Dear R,
I have two small questions confused me recently. Now assume I have a matrix
a, like this,
a - matrix(1:6, 2, 3)
a
[,1] [,2] [,3]
[1,]135
[2,]246
I sometimes need each row of a raised to a different exponent. So I do a
trick like this,
a^c(2, 3)
[,1]
^ is vectorized operator, so
a^c(2,3)
is essentially the same as
a^rep(c(2,3), length.out = length(a))
which is
c(a)^rep(c(2,3), length.out = length(a))
but put back in a matrix format (i.e., with rows and columns).
Now, if you want each column in different power, you need to explicitly
Feng,
Hello, all of this behavior comes down to argument recycling.
Feng Li wrote:
Dear R,
I have two small questions confused me recently. Now assume I have a matrix
a, like this,
a - matrix(1:6, 2, 3)
a
[,1] [,2] [,3]
[1,]135
[2,]246
I sometimes need each
On Sep 7, 2010, at 12:35 PM, Feng Li wrote:
Dear R,
I have two small questions confused me recently. Now assume I have a
matrix
a, like this,
a - matrix(1:6, 2, 3)
a
[,1] [,2] [,3]
[1,]135
[2,]246
I sometimes need each row of a raised to a different
Very fruitful, thanks all of you:)
Feng
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Feng Li feng.li at stat.su.se writes:
Very fruitful, thanks all of you:)
?sweep
may be useful as well (I don't think anyone has mentioned
it yet, sorry if redundant). It handles row/column-wise
operations in a way that is independent of the underlying
column/row ordering or recycling
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