You should attempt the previous exercises before you go on. You can download my solution from http://thinkpython.com/code/analyze_book.py. You will also need http://thinkpython.com/code/emma.txt.
Here is a program that reads a file and builds a histogram of the words in the file:
import string def process_file(filename): hist = dict() fp = open(filename) for line in fp: process_line(line, hist) return hist def process_line(line, hist): line = line.replace('-', ' ') for word in line.split(): word = word.strip(string.punctuation + string.whitespace) word = word.lower() hist[word] = hist.get(word, 0) + 1 hist = process_file('emma.txt')
This program reads
emma.txt, which contains the text of Emma by Jane Austen.
process_file loops through the lines of the file, passing them one at a time to
process_line. The histogram
hist is being used as an accumulator.
process_line uses the string method
replace to replace hyphens with spaces before using
split to break the line into a list of strings. It traverses the list of words and uses
lower to remove punctuation and convert to lower case. (It is a shorthand to say that strings are “converted;” remember that string are immutable, so methods like
lower return new strings.)
process_line updates the histogram by creating a new item or incrementing an existing one.
To count the total number of words in the file, we can add up the frequencies in the histogram:
def total_words(hist): return sum(hist.values())
The number of different words is just the number of items in the dictionary:
def different_words(hist): return len(hist)
Here is some code to print the results:
print 'Total number of words:', total_words(hist) print 'Number of different words:', different_words(hist)
And the results:
Total number of words: 161080 Number of different words: 7214