Sorting and Ranking

Order by the value you mean, and remember that sorted returns a new list.

Sorting by a field

key says which part of each row to order by. reverse turns it around. sorted gives you a new list; .sort() changes the one you have and returns None.

rows = [{"name": "Ada", "score": 92}, {"name": "Alan", "score": 79}]
best = sorted(rows, key=lambda r: r["score"], reverse=True)
print([r["name"] for r in best])

The None that catches everyone

names = names.sort() throws your list away and keeps None. It is the single most common list mistake, and nothing raises until you use the result.

names = ["Grace", "Ada"]
print(names.sort())
print(names)
print(sorted(["Grace", "Ada"]))

Exercise

Try It Yourself

Write top_names(rows, n) that returns the names of the n highest scorers, highest first.

def top_names(rows, n):
    # The n highest scorers, best first.
    return []

rows = [{"name": "Ada", "score": 92}, {"name": "Alan", "score": 79}]
print(top_names(rows, 1))

Press Run to see output

Check Your Understanding

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