arraysjsonconcatenationjq

How to combine lists on the command line (jq)?

I have two files with JSON lists:

File 1

[0,1,2]
["a", "b", "c"]

File 2

[3,4,5]
["d", "e", "f"]

How can I use jq or a similar command line tool to combine the lists in each line? The result from combining the two files above should be :

[0,1,2,3,4,5]
["a", "b", "c", "d", "e", "f"]
Solution

  • Read both files into an array, use transpose to combine by their index, and perform the operation on the resulting array, i.e. add the subarrays.

    jq -nc --slurpfile f1 file1.json --slurpfile f2 file2.json \
  '[$f1, $f2] | transpose[] | add'

    Alternatively, read them into one array, and split that single array in half to produce the two subarrays:

    jq -sc '[.[:length/2], .[length/2:]] | transpose[] | add' file1.json file2.json

    Output:

    [0,1,2,3,4,5]
["a","b","c","d","e","f"]