jq how to merge multiple arrays?

Question

I have the following data, the output of multiple jq pipes:

 [
   {
     "Russia": 1073849
   }
 ]
 [
   {
     "Spain": 593730
   }
 ]
 [
   {
     "France": 387252
   }
 ]
 [
   {
     "UK": 371125
   }
 ]

My desired output is:

 [
   {
     "Russia": 1073849
   },
   {
     "Spain": 593730
   },
   {
     "France": 387252
   },
   {
     "UK": 371125
   }
 ]

Based on similar questions I tried '.[]|transpose|map(add)' and it gives an error: Cannot index object with number. Also I cannot group_by(key) because there is no common key in the objects.

Answer 1

Assuming input.json file is:

[{"Russia": 1073849}]
[{"Spain": 593730}]
[{"France": 387252}]
[{ "UK": 371125}]

Then this:

jq -s 'reduce .[] as $x ([]; . + $x)' input.json

returns:

[
  {
    "Russia": 1073849
  },
  {
    "Spain": 593730
  },
  {
    "France": 387252
  },
  {
    "UK": 371125
  }
]

Notes:

• jq can merge arrays with the + operator, e.g. [1]+[2] returns [1,2].
• The -s flag reads input.json and put all entries into an array. So you end up with an array of arrays that you can merge with reduce.

This can be simplified even further with:

jq -s 'add' input.json