Python: Split string into substrings of a certain length BUT don't split a word [duplicate]

Question

I have some long strings that I would like to split up into substrings of a certain length.

The catch is that the long strings are paragraphs, and I would not like to break up words.

I have this code so far, which does split up words:

my_string = 'this is a test sentence'
n=10
chunks = [my_string[i:i+n] for i in range(0, len(my_string), n)]
print(chunks)

result:

['this is a ', 'test sente', 'nce']

I would like the result to be ['this is a ', 'test ', 'sentence'] (aka, if it has to cut into a word then cut before the word instead).

(In the real script the chunks would be 200 characters long so there would be no possible issue of a word being longer than the chunk size).

Any ideas? This is a really tricky one!!

Answer 1

Try the following:

my_string = 'this is a test sentence'
n = 10

def chunk(s, n):
    i = 0
    result = []
    while True:
        start = i
        i += n
        
        # At end of string
        if i >= len(s):
            result.append(s[start:i])
            return result
        
        # Back up until space
        while s[i - 1] != ' ':
            i -= 1
        result.append(s[start:i])

print(chunk(my_string, n))
# ['this is a ', 'test ', 'sentence']