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Confusing error message when trying to group by a list column #4308

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sindribaldur opened this issue Mar 19, 2020 · 0 comments · Fixed by #4309
Closed

Confusing error message when trying to group by a list column #4308

sindribaldur opened this issue Mar 19, 2020 · 0 comments · Fixed by #4309
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non-atomic column e.g. list columns, S4 vector columns
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@sindribaldur
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sindribaldur commented Mar 19, 2020

iis <- data.table(iris)
iis[, letts := .(list(sample(letters[1:4], size = 2))), 1:nrow(iris)]
iis[, .N, .(Species, letts)]

Error in `[.data.table`(iis, , .N, .(Species, letts)) : 
  column or expression 2 of 'by' or 'keyby' is type list. Do not quote column names. Usage: DT[,sum(colC),by=list(colA,month(colB))]

"Do not quote column names" seems out of place.

@sindribaldur sindribaldur changed the title Cofnusing error message when trying to group by a list column Confusing error message when trying to group by a list column Mar 20, 2020
@jangorecki jangorecki added the non-atomic column e.g. list columns, S4 vector columns label Apr 5, 2020
@mattdowle mattdowle added this to the 1.14.1 milestone Jun 14, 2021
@jangorecki jangorecki modified the milestones: 1.14.9, 1.15.0 Oct 29, 2023
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