Slight improvement on my earlier attempt.
##================================================
library(data.table)
DT <- fread("raw.data.csv")
mydate <- DT[ , date]
mydate <- rep(mydate, 2)
id <- rep(c("ABC", "DEF"), each = 10)
DT1 <- DT[, date := NULL]
num_chunks <- ncol(DT1) / 4
cols_per_chunk <- 4
DT2 <- split_df <- split.default(DT1, rep(1:num_chunks, each =
cols_per_chunk))
names(DT2[[1]]) <- names(DT2[[2]]) <- c("price1", "vol1", "price2","vol2")
DT2 <- rbindlist(DT2)
DT2 <- cbind(DT2, mydate, id)
##=================================================
On Wed, 18 Jun 2025 at 16:00, Ivan Krylov via R-help <r-help@r-project.org>
wrote:
> В Wed, 18 Jun 2025 10:27:37 +0000
> Naresh Gurbuxani <naresh_gurbux...@hotmail.com> пишет:
>
> > mydt <- data.table(
> > date = seq(as.IDate("2025-06-01"), by = 1, length.out = 10),
> > ABC1_price = runif(10, 100, 120), ABC1_volume = runif(10, 200, 300),
> > ABC2_price = runif(10, 100, 120), ABC2_volume = runif(10, 200, 300),
> > DEF1_price = runif(10, 100, 120), DEF1_volume = runif(10, 200, 300),
> > DEF2_price = runif(10, 100, 120), DEF2_volume = runif(10, 200, 300))
> >
> > mydt[
> > , let(ABC_price = fifelse(ABC1_volume < ABC2_volume, ABC2_price,
> > ABC1_price),
> > DEF_price = fifelse(DEF1_volume < DEF2_volume, DEF2_price,
> > DEF1_price)) ]
>
> Thank you for the reproducible example! How about the following?
>
> for (var in c("ABC", "DEF")) mydt[,
> price := fifelse(volume1 < volume2, price2, price1),
> env = list(
> price = paste0(var, '_price'),
> price1 = paste0(var, '1_price'),
> price2 = paste0(var, '2_price'),
> volume1 = paste0(var, '1_volume'),
> volume2 = paste0(var, '2_volume')
> )
> ]
>
> --
> Best regards,
> Ivan
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
>
--
John Kane
Kingston ON Canada
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