finding an insertion in a string

A very underappreciated gem in the standard lib is difflib...

>>>
import difflib
   >>>
   s = difflib.SequenceMatcher(None, "GHSKWITNIFSI", "GHSKWAGDITNIFSI") >>>
   s.get_matching_blocks()[: -1]
   [(0, 0, 5), (5, 8, 7)] >>>
   s = difflib.SequenceMatcher(None, "GHSKWITNIFSI", "GHSKWITNIFSI") >>>
   s.get_matching_blocks()[: -1]
   [(0, 0, 12)]

This ... feels kludgy to a degree, and it's only probably half-way there, but it seems like it found the substring in your example and could probably be expanded a bit. I can revise it some in a minute with some more time to test, but it's an approach concept:

s1 = 'GHSKWITNIFSI'
s2 = 'GHSKWAGDITNIFSI'

l = len(s2) - len(s1)

for i in range(len(s1)):
   if s2[0: i] + s2[i + l: ] == s1:
   print i
break

def GetInsertedString(StringA, StringB):
   lenA = len(StringA)
lenB = len(StringB)
if lenA > lenB:
   return None, None
begincount = 0
while begincount < lenA and StringA[begincount] == StringB[begincount]:
   begincount += 1
endcount = 0
while endcount < (lenA - begincount) and StringA[lenA - endcount - 1] == StringB[lenB - endcount - 1]:
   endcount += 1
if begincount + endcount != lenA:
   return None, None
return begincount, StringB[begincount: begincount + lenB - lenA]

   >>>
   GetInsertedString('GHSKWITNIFSI', 'GHSKWAGDITNIFSI')
   (5, 'AGD') >>>
   GetInsertedString('GHSKWITNIFSI', 'GHSKWAGDTNIFSI')
   (None, None)

1._

from itertools
import dropwhile

def get_inserted_substring(s1, s2):
   try:
   # diff is the first index at which the strings differ
diff = dropwhile(lambda i: s1[i] == s2[i], xrange(len(s2))).next()
if s2[diff: ].endswith(s1[diff: ]):
   return (diff, s2[diff: diff - len(s1)])
except(StopIteration, IndexError):
   # the strings are the same or only differ at the end
if len(s1) <= len(s2):
   return (len(s1), s2[len(s1): ])
return (None, None)

And examples...

>>> get_inserted_substring('abcdef', 'abcXYZdef')
   (3, 'XYZ') >>>
   get_inserted_substring('abcdef', 'abRSTcdXYZef')
   (None, None) >>>
   get_inserted_substring('abcdef', 'abcdefXYZ')
   (6, 'XYZ') >>>
   get_inserted_substring('abcdef', 'XYZabcdef')
   (0, 'XYZ') >>>
   get_inserted_substring('abcdefXYZ', 'abcdef')
   (None, None)

strA = 'foor'
strB = 'foobar'
strC = 'ba'

if strB.replace(strC, '') == strA:
   print strC, ' at index ', len(strB.split(strC)[0])

Suggestion : 2

Last Updated : 17 Jul, 2022

Example 1:

Input:
   str1 = "heap", str2 = "pea"
Output:
   Minimum Deletion = 2 and
Minimum Insertion = 1
Explanation:
   p and h deleted from heap
Then, p is inserted at the beginning
One thing to note, though p was required yet
it was removed / deleted first from its position and
then it is inserted to some other position.
Thus, p contributes one to the deletion_count
and one to the insertion_count.

Example 2:

Input:
   str1 = "geeksforgeeks", str2 = "geeks"
Output:
   Minimum Deletion = 8
Minimum Insertion = 0

Minimum number of deletions = 2
Minimum number of insertions = 1

Minimum number of deletions = 2
Minimum number of insertions = 1

Suggestion : 3

non-member overloads: getline (string) operator+ (string) operator<< (string) operator>> (string) relational operators (string) swap (string) ,Other: <algorithm> <bitset> <chrono> <codecvt> <complex> <exception> <functional> <initializer_list> <iterator> <limits> <locale> <memory> <new> <numeric> <random> <ratio> <regex> <stdexcept> <string> <system_error> <tuple> <typeindex> <typeinfo> <type_traits> <utility> <valarray> ,functions: stod stof stoi stol stold stoll stoul stoull to_string to_wstring ,classes: string u16string u32string wstring

 string & insert(size_t pos,
    const string & str);

 string & insert(size_t pos,
    const string & str, size_t subpos, size_t sublen);

 string & insert(size_t pos,
    const char * s);

 string & insert(size_t pos,
    const char * s, size_t n);

 string & insert(size_t pos, size_t n, char c);
 void insert(iterator p, size_t n, char c);

iterator insert(iterator p, char c);

Suggestion : 4

What's the best way of checking if StringA = StringB with an another StringC inserted at some arbitrary point? , 1 week ago Feb 07, 2019 · size_t find (const string& str, size_t pos = 0); size_t find (const char* s, size_t pos = 0); Function parameters: str : The sub-string to be searched. s : The sub-string to be searched, given as C style string. pos : The initial position from where the string search is to begin. Function Return: , 5 days ago What we can do regarding the string insertion is to create a new string with the desired changes, like splitting the original string and inserting a new string in it. Insert String Into a String in Python Using the string.find() Method. We first use the string.find() method to get the substring index in the string, after which we need to insert ... , 4 days ago Oct 27, 2014 · CHARINDEX can start at a certain position in the string while PATINDEX can take wildcards. In this simplistic case, we can use either one. I …

>>>
import difflib >>> s = difflib.SequenceMatcher(None, "GHSKWITNIFSI", "GHSKWAGDITNIFSI") >>> s.get_matching_blocks()[: -1][(0, 0, 5), (5, 8, 7)] >>> s = difflib.SequenceMatcher(None, "GHSKWITNIFSI", "GHSKWITNIFSI") >>> s.get_matching_blocks()[: -1][(0, 0, 12)]

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