hari
Hari

Reputation: 47

Just Use String index Method

list_ = ['ABC', 'VC', 'KI']

s = 'ABDDDABCTYYYYVCIIII'


for i in list_:
    if i in s:
        print(s.index(i))

Upvotes: 0

Adon Bilivit
Adon Bilivit

Reputation: 27120

A substring may occur more than once in the main string (although it doesn't in the sample data). One could use a generator based around a string's built-in find() function like this:

note the source string has been modified to demonstrate repetition

sub = ['ABC', 'VC', 'KI']
s = 'ABCDDABCTYYYYVCIIII'

def find(s, sub):
    for _sub in sub:
        offset = 0
        while (idx := s[offset:].find(_sub)) >= 0:
            yield _sub, idx + offset
            offset += idx + 1

for ss, start in find(s, sub):
    print(ss, start)

Output:

ABC 0
ABC 5
VC 13

Upvotes: 1

Gábor Fekete
Gábor Fekete

Reputation: 1358

Another approach with re, if there can be multiple indices then this might be better as the list of indices is saved for each key, when there is no index found, the substring won't be in the dict.

import re
s = 'ABDDDABCTYYYYVCIIII'
sub = ['ABC', 'VC', 'KI']

# precompile regex pattern
subpat = '|'.join(sub)
pat = re.compile(rf'({subpat})')

matches = dict()
for m in pat.finditer(s):
    # append starting index of found substring to value of matched substring
    matches.setdefault(m.group(0),[]).append(m.start()) 

print(f"{matches=}")
print(f"{'KI' in matches=}")
print(f"{matches['ABC']=}")

Outputs:

matches={'ABC': [5], 'VC': [13]}
'KI' in matches=False
matches['ABC']=[5]

Upvotes: 0

Triet Doan
Triet Doan

Reputation: 12085

How about using list comprehension with str.find?

s = 'ABDDDABCTYYYYVCIIII'
sub = ['ABC', 'VC', 'KI']
results = [s.find(pattern) for pattern in sub]

print(*results) # 5 13 -1

Upvotes: 0

bn_ln
bn_ln

Reputation: 1683

You could map over the find string method.

s = 'ABDDDABCTYYYYVCIIII'
sub = ['ABC', 'VC', 'KI']

print(*map(s.find, sub))
# Output 5 13 -1

Upvotes: 0

bereal
bereal

Reputation: 34292

You can join those patterns together using |:

import re
sub = ['ABC', 'VC', 'KI']
s = 'ABDDDABCTYYYYVCIIII'

r = '|'.join(re.escape(s) for s in sub)
for i in re.finditer(r, s):
    print(i.start(), i.end())

Upvotes: 2

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