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December 14, 2015 11:38
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Error message from using data.table on a very wide dataset
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rm(dtt) ## Make sure `dtt` isn't there to begin with | |
set.seed(1) | |
LLLL <- apply(expand.grid(LETTERS, LETTERS[10:15], LETTERS[1:20], LETTERS[1:5], stringsAsFactors=FALSE), 1, paste0, collapse="") | |
size <- 1000 | |
dateSamples <- 1500 | |
startDate <- as.Date("1980-01-01") | |
Name <- apply(matrix(LLLL[1:(2*size)], ncol=2), 1, paste0, collapse="") | |
Code <- sample(1e3:max(1e4-1, size+1e3), length(Name)) | |
CURRENCY <- sample(c("USD", "EUR", "YEN"), length(Name), TRUE) | |
Dates <- seq(startDate, length.out=dateSamples, by="mon") | |
Values <- sample(c(1:1e2, 1:5e2), size=size*dateSamples, TRUE) / 1e2 | |
# Calling the sample dataframe `data` to keep consistency, but I dont like this practice | |
data <- data.frame(Name, Code, CURRENCY, | |
matrix(Values, ncol = length(Dates), | |
dimnames = list(c(), as.character(Dates)))) | |
library(data.table) | |
dtt <- data.table(data) | |
# non value columns, ie, the columns to keep post reshape | |
nvc <- c("Name","Code", "CURRENCY") | |
# name of columns being transformed | |
dateCols <- setdiff(names(data), nvc) | |
# use rbind list to combine subsets | |
#+------------------------------------+# | |
# WARNING MESSAGE # | |
#+------------------------------------+# | |
dtt2 <- rbindlist(lapply(dateCols, function(d) { | |
dtt[, Date := d] | |
cols <- c(nvc, "Date", d) | |
setnames(dtt[, cols, with=FALSE], cols, c(nvc, "Date", "value")) | |
})) | |
#+------------------------------------------------+# | |
# NO WARNING MESSAGE # | |
# Probably because `dtt` has already been modified # | |
#+------------------------------------------------+# | |
dtt3 <- rbindlist(lapply(dateCols, function(d) { | |
dtt[, Date := d] | |
cols <- c(nvc, "Date", d) | |
setnames(dtt[, cols, with=FALSE], cols, c(nvc, "Date", "value")) | |
})) |
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