yq/pkg/yqlib/doc/operators/slice-array.md

Slice/Splice Array

The slice array operator takes an array as input and returns a subarray. Like the jq equivalent, .[10:15] will return an array of length 5, starting from index 10 inclusive, up to index 15 exclusive. Negative numbers count backwards from the end of the array.

You may leave out the first or second number, which will will refer to the start or end of the array respectively.

Slicing arrays

Given a sample.yml file of:

- cat
- dog
- frog
- cow

then

yq '.[1:3]' sample.yml

will output

- dog
- frog

Slicing arrays - without the first number

Starts from the start of the array

Given a sample.yml file of:

- cat
- dog
- frog
- cow

then

yq '.[:2]' sample.yml

will output

- cat
- dog

Slicing arrays - without the second number

Finishes at the end of the array

Given a sample.yml file of:

- cat
- dog
- frog
- cow

then

yq '.[2:]' sample.yml

will output

- frog
- cow

Slicing arrays - use negative numbers to count backwards from the end

Given a sample.yml file of:

- cat
- dog
- frog
- cow

then

yq '.[1:-1]' sample.yml

will output

- dog
- frog

Inserting into the middle of an array

using an expression to find the index

Given a sample.yml file of:

- cat
- dog
- frog
- cow

then

yq '(.[] | select(. == "dog") | key + 1) as $pos | .[0:($pos)] + ["rabbit"] + .[$pos:]' sample.yml

will output

- cat
- dog
- rabbit
- frog
- cow