Question

Suppose I have a sample array that looks like this:

color_values = [{'score': 3, 'color': u'blue'}, {'score': 1, 'color': u'red'}, {'score': 4, 'color': u'green'}, {'score': 4, 'color': u'red'}, {'score': 2, 'color': u'blue'}]

How do I write a code in python for a new array which averages the score of all the same colors? So the new array would look like:

color_values = [{'score': 2.5, 'color': u'blue'}, {'score': 2.5, 'color': u'red'}, {'score': 4, 'color': u'green'}]

Answer 1

The simplest (if not the shortest) way to solve this kind of problem is to build a dict from the key to a list of values, and then aggregate it:

by_color = {}
for obj in color_values:
    by_color.setdefault(obj['color'], []).append(obj['score'])
color_values = [{'score': float(sum(value)) / len(value), 'color': key}
                for key, value in by_color.items()]