Capitalize each first word of a sentence in a paragraph

Question

I want to capitilize the first word after a dot in a whole paragraph (str) full of sentences. The problem is that all chars are lowercase.

I tried something like this:

text = "here a long. paragraph full of sentences. what in this case does not work. i am lost" 
re.sub(r'(\b\. )([a-zA-z])', r'\1' (r'\2').upper(), text) 

I expect something like this:

"Here a long. Paragraph full of sentences. What in this case does not work. I am lost."

Answer 1

You can use re.sub with a lambda:

import re
text = "here a long. paragraph full of sentences. what in this case does not work. i am lost" 
result = re.sub('(?<=^)\w|(?<=\.\s)\w', lambda x:x.group().upper(), text)

Output:

'Here a long. Paragraph full of sentences. What in this case does not work. I am lost'

Regex Explanation:

(?<=^)\w: matches an alphanumeric character preceded by the start of the line.

(?<=\.\s)\w: matches an alphanumeric character preceded by a period and a space.