Count number of occurrences of a given substring in a string

Question

How can I count the number of times a given substring is present within a string in Python?

For example:

>>> \'foo bar foo\'.numberOfOccurre         


        

Answer 1

If you want to find out the count of substring inside any string; please use below code. The code is easy to understand that's why i skipped the comments. :)

string=raw_input()
sub_string=raw_input()
start=0
answer=0
length=len(string)
index=string.find(sub_string,start,length)
while index<>-1:
    start=index+1
    answer=answer+1
    index=string.find(sub_string,start,length)
print answer

Answer 2

For a simple string with space delimitation, using Dict would be quite fast, please see the code as below

def getStringCount(mnstr:str, sbstr:str='')->int:
    """ Assumes two inputs string giving the string and 
        substring to look for number of occurances 
        Returns the number of occurances of a given string
    """
    x = dict()
    x[sbstr] = 0
    sbstr = sbstr.strip()
    for st in mnstr.split(' '):
        if st not in [sbstr]:
            continue
        try:
            x[st]+=1
        except KeyError:
            x[st] = 1
    return x[sbstr]

s = 'foo bar foo test one two three foo bar'
getStringCount(s,'foo')

Answer 3

#counting occurence of a substring in another string (overlapping/non overlapping)
s = input('enter the main string: ')# e.g. 'bobazcbobobegbobobgbobobhaklpbobawanbobobobob'
p=input('enter the substring: ')# e.g. 'bob'

counter=0
c=0

for i in range(len(s)-len(p)+1):
    for j in range(len(p)):
        if s[i+j]==p[j]:
            if c<len(p):
                c=c+1
                if c==len(p):
                    counter+=1
                    c=0
                    break
                continue
        else:
            break
print('number of occurences of the substring in the main string is: ',counter)

Answer 4

string.count(substring), like in:

>>> "abcdabcva".count("ab")
2

Update:

As pointed up in the comments, this is the way to do it for non overlapping occurrences. If you need to count overlapping occurrences, you'd better check the answers at: "Python regex find all overlapping matches?", or just check my other answer below.

Answer 5

This makes a list of all the occurrences (also overlapping) in the string and counts them

def num_occ(str1, str2):
    l1, l2 = len(str1), len(str2)
    return len([str1[i:i + l2] for i in range(l1 - l2 + 1) if str1[i:i + l2] == str2])

Example:

str1 ='abcabcd'
str2 = 'bc'

will create this list but save only the BOLD values:

[ab, bc, ca, ab, bc, cd]

that will return:

len([bc, bc])

Answer 6

For overlapping count we can use use:

def count_substring(string, sub_string):
    count=0
    beg=0
    while(string.find(sub_string,beg)!=-1) :
        count=count+1
        beg=string.find(sub_string,beg)
        beg=beg+1
    return count

For non-overlapping case we can use count() function:

string.count(sub_string)