Can the Python .replace() function replace whole phrases?

Question

I'm a video editor trying to automate word docs of talent scripts into STR files for captions to speed up the process. Since each video is structured the same, the idea works pretty well. In the scripts, there are editing directions that I'm trying to remove from the STR file I'm creating with Python and the python-docx library by using the .replace() function, however this doesn't seem to be working. These all begin with '(CUT' and the following possible sentences vary. The program correctly picks up where these sentences are occurring but the replace function yields no resulting change. What am I doing wrong here?

for x in range(2,len(doc.paragraphs)):
newPara = doc.paragraphs[x].text

if (newPara.find('(CUT') != -1):
    newPara.replace('(CUT', '')
   
    if (newPara.find('COMPLETE)') != -1):
        newPara.replace(' AWAY COMPLETE)', '')
       
    elif (newPara.find('TITLE)') != -1):
        newPara.replace(' AWAY TO TITLE)', '')

    elif (newPara.find('SIDE)') != -1):
        newPara.replace(' BACK TO SIDE)', '')

Strings are immutable objects, so `.replace` does not change the string in-place, but rather returns a new, changed string. You need to assign it back to the variable: `newPara = newPara.replace('(CUT', '')` — Błotosmętek, Feb 19 '20 at 21:08
your code indentation would throw an error as written. can you edit your code sample to to the correct indentation? e.g. tab before newPara — Tyler, Feb 19 '20 at 21:10
FWIW, you can do `if '(CUT' in newPara` instead of using `.find()`. That being said, you can also just do `newPara.replace('some string', '')` which just returns the original string if "some string" wasn't found. — b_c, Feb 19 '20 at 21:12
Welcome to Stack Overflow! Check out the [tour] and [ask] if you want advice. — wjandrea, Feb 19 '20 at 21:12

score 1 · Accepted Answer · answered Feb 19 '20 at 21:10

str.replace() doesn't mutate the original string - it returns the mutated string. you should re-assign to you variable:

#...
if (newPara.find('(CUT') != -1):
    newPara = newPara.replace('(CUT', '')

    if (newPara.find('COMPLETE)') != -1):
        newPara = newPara.replace(' AWAY COMPLETE)', '')

    elif (newPara.find('TITLE)') != -1):
        newPara = newPara.replace(' AWAY TO TITLE)', '')

    elif (newPara.find('SIDE)') != -1):
        newPara = newPara.replace(' BACK TO SIDE)', '')

John · Answer 2 · 2020-02-19T21:33:34.900

As the guy above said, strings are immutable and the str.replace() function returns a new string.

But adding to your code.

You don't need all those conditionals, the if the str.replace() does not find the substring you're looking for it returns the same string.

Example:

newPara = '(CUT AWAY COMPLETE) AWAY TO TITLE) BACK TO SIDE)Empty String'

if (newPara.find('(CUT') != -1):
    newPara = newPara.replace('(CUT', '')
    newPara = newPara.replace(' AWAY COMPLETE)', '')
    newPara = newPara.replace(' AWAY TO TITLE)', '')
    newPara = newPara.replace(' BACK TO SIDE)', '')

print(newPara)

prints: 'Empty String'

also:

if (newPara.find('(CUT') != -1):
    for substring in ['(CUT',' AWAY COMPLETE)',' AWAY TO TITLE)', ' BACK TO SIDE)']:
        newPara = newPara.replace(substring, '')

Can the Python .replace() function replace whole phrases?

2 Answers2