Dada una string y una substring, la tarea de encontrar el índice inicial para todas las apariciones de una substring dada en una string. Analicemos algunos métodos para resolver la tarea dada.
Método n.º 1: uso del método ingenuo
# Python3 code to demonstrate
# to find all occurrences of substring in
# a string
# Initialising string
ini_string = 'xbzefdgstbzefzexezef'
# Initialising sub-string
sub_string = 'zef'
# Printing initial string and sub-string
print ("initial_strings : ", ini_string, "\nsubstring : ", sub_string)
res = []
flag = 0
k = 0
# Finding all occurrences of substring
# in a string using Naive method
for i in range(0, len(ini_string)):
k = i
flag = 0
for j in range(0, len(sub_string)):
if ini_string[k] != sub_string[j]:
flag = 1
if flag:
break
k = k + 1
if flag == 0:
res.append(i)
# printing result(
print ("resultant positions", str(res))
Producción:
initial_strings : xbzefdgstbzefzexezef substring : zef resultant positions [2, 10, 17]
&nsbp;
Método #2: Usar la comprensión de listas
# Python3 code to demonstrate
# to find all occurrences of substring in
# a string
# Initialising string
ini_string = 'xbzefdgstbzefzexezef'
# Initialising sub-string
sub_string = 'zef'
# Printing initial string and sub-string
print ("initial_strings : ", ini_string, "\nsubstring : ", sub_string)
res = []
# Finding all occurrences of substring
# in a string using list comprehension
res = [i for i in range(len(ini_string))
if ini_string.startswith(sub_string, i)]
# printing result(
print ("resultant positions", str(res))
Producción:
initial_strings : xbzefdgstbzefzexezef substring : zef resultant positions [2, 10, 17]
Método #3: Usar expresiones regulares
# Python3 code to demonstrate
# to find all occurrences of substring in
# a string
import re
# Initialising string
ini_string = 'xbzefdgstbzefzexezef'
# Initialising sub-string
sub_string = 'zef'
# Printing initial string and sub-string
print ("initial_strings : ", ini_string, "\nsubstring : ", sub_string)
res = []
# Finding all occurrences of substring
# in a string using re.finditer
res = [m.start() for m in re.finditer(sub_string, ini_string)]
# printing result(
print ("resultant positions", str(res))
Producción:
initial_strings : xbzefdgstbzefzexezef substring : zef resultant positions [2, 10, 17]
Publicación traducida automáticamente
Artículo escrito por garg_ak0109 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA