I want to split a list into parts based on a condition Examp

Question

I want to split a list into parts based on a condition Example Split on even numbers ``` val input = listOf 4 1 1 3 2 5 2 val output = input chunkedBy it 2 == 0 should be 4 1 1 3 2 5 2 ``` Is there such a thing in the standard library

nfrankel · Answer

did you try `groupBy ` <https kotlinlang org api latest jvm stdlib kotlin collections group by html>

diesieben07 · Answer

`groupBy` returns a Map though

nfrankel · Answer

true

nfrankel · Answer

but it s then quite easy to get its values and put it into a list or an array

spand · Answer

` values` or do you absolutely need a `List`

diesieben07 · Answer

Yes I need a list And I also need the order preserved

diesieben07 · Answer

groupBy does not help me here at all it stuffs things into a bag by a condition

diesieben07 · Answer

I need to split based on a condition

nfrankel · Answer

ok then sorry i don t know the stdlib well enough to help you there

nfrankel · Answer

disappointed

diesieben07 · Answer

That s okay

nfrankel · Answer

`chunked ` is based on size

nfrankel · Answer

nfrankel · Answer

seems like it should work for you

spand · Answer

I guess `fold` is the closest you can get

diesieben07 · Answer

`partition` only checks a boolean condition

rrader · Answer

condition only boolean can be

rrader · Answer

``` val input = listOf 4 1 1 3 2 5 2 println input partition it 2 == 0 ```

diesieben07 · Answer

That does not do what I want even remotely

diesieben07 · Answer

It shoves all even numbers in one list and uneven ones in the other That is not what I need

rrader · Answer

but what do you need in message you wrote Split on even numbers

diesieben07 · Answer

See example input gt output above

rrader · Answer

and what is condition in that example

diesieben07 · Answer

It specifies the element to split on

diesieben07 · Answer

Every even number should start a new list

Richard Green · Answer

What if the first n elements n gt 0 are not true for the condition

Richard Green · Answer

if one simplifies it to t rue and f alse then is the output of the form f tf

fitzoh · Answer

so basically a repeated `takeWhile`

diesieben07 · Answer

Correct

diesieben07 · Answer

gt What if the first n elements n gt 0 are not true for the condition Then they would be in their own group I want behavior like String split

hho · Answer

Ugly but seems to work <https try kotlinlang org UserProjects hvruqbrvlhmdbms8mp374cj3ad i0nf1m4h6iusd4u3d061usmk9q>

karelpeeters · Answer

`condition invoke it ` gt `condition it `

diesieben07 · Answer

thats exactly what I wrote for myself smile

diesieben07 · Answer

except i used for in

karelpeeters · Answer

Out of interest what is the use case

diesieben07 · Answer

Parsing a terrible XML document I get a list of text blocks intermitted with lt audio gt elements The lt audio gt elements specify which audio file to use for the following text blocks

hho · Answer

< karelpeeters> Fixed But as I said It s ugly

diesieben07 · Answer

I want to parse it into groups of audio+list of text