[R] unexpected results

[Huntsinger, Reid]

Yes, that's correct behavior. You are assigning to an extracted submatrix,
and what you're assigning is a vector of length two. This gets "recycled" to
the correct length, which is ten, and fills the submatrix *column-by-column*
(column-major order). 

You probably wanted to iterate x[i,2:3] <- c(1,2) over i. You could use
"rep" to construct the vector like

x[seq(1,10,by=2), 2:3] <- rep(c(1,2),c(5,5))

to get this effect.

Reid Huntsinger



-----Original Message-----
From: Niels Waller [mailto:niels.waller at vanderbilt.edu]
Sent: Wednesday, June 19, 2002 4:26 PM
To: R-Help
Subject: [R] unexpected results




Is R behaving correctly in this example? I do not understand why column 2
has any 2s in it (and why column 3 has any 1s)


> x<-matrix(0,10,3)
> x[seq(1,10,by=2),2:3]<-c(1,2)
> x
      [,1] [,2] [,3]
 [1,]    0    1    2
 [2,]    0    0    0
 [3,]    0    2    1
 [4,]    0    0    0
 [5,]    0    1    2
 [6,]    0    0    0
 [7,]    0    2    1
 [8,]    0    0    0
 [9,]    0    1    2
[10,]    0    0    0

Thank you for any and all help.

(I am using 1.5.0 on Windows NT)

Niels Waller

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