Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Python Python Collections (Retired) Dictionaries Word Count

Gary Gibson
Gary Gibson
5,011 Points

I don't undertand why this code is adding anything to the empty dict.

I had to look up the correct answer to this code challenge. I get that an empty dict has been set up (a_dict = {}). I get that the count is being incremented in the for loop (for word in a_string.split()... += 1 or = 1).

What I don't get is WHY this adds anything to the empty a_dict!!!

def word_count(a_string):
    a_dict = {}
    for word in a_string.split():
        if word in a_dict:
            a_dict[word] += 1
        else:
            a_dict[word] = 1
    return a_dict
word_count.py
# E.g. word_count("I am that I am") gets back a dictionary like:
# {'i': 2, 'am': 2, 'that': 1}
# Lowercase the string to make it easier.
# Using .split() on the sentence will give you a list of words.
# In a for loop of that list, you'll have a word that you can
# check for inclusion in the dict (with "if word in dict"-style syntax).
# Or add it to the dict with something like word_dict[word] = 1.

def word_count(a_string):
  a_dict = {}
  for word in a_string.split(" "):

2 Answers

Kourosh Raeen
Kourosh Raeen
23,732 Points

The line: a_dict[word] = 1 adds a new entry to a_dict with word as the key and 1 as the value.