Python – Maximum occurring Substring from list

Sometimes, while working with Python strings, we can have a problem in which we need to check for maximum occurring subtring from strings list. This can have application in DNA sequencing in Biology and other application. Lets discuss certain way in which this task can be performed.

Method : Using regex() + groupby() + max() + lambda
The combination of above functionalities can be used to solve this particular problem. In this, we first extract the sequences using regex function. Then the counter grouping is performed using groupby(). The last step is extracting maximum which is done using max() along with lambda function.





# Python3 code to demonstrate working of 
# Maximum occurring Substring from list
# Using regex() + groupby() + max() + lambda
import re 
import itertools
# initializing string
test_str = "gfghsisbjknlmkesbestgfgsdcngfgcsdjnisdjnlbestdjsklgfgcdsbestbnjdsgfgdbhisbhsbestdkgfgb"
test_list = ['gfg', 'is', 'best']
# printing original string and list
print("The original string is : " + test_str)
print("The original list is : " + str(test_list))
# Maximum occurring Substring from list
# Using regex() + groupby() + max() + lambda
seqs = re.findall(str.join('|', test_list), test_str)
grps = [(key, len(list(j))) for key, j in itertools.groupby(seqs)]
res = max(grps, key = lambda ele : ele[1])
# printing result 
print("Maximum frequency substring : " + str(res[0])) 


Output :

The original string is : gfghsisbjknlmkesbestgfgsdcngfgcsdjnisdjnlbestdjsklgfgcdsbestbnjdsgfgdbhisbhsbestdkgfgb
The original list is : ['gfg', 'is', 'best']
Maximum frequency substring : gfg
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