[pkg/ottl] add a function to remove an element from a Slice/Array

[FranPavelic-SB]

Component(s)

pkg/ottl

Is your feature request related to a problem? Please describe.

I'd like there be the ability to also remove elements from slices/arrays, as the inverse of append

Describe the solution you'd like

  transform/test_list_removal:
    error_mode: ignore
    log_statements:
      - conditions:
          - ContainsValue(log.attributes["tags"], "unparsed")
        statements:
          - append(log.attributes["tags"], "parsed")
          - delete(log.attributes["tags"], "unparsed")

Perhaps this is not the most ideal solution to the problem, but I am currently investigating a replacement for a mass log-processing solution and this is a feature we have heavily relied in our rulesets, to handle bits of processing.

Describe alternatives you've considered

I've not been able to infer a solution from the currently available OTTL functions. Perhaps something involving flatten and delete_key, but coming back from flatten is not the clearest either.

Additional context

No response

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[github-actions]

Pinging code owners:

• pkg/ottl: @TylerHelmuth @evan-bradley @edmocosta

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[VihasMakwana]

Thanks for raising this issue.

I have a question:

• How would we handle duplicate elements in a slice? IMO, we can give option to keep/remove duplicates as an optional argument.

I'd love to hear codeowner's thoughts on this.

[edmocosta]

Hi @FranPavelic-SB, thank you for opening this issue.

Do you need to handle duplicate items? If not, I'd started with a delete function that works with indexes/ranges instead of values, so it's more flexible:

delete(target: []any, from: int64, to: Optional[int64])

- delete(attributes["tags"], 0) # delete first
- delete(attributes["tags"], Len(attributes["tags"]) - 1) # delete last
- delete(attributes["tags"], 0, 3) # delete indexes 0, 1 & 2
- delete(attributes["tags"], Index(attributes["tags"], "unparsed")) # delete first occurrence of "unparsed"

If duplicated elements is an issue for your use case, we can probably came up with a different function.
@evan-bradley @TylerHelmuth, please let me know if you have any thoughts.

---

Edit: renamed from remove to delete, so it matches Go's slices.Delete.

[FranPavelic-SB]

I personally have no requirement for handling duplicate items.
remove(target: []any, from: int64, to: Optional[int64]) enables the - remove(attributes["tags"], Index(attributes["tags"], "unparsed")) # delete first occurrence of "unparsed" usecase, which fulfils my use.