Python：合并统计数据 [英] Python: merging tally data

问题描述

好吧，我确信这已经在这里回答过了，但我找不到它....

Okay - I'm sure this has been answered here before but I can't find it....

我的问题：我有一个列表与此组合

My problem: I have a list of lists with this composition

0.2 A

0.1 A

0.3 A

0.3 B

0.2 C

0.5 C

我的目标是输出以下内容：

My goal is to output the following:

0.6 A

0.3 B

0.7 C

换句话说，我需要将数据合并在一起。

In other words, I need to merge the data from multiple lines together.

这是我使用的代码：

unique_percents = []

for line in percents:
    new_percent = float(line[0])
    for inner_line in percents:
        if line[1] == inner_line[1]:
           new_percent += float(inner_line[0])
        else:
            temp = []
            temp.append(new_percent)
            temp.append(line[1])
            unique_percents.append(temp)
            break

我认为它应该可以工作，但它不是添加百分比，仍然有重复。也许我不明白休息如何运作？

I think it should work, but it's not adding the percents up and still has the duplicates. Perhaps I'm not understanding how "break" works?

我还将提出一个更好的循环结构或算法来使用。谢谢大卫。

I'll also take suggestions of a better loop structure or algorithm to use. Thanks, David.

推荐答案

你想使用一个dict，但是 collections.defaultdict 可以非常方便地在这里，所以你不必担心该键是否存在于dict中 - 它默认为0.0：

You want to use a dict, but collections.defaultdict can come in really handy here so that you don't have to worry about whether the key exists in the dict or not -- it just defaults to 0.0:

import collections

lines = [[0.2, 'A'], [0.1, 'A'], [0.3, 'A'], [0.3, 'B'], [0.2, 'C'], [0.5, 'C']]
amounts = collections.defaultdict(float)
for amount, letter in lines:
    amounts[letter] += amount

for letter, amount in sorted(amounts.iteritems()):
    print amount, letter

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