Hi,
I have a file with 466,200 lines and 46,000 subjects (there is a
'ident' column for identify subjects, in place 13). I would like to extract from
this file one record by subject.
I created a new column, in place 14, and wrote:
data[1,14]_1
for (i in 1:19999)
{
data[i+1,14]_ifelse(data[i+1,13]==data[i,13],0,1)
}
So if a line corresponds to the same subject as the previous line,
there is a "0" in the new column, and a "1" if this line concerns a
new subject. Endly, I keep only lines with "1".
But I need to repeat this loop for each group of 20,000 lines... it's
so long! Is there a quicker way?
Thank you,
Tristan Lorino
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