Python | Formas de contar el número de substrings en una string

Dada una string y una substring, escriba un programa de Python para encontrar cuántos números de substrings hay en la string (incluidos los casos superpuestos). Analicemos algunos métodos a continuación.

Método #1: Usar el método re.findall()

# Python code to demonstrate
# to count total number
# of substring in string
 
import re
# Initialising string
ini_str = "ababababa"
sub_str = 'aba'
 
# Count count of substrings using re.findall
res = len(re.findall('(?= aba)', ini_str))
 
# Printing result
print("Number of substrings", res)

Método #2: Usar el método re.finditer()

# Python code to demonstrate
# to count total number
# of substring in string
 
import re
# Initialising string
ini_str = "ababababa"
sub_str = 'aba'
 
# Count count of substrings using re.finditer
res = sum(1 for _ in re.finditer('(?= aba)', ini_str))
 
# Printing result
print("Number of substrings", res)

  Método #3: Usar empieza con() 

# Python code to demonstrate
# to count total number
# of substring in string
 
# Initialising string
ini_str = "ababababa"
sub_str = 'aba'
 
# Count count of substrings using startswith
res = sum(1 for i in range(len(ini_str))
         if ini_str.startswith("aba", i))
 
# Printing result
print("Number of substrings", res)

Number of substrings 4

Método #4: Usar el método count()

# Python code to demonstrate
# to count total number
# of substring in string
 
# Initialising string
ini_str = "ababababa"
sub_str = 'aba'
# Count count of substrings using count
def Countofoccurrences(ini_str,sub_str):
 
    # Initialize count and start to 0
    count = 0
    start = 0
 
    # Search through the string till
    # we reach the end of it
    while start < len(ini_str):
 
        # Check if a substring is present from
        # 'start' position till the end
        pos = ini_str.find(sub_str, start)
 
        if pos != -1:
            # If a substring is present, move 'start' to
            # the next position from start of the substring
            start = pos + 1
 
            # Increment the count
            count += 1
        else:
            # If no further substring is present
            break
    # return the value of count
    return count
# Printing result
print("Number of substrings", Countofoccurrences(ini_str,sub_str))

Number of substrings 4