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Comment: What does the dict_ underscore do?
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| There are many ways to do this. Here's the fastest way to do it, as it avoids using a custom comparison function, instead using builtin comparisons. This is the ''decorate-sort-undecorate'' (DSU) pattern, or the ''Schwartzian transform'' if you're coming from Perl. | There are many ways to do this. Here's the fastest way to do it, as it avoids using a custom comparison function, instead using builtin comparisons. This is the ''decorate-sort-undecorate'' pattern, or the ''Schwartzian transform'' if you're coming from Perl. |
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| == Questions == What does the {{{dict_}}} underscore do? -- LionKimbro |
In case you're wondering, the variable is named `dict_` because we want to have Wiki:MeaningfulNames, but we don't want to shadow the `dict` builtin, so we append an underscore. |
Sorting Lists of Dictionaries
Frequently you want to sort a list of dictionaries, based on some particular key.
For example:
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1 a = {"key1": 5 , "key2": 8, "key3": 2}
2 b = {"key1": 7 , "key2": 4, "key3": 9}
3 c = {"key1": 6 , "key2": 1, "key3": 1}
4 undecorated = [a, b, c] # how do you sort this list?
There are many ways to do this. Here's the fastest way to do it, as it avoids using a custom comparison function, instead using builtin comparisons. This is the decorate-sort-undecorate pattern, or the Schwartzian transform if you're coming from Perl.
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1 sort_on = "key2"
2 decorated = [(dict_[sort_on], dict_) for dict_ in undecorated]
3 decorated.sort()
4 sorted = [dict_ for (key, dict_) in l]
In case you're wondering, the variable is named dict_ because we want to have MeaningfulNames, but we don't want to shadow the dict builtin, so we append an underscore.