dtUngroup <- function(DT){
colClasses <- lapply(DT,FUN=class)
listCols <- which(colClasses=='list')
if(length(listCols)>0){
nonListCols <- setdiff(colnames(DT),listCols)
nbListElem <-
unlist(DT[,lapply(.SD,FUN=lengths),.SDcols=(listCols[1L])])
DT1 <-
DT[,lapply(.SD,FUN=rep,times=(nbListElem)),.SDcols=(nonListCols)]
DT1[,(listCols):=DT[,lapply(.SD,FUN=function(x)
do.call('c',x)),.SDcols=(listCols)]]
return(DT1)
}
return(DT)
}
This works... still 20x slower than the equivalent in kdb
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