which.max command in R

Question

I wrote a code to compute the amount of second data set when the amount of the first data set is maximum but at the end for some latitude and longitude I got very large number which is not in the first data set. Here is the core of the code:

PW.storm <- array(NA,dim=c(length(lon1),length(lat1))) for (i in 1:length(lon1)){ for (j in 1:length(lat1)){ for (k in 1:length(time)){ t <- time.when.dat1.max <- which.max(abs(dat1[i,j,])) PW.storm[i,j] <- abs(dat2[i,j,t]) } } }

Is there a question here? (I heard they typically end with a question mark.) — A5C1D2H2I1M1N2O1R2T1
– A5C1D2H2I1M1N2O1R2T1, Commented Jul 22, 2013 at 17:29
Do note the tie-handling properties of which.max - read ?which.max and try which(x == max(x) as an alternative if you have ties. — Gavin Simpson
– Gavin Simpson, Commented Jul 22, 2013 at 18:05

IRTFM · Accepted Answer · 2013-07-22 17:37:36Z

You code suggests you do not understand what is being returned by which.max. You have:

time.when.dat1.max <- which.max(abs(dat1[i,j,]))

That is not the "time when dat1 is max". It is the index in dat1's third dimension under the conditions of i and j. If times were the values in that third dimension then you would need to use this to get the time values:

 time.when.dat1.max <- dat1[i,j, which.max(abs(dat1[i,j,]))]

If I've guessed wrong about what the dat1 object holds, then you should do a better job of describing the data setup by editing your question.

Collectives™ on Stack Overflow

which.max command in R

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related