使用多个键合并python字典列表

问题描述

我想使用多个键合并两个词典列表.

I want to merge two lists of dictionaries, using multiple keys.

我只有一个字典，其中有一组结果:

I have a single list of dicts with one set of results:

l1 = [{'id': 1, 'year': '2017', 'resultA': 2},
      {'id': 2, 'year': '2017', 'resultA': 3},
      {'id': 1, 'year': '2018', 'resultA': 3},
      {'id': 2, 'year': '2018', 'resultA': 5}]

以及另一组用于另一组结果的字典:

And another list of dicts for another set of results:

l2 = [{'id': 1, 'year': '2017', 'resultB': 5},
      {'id': 2, 'year': '2017', 'resultB': 8},
      {'id': 1, 'year': '2018', 'resultB': 7},
      {'id': 2, 'year': '2018', 'resultB': 9}]

我想使用'id'和'year'键将它们结合起来以得到以下内容:

And I want to combine them using the 'id' and 'year' keys to get the following:

all = [{'id': 1, 'year': '2017', 'resultA': 2, 'resultB': 5},
       {'id': 2, 'year': '2017', 'resultA': 3, 'resultB': 8},
       {'id': 1, 'year': '2018', 'resultA': 3, 'resultB': 7},
       {'id': 2, 'year': '2018', 'resultA': 5, 'resultB': 9}]

我知道，要在一个键上组合两个字典列表，可以使用以下方法:

I know that for combining two lists of dicts on a single key, I can use this:

l1 = {d['id']:d for d in l1}

all = [dict(d, **l1.get(d['id'], {})) for d in l2]

但是它忽略了年份，并提供了以下不正确的结果:

But it ignores the year, providing the following incorrect result:

all = [{'id': 1, 'year': '2018', 'resultA': 3, 'resultB': 5},
       {'id': 2, 'year': '2018', 'resultA': 5, 'resultB': 8},
       {'id': 1, 'year': '2018', 'resultA': 3, 'resultB': 7},
       {'id': 2, 'year': '2018', 'resultA': 5, 'resultB': 9}]

像在R中那样处理它，通过添加要合并的第二个变量，我得到一个KeyError:

Treating this as I would in R, by adding in the second variable I want to merge on, I get a KeyError:

l1 = {d['id','year']:d for d in l1}

all = [dict(d, **l1.get(d['id','year'], {})) for d in l2]

如何使用多个键合并?

推荐答案

使用元组(d['id'], d['year'])作为密钥，而不是d['id','year'].

Instead of d['id','year'], use the tuple (d['id'], d['year']) as your key.

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