How to compare two strings as file content in python?-CodePudding

I have a file at a certain location, which was generated by python code. I want to run the same code, to generate another file, but with the same name and the same location, so it will replace the first one. Before running the code, I saved the initial file contents to a string. After running the code, I saved the final file contents to another string. How could I compare data_initial and data_final strings as file contents and to highlight exactly what words differ in those two strings? I tried like this:

    data_initial="1234"
    data_final="12345 new thing"
    first_set = set(data_initial)
    second_set = set(data_final)
    difference = first_set.symmetric_difference(second_set)

But this gives me:

difference is
 {'t', 'n', ' ', 'i', '5', 'e', 'h', 'w', 'g'}

I would like to see the words which are different, like

12345 new thing

Also if it's possible to check for each phrase that changed.

CodePudding user response：

you are using set also remember that string in python is a list even a single character. the symmetric_difference return a list of new character.

https://stackoverflow.com/a/30683765/18846844 this may satisfy what you want:

I changed the solution by using a single loop. How about this:

# First, I removed the split... it is already an array
str1 = input("Enter first string:")
str2 = input("Enter second string:")

#then creating a new variable to store the result after  
#comparing the strings. You note that I added result2 because 
#if string 2 is longer than string 1 then you have extra characters 
#in result 2, if string 1 is  longer then the result you want to take 
#a look at is result 2

result1 = ''
result2 = ''

#handle the case where one string is longer than the other
maxlen=len(str2) if len(str1)<len(str2) else len(str1)

#loop through the characters
for i in range(maxlen):
  #use a slice rather than index in case one string longer than other
  letter1=str1[i:i 1]
  letter2=str2[i:i 1]
  #create string with differences
  if letter1 != letter2:
    result1 =letter1
    result2 =letter2

#print out result
print ("Letters different in string 1:",result1)
print ("Letters different in string 2:",result2)

CodePudding user response：

If you want to get the changed words, not chars, simply transform your whole strings in lists and then sets of words by calling split() - see code below. Also, the same can be done if you want to get which sentences are changed in a paragraph, probably splitting by \n or .

str1 = "the quick brown fox jumps over the lazy dog"
str2 = "the slow brown bull jumps over the crazy frog"
wset1=set(list(str1))
wset2=set(list(str2))

##words that are in one sentence and not in the other
wset1.symmetric_difference(wset2)
{'slow', 'crazy', 'frog', 'fox', 'quick', 'bull', 'lazy', 'dog'}

##words in str1 and not in str2
wset1.difference(wset2)
{'fox', 'quick', 'lazy', 'dog'}

But if you want a more comprehensive solution, i.e. you want to know which words replaced which, you should have a look at the standard library difflib module.