You access columns of a data.frame by column indices as in: X[ ,1], X[ ,2],
etc. The index before the comma would stand for the row if you wanted to
restrict those. The index after the comma captures the column.
That said, you typically would not extract rows from the data frame but
draw directly
Hi,
I converted an Excel file into a .txt file X.txt with no header (
http://r.789695.n4.nabble.com/file/n3908157/X.txt X.txt ) and imported it
with:
X - read.table(/Users/johnlogandurland/Desktop/X.txt, header=FALSE).
What I would like to do is to make the first column into a factors vector,
Hi Daniel,
Thanks for the reply, that was the one missing piece! I had been trying to
use the tapply() function, but was getting an error message about unequal
length until now.
I wrote:
VAL_mean_xpart - tapply(X[ ,2], PARTF, mean)
and got the column 2 means by factors just as I had hoped.
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