29 lines
774 B
Markdown
29 lines
774 B
Markdown
---
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title: combine_values
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tags: dictionary,intermediate
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---
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Combines two or more dictionaries, creating a list of values for each key.
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- Create a new `collections.defaultdict` with `list` as the default value for each key and loop over `dicts`.
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- Use `dict.append()` to map the values of the dictionary to keys.
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- Use `dict()` to convert the `collections.defaultdict` to a regular dictionary.
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```py
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from collections import defaultdict
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def combine_values(*dicts):
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res = defaultdict(list)
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for d in dicts:
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for key in d:
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res[key].append(d[key])
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return dict(res)
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```
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```py
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d1 = {'a': 1, 'b': 'foo', 'c': 400}
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d2 = {'a': 3, 'b': 200, 'd': 400}
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combine_values(d1, d2) # {'a': [1, 3], 'b': ['foo', 200], 'c': [400], 'd': [400]}
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```
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