Add first/last as one of the built-in aggregate functions for colDef

[C92Anderson]

Hi @glin,

Wondering if it would be possible to add last() and first() as a built-in aggregate function for colDef()? I'm not sure if the custom JS (which I'm not great with) can work with defaultSorted to make this happen so I'm making a request - thanks!

[glin]

Sure, that seems reasonable. In JS, it would also be relatively straightforward to implement, so a custom aggregate function solution could look like this:

data <- MASS::Cars93[14:38, c("Type", "Price", "MPG.city", "DriveTrain", "Man.trans.avail")]

agg_first <- JS("values => values[0]")
agg_last <- JS("values => values[values.length - 1]")

reactable(
  data,
  groupBy = "Type",
  columns = list(
    Price = colDef(aggregate = agg_first),
    DriveTrain = colDef(aggregate = agg_last)
  )
)

But also just to clarify, these would return the first and last elements of the group before sorting, so sorting won't change the results. If you did need the first and last elements after sorting, that'd be more difficult as grouping/aggregation is currently done before sorting. I'm not sure how feasible it would be to enable a sorting-aware aggregation.

[C92Anderson]

Excellent, thank you on both fronts!

…

On Sun, Aug 4, 2024 at 11:33 PM Greg Lin ***@***.***> wrote: Sure, that seems reasonable. In JS, it would also be relatively straightforward to implement, so a custom aggregate function solution could look like this: data <- MASS::Cars93[14:38, c("Type", "Price", "MPG.city", "DriveTrain", "Man.trans.avail")] agg_first <- JS("values => values[0]")agg_last <- JS("values => values[values.length - 1]") reactable( data, groupBy = "Type", columns = list( Price = colDef(aggregate = agg_first), DriveTrain = colDef(aggregate = agg_last) ) ) But also just to clarify, these would return the first and last elements of the group *before* sorting, so sorting won't change the results. If you did need the first and last elements after sorting, that'd be more difficult as grouping/aggregation is currently done before sorting. I'm not sure how feasible it would be to enable a sorting-aware aggregation. — Reply to this email directly, view it on GitHub <#387 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACAO5NUQ677WOHGQNIG6TCDZP3XB3AVCNFSM6AAAAABL2X4LVWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDENRYGEYDMMJVGQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>