Hello,
i am trying to subset a dataframe multiple times:
something like:
stats <- by(df, list(items), ttestData)
ttestData <- function(df){
t.test( df[,c(2,3,4), df[,c(5,6,7)]
}
While this works for small data, it is to slow for my
actual data: 500000 rows dataframe with
about 135000 different indices, subsetting the
dataframe into chunks of 5 on average.
Do you have any suggestions how I could speed this up?
I tried changing to call by reference with
the package ref, but by does not like that.
Thank you very much in advance
Ido Tamir
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