On Jul 20, 2011, at 4:23 PM, gallon li wrote:
I have a 5 column matrix like
12 10 8 6 3
10 9 8 7 5
14 NA 4 NA NA NA
15 NA 10 NA 5
...
Probably something along the lines of
aapply(mtx, 1, function(x) { c( x[ which(x <= 5)[1] ], # first row are
the values
which(x <= 5)[1]) } ) # second row
the positions
--
David.
I want to select the position of the first entry for each row <=5
for example, for the first row, I want to select the last element
and return
its position as 5;
for th e third row, I want to select the third element and return its
position as 3;
similarly for the 4th row, I want to select the fifth element and
return its
position 5.
I am wondering how to do this fast? Thanks a lot!
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