Tkinter GUI Application Development Blueprints, Second Edition - Second Edition

Using filter and map

Python provides two built-in functions, named filter and map, to manipulate collections directly rather than having to iterate over each item in the collection. The filter, map, and reduce functions are faster than loops because a lot of the work is done by the underlying code written in C.

The filter(function, list) function returns a list (iterators in Python 3.x) that contains all the items for which the function returns a true value. The following command is an example:

print filter(lambda num: num>6, range(1,10))# prints [7, 8,9]

This is faster than running a conditional if-then check against the list.

The map(function_name, list) function applies function_name to each item in the list and returns the values in a ...