Parallel Arrays to Objects

[vito-c]

input: echo '{"vals":["20","10"],"names":["thing","zip"]}' 
desired output: [ {"val":20,"name":"thing"},{"val":10,"name":"zip"} ]

I have tried a number of things to convert these two arrays into an object but haven't had much luck. I was thinking maybe I could add an index counter and then map off that but I don't even know if there is a way to do that. Thanks :)

[pkoppstein]

def input:{"vals":["20","10"],"names":["thing","zip"]};
def output:
  .vals as $vals | .names as $names
  | reduce range(0; $names|length) as $i
      ([]; . + [{ "val": $vals[$i], "name": $names[$i] }]);

input| output

$ jq -n -c -f unzip.jq
[{"val":"20","name":"thing"},{"val":"10","name":"zip"}]

[ghost]

It seems to me that you're looking for a version of the typical zip function that acts over objects. I once had to do this in JavaScript; maybe it's a good time to release it as a separate library and/or port it to jq!

For obtaining the inputs and outputs you specified, here's a simple jq snippet, using transpose:

jq '[.vals, .names] | transpose | map({"val": .[0], "name": .[1]})'

[vito-c]

@pkoppstein the reduce worked! and it's a great example of how to use the reduce and do some tricky stuff. Thanks!
@slapresta I don't seem to have the transpose function what version of jq is that in? :)

[ghost]

@vito-c No idea when it was introduced, but it's been on master for a while. I seem to recall it being on 1.4, but I'm probably wrong about this.

[wtlangford]

Transpose is new in 1.5, which is currently just master.

On Thu, Oct 30, 2014, 15:51 vito-c notifications@github.com wrote:

@pkoppstein https://github.com/pkoppstein the reduce worked! and it's a
great example of how to use the reduce and do some tricky stuff. Thanks!
@slapresta https://github.com/slapresta I don't seem to have the
transpose function what version of jq is that in? :)

—
Reply to this email directly or view it on GitHub
#609 (comment).

[vito-c]

Ah ic time to: brew update; brew uninstall jq; brew install jq --HEAD

[ghost]

For the record, this one solves the general case:

def zip_object:
    to_entries | sort_by(.key) |
    map(.key) as $keys |
    map(.value) | transpose |
    map(
        [$keys, .] | transpose |
        map({key: .[0], value: .[1]}) | from_entries
    )
;

And you would use it as follows:

jq -n '{"number": ["20", "10", "30"], "stuff": ["thing", "zip", "bacon"], "foo": ["bar", "baz", "quux"]} | zip_object'

[vito-c]

@slapresta where do I need to put these defines so that they are picked up by my commandline jq?

[ghost]

IIRC you could put them at ~/.jq or something like that, although you can just put the definition of the one you need at the beginning of the corresponding command.

[vito-c]

@slapresta is it possible for me add tags to issues? I'd like to look through some of the issues and tag them as examples or use cases

[nicowilliams]

If not let me know what tags for what issues (open an issue for it, even)
and I'll tag them.