Merge two arrays into a single object with jq

Question

I'm trying to use jq to parse a NOAA data feed into just the values I need:

http://forecast.weather.gov/MapClick.php?FcstType=json&lat=39.56&lon=-104.85

I'm able to (separately) extract the two arrays I'm looking to combine:

$ cat noaa.json | jq .time.startPeriodName [ "Today", "Tonight", "Friday", "Friday Night", "Saturday", "Saturday Night", "Sunday", "Sunday Night", "Monday", "Monday Night", "Tuesday", "Tuesday Night", "Wednesday" ] $ cat noaa.json | jq .data.weather [ "Mostly Sunny", "Mostly Cloudy", "Mostly Sunny", "Partly Cloudy", "Slight Chance Showers", "Slight Chance Snow Showers", "Slight Chance Snow Showers then Mostly Sunny", "Mostly Clear", "Mostly Sunny", "Partly Cloudy", "Mostly Sunny", "Partly Cloudy", "Mostly Sunny" ]

I'd like to combine the two arrays together into a single object like this:

{ "Today": "Mostly Sunny", "Tonight": "Mostly Cloudy", ... "Wednesday": "Mostly Sunny" }

I'd be grateful if someone could point me in the right direction. I feel like the answer is probably in the map operator, but I haven't been able to figure it out.

peak · Accepted Answer · 2016-12-08 19:01:50Z

25

Yes, map is a good way to go. The key here is to use it with transpose/0, which can be used as though it were a "zip" function:

 [.time.startPeriodName, .data.weather] | transpose | map( {(.[0]): .[1]})

The output begins as follows:

[ { "Today": "Mostly Sunny" }, { "Tonight": "Mostly Cloudy" }, ...

So, to produce a single JSON object, simply add the add filter to the pipeline.

edited Dec 8, 2016 at 19:01

answered Dec 8, 2016 at 18:48

peak

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5 Comments

Scott Over a year ago

This is helpful. Is there a way I can run transpose and map so that I end up with a single object instead of an array of objects? or perhaps another transformation that can merge this resulting array into a single object?

Scott Over a year ago

Ah, I added | add to the end and got what I wanted.

BSalita Over a year ago

Here's an example that references a path to get to the initial array. jq ".results[0].result.tag | [.classes, .probs] | transpose | map( {(.[0]): .[1]} ) | add" myinput.txt

crackpotHouseplant Over a year ago

The array from which I got my object keys was of the number type, I simply used .[0]|tostring inside the map (e.g. pipe to tostring) following the answer to this question

augurar Over a year ago

Another option to build a dict from a list of pairs is map({key: .[0], value: .[1]}) | to_entries

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