Capitalization of each sentence in a string in Python 3

Question

This should be easy but somehow I\'m not quite getting it.

My assignment is:

Write a function sentenceCapitalizer that has one parameter of type

Answer 1

To allow arbitrary whitespace after the dot. Or to capitalize the full words (It might make the difference for a Unicode text), you could use regular expressions -- re module:

#!/usr/bin/env python3
import re

def sentenceCapitalizer(text):
    return re.sub(r"(\.\s+|^)(\w+)",
                  lambda m: m.group(1) + m.group(2).capitalize(),
                  text)

s = "hEllo. my name is Joe. what is your name?"
print(sentenceCapitalizer(s))
# -> 'Hello. My name is Joe. What is your name?'

Note: pep8 recommends lowercase names for functions e.g., capitalize_sentence() instead of sentenceCapitalizer().

To accept a larger variaty of texts, you could use nltk package:

# $ pip install nltk
from nltk.tokenize import sent_tokenize, word_tokenize 

def sent_capitalize(sentence):
    """Capitalize the first word in the *sentence*."""
    words = word_tokenize(sentence)
    if words:
       words[0] = words[0].capitalize()
    return " ".join(words[:-1]) + "".join(words[-1:]) # dot

text = "hEllo. my name is Joe. what is your name?"
# split the text into a list of sentences
sentences = sent_tokenize(text)
print(" ".join(map(sent_capitalize, sentences)))
# -> Hello. My name is Joe. What is your name?