Boston Python Workshop 8/Loops: Difference between revisions

=== Building up a list ===

Sometimes you want to build up a new list based on information about each element in an existing list. To do this, initialize an empty list before the <code>for</code> loop, and append elements to the new list inside the <code>for</code> loop:

=== Using a counter ===

Sometimes you want to keep track of the number of occurrences of something, or a running total, as you loop through a list. To do this, initialize a variable before the <code>for</code> loop that you update inside the <code>for</code> loop:

<pre>

>>> prices = [1.5, 2.35, 5.99, 16.49]

>>> total = 0

>>> for price in prices:

... total = total + price

...

>>> total

26.33</pre>