Counter

Resources

• Official collections module documentation.
• Real Python tutorial on Counter.
• Real Python introduction to defaultdict

collections module

The standard library collections module holds some little useful tools like: Counter, OrderedDict or defaultdict.

Counter

Counter is the pythonic way of counting items.

Let’s simulate that we throw a dice 1000 times and then we count the number of times that we get each number.

Exercises

Create a Counter to count how many times each nucleotide appears in a DNA sequence.

Tip

Given a list of words, count how many end in “ing” and how many do not.

Tip

Count the words in a text.

Tip

Count the words in “El Quijote”, you can get the text file from the Gutenberg project. To do it in just one line you might find useful to use nested generator expressions. It might also be useful to have a list with the punctuation signs that you can find in the string module.

Which are the 10 most common words?

Tip

Using zip and Counter count the number of matches and mismatches in two aligned DNA sequences.

Tip