如何通过密钥对JSON进行分组并按其计数排序? [英] How to group a JSON by a key and sort by its count?

问题描述

我从与此类似的jsonlines文件开始

I start from a jsonlines file similar to this

{ "kw": "foo", "age": 1}
{ "kw": "foo", "age": 1}
{ "kw": "foo", "age": 1}
{ "kw": "bar", "age": 1}
{ "kw": "bar", "age": 1}

请注意，每行都是有效的json，但整个文件不是.

Please note each line is a valid json, but the whole file is not.

我要搜索的输出是按关键字的出现顺序排序的关键字的有序列表.像这样:

The output I'm seeking is an ordered list of keywords sorted by its occurrence. Like this:

[
    {"kw": "foo", "count": 3},
    {"kw": "bar", "count": 2}
]

我可以使用 slurp 选项

jq --slurp '. | group_by(.kw) | .[] | {kw: .[0].kw, count: . | length }'

输出:

{"kw":"bar","count":2}
{"kw":"foo","count":3}

但是:

• 未排序
• 这不是有效的JSON数组

我发现一个非常愚蠢的解决方案是通过 jq :)

A very stupid solution I've found, is to pass twice via jq :)

jq --slurp --compact-output '. | group_by(.kw) | .[] | {kw: .[0].kw, count: . | length }' sample.json \
| jq --slurp --compact-output '. | sort_by(.count)'

但是我敢肯定，比我聪明的人可以找到一个更优雅的解决方案.

But I'm pretty sure someone smarter than me can find a more elegant solution.

推荐答案

未排序

那不是很正确， group_by(.foo)在内部执行 sort(.foo)，因此结果以字段的排序顺序显示.参见 jq 手册-group_by(path_expression)

That is not quite correct, group_by(.foo) internally does a sort(.foo), so the results are shown in the sorted order of the field. See jq Manual - group_by(path_expression)

这不是有效的JSON数组

This is not valid JSON array

只需将操作括在 [..] 中，并且前导.是可选的.所以就做

Just enclose the operation within [..] and also the leading . is optional. So just do

jq --slurp --compact-output '[ group_by(.kw)[] | {kw: .[0].kw, count: length } ]'

如果您是指按 .count 进行排序，则可以进行升序排序和反转

If you are referring to sort by the .count you can do a ascending sort and reverse

jq --slurp --compact-output '[ group_by(.kw)[] | {kw: .[0].kw, count: length }] | sort_by(.count) | reverse'

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