Sams Teach Yourself Perl in 21 Days, Second Edition

An Example: Frequencies in the Statistics Program

Let's modify our statistics script again, this time to add a feature that keeps track of the number of times each number appears in the input data. We'll use this feature to print out a histogram of the frequencies of each bit of data. Here's an example of what that histogram will look like (other than the histogram, the output the script produces is the same as it was before, so I'm not going to duplicate that here):

Frequency of Values:
1  | *****
2  | *************
3  | *******************
4  | ****************
5  | ***********
6  | ****
43 | *
62 | *

To keep track of each number's frequency in our script, we use a hash, with the keys being the actual numbers in the data and the values being the ...