Why are you doing this iteratively? Can't you load all the files into a
list, rbindlist and then reshape?
On 18/12/13 09:04, Huashan Chen wrote:
OK, here is the complete code with some mock functions from my example.
# data: data.table object
# fn: a filename to read data from
merge_data<-function(fn, data){
fs<-getSavedata(fn) # read as data.frame
if (is.null(fs)) stop('Empty data file')
# return a character vector of variable names which are to merged, some
variables in fs will not be merged to DT
newvars<-selectVars(names(fs))
stopifnot(length(newvars) > 0)
# determine which rows to use
caseid<-someCustomFunc(fs)
add_var<-function(varname){
data[caseid, `:=`(eval(substitute(varname)), fs[,
toupper(eval(substitute(varname)))]), with=F]
}
invisible(sapply(newvars, add_var))
}
# calling function
merge_data('some file', DT)
DT # display the updated results
In this case, I think a warning from merge_data() when the quota is reached
would be appreciated. Of couse, I could have added a check within the
function to avoid unintended action.
if (truelength(data) <= ncol(data) + 64L) stop('increase colunmn quota
using alloc.col() before calling this function.')
--
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