yq/pkg/yqlib/doc/operators/subtract.md
Abel Sen fa6fac1a76
Minor typos (#1595)
* Remove extra backtick

* Reword explanation of update

* Reword explanation of relative update

* Change "remaple" to "remain"

* Change "clovver" to "clobber"

* Reword explanation of update for comment operators

* Reword explanation of relative update for comment operators

* Change "array" to "expression"

* Change "the golangs" to "Golang's"

* Change "golangs" to "Golang's"

* Change "can durations" to "can add durations"

* Change "array scalars" to "arrays"

* Change "beit" to "be it"

* Fix typo in `eval` tip

* Fix typo in header for `has` operation

* Add space before pipe in `line` operator example

* Fix typos in explanation of deep array merges

* Change "is now used" to "is now used."

* Change "object," to "object."

* Changes "indexes" to "indices"

* Remove extraneous copied text from `..` article

* Reword explanation of `...` operator

* Change "your are" to "you are"

* Add link to `string` operator docs in `select` article

* Change "is a" to "parameter specifies" in `string` operators article

* Change "new line" to "newline"

* Change "golang regex" to "Golang's regex"

* Change "golang" to "Golang"

* Add period

* Remove comma in `subtract` article

* Remove duplicate number subtraction example

* Remove comma in `traverse` operator article

* Clarify use of brackets when `read`ing with special characters
2023-03-16 13:39:36 +11:00

2.2 KiB

Subtract

You can use subtract to subtract numbers as well as remove elements from an array.

Array subtraction

Running

yq --null-input '[1,2] - [2,3]'

will output

- 1

Array subtraction with nested array

Running

yq --null-input '[[1], 1, 2] - [[1], 3]'

will output

- 1
- 2

Array subtraction with nested object

Note that order of the keys does not matter

Given a sample.yml file of:

- a: b
  c: d
- a: b

then

yq '. - [{"c": "d", "a": "b"}]' sample.yml

will output

- a: b

Number subtraction - float

If the lhs or rhs are floats then the expression will be calculated with floats.

Given a sample.yml file of:

a: 3
b: 4.5

then

yq '.a = .a - .b' sample.yml

will output

a: -1.5
b: 4.5

Number subtraction - int

If both the lhs and rhs are ints then the expression will be calculated with ints.

Given a sample.yml file of:

a: 3
b: 4

then

yq '.a = .a - .b' sample.yml

will output

a: -1
b: 4

Decrement numbers

Given a sample.yml file of:

a: 3
b: 5

then

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

will output

a: 2
b: 4

Date subtraction

You can subtract durations from dates. Assumes RFC3339 date time format, see date-time operators for more information.

Given a sample.yml file of:

a: 2021-01-01T03:10:00Z

then

yq '.a -= "3h10m"' sample.yml

will output

a: 2021-01-01T00:00:00Z

Date subtraction - custom format

Use with_dtf to specify your datetime format. See date-time operators for more information.

Given a sample.yml file of:

a: Saturday, 15-Dec-01 at 6:00AM GMT

then

yq 'with_dtf("Monday, 02-Jan-06 at 3:04PM MST", .a -= "3h1m")' sample.yml

will output

a: Saturday, 15-Dec-01 at 2:59AM GMT

Custom types: that are really numbers

When custom tags are encountered, yq will try to decode the underlying type.

Given a sample.yml file of:

a: !horse 2
b: !goat 1

then

yq '.a -= .b' sample.yml

will output

a: !horse 1
b: !goat 1