Pick

Filter a map by the specified list of keys. Map is returned with the key in the order of the pick list.

Similarly, filter an array by the specified list of indices.

Pick keys from map

Note that the order of the keys matches the pick order and non existent keys are skipped.

Given a sample.yml file of:

myMap:
  cat: meow
  dog: bark
  thing: hamster
  hamster: squeak

then

yq '.myMap |= pick(["hamster", "cat", "goat"])' sample.yml

will output

myMap:
  hamster: squeak
  cat: meow

We create a map of the picked keys plus all the current keys, and run that through unique

Given a sample.yml file of:

myMap:
  cat: meow
  dog: bark
  thing: hamster
  hamster: squeak

then

yq '.myMap |= pick( (["thing"] + keys) | unique)' sample.yml

will output

myMap:
  thing: hamster
  cat: meow
  dog: bark
  hamster: squeak

Note that the order of the indices matches the pick order and non existent indices are skipped.

Given a sample.yml file of:

- cat
- leopard
- lion

then

yq 'pick([2, 0, 734, -5])' sample.yml

will output

- lion
- cat