Thank you very much for the help. I decided to go with the 'plyr' package but
it is nice to have options.
Have a lovely day.
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Hi,
I have a matrix that looks like this
a - c(1,1,1,1,2,2,3,3,3,3)
b - c(2,2,2,3,4,4,4,5,5,6)
c - c(1,2,3,4,5,6,7,8,9,10)
M - matrix(nr=10,nc=3)
M[,1] - a
M[,2] - b
M[,3] - c
M
[,1] [,2] [,3]
[1,]121
[2,]122
[3,]123
[4,]13
one way is the following:
M - cbind(c(1,1,1,1,2,2,3,3,3,3), c(2,2,2,3,4,4,4,5,5,6),
c(1,2,3,4,5,6,7,8,9,10))
ind - do.call(paste, c(as.data.frame(M[, 1:2], sep = \r)))
M[, 3] - ave(M[, 3], ind, FUN = sum)
unique(M)
I hope it helps.
Best,
Dimitris
On 9/6/2010 4:29 PM, Kennedy wrote:
On Mon, Sep 6, 2010 at 3:29 PM, Kennedy henrik.aldb...@gmail.com wrote:
I want to reduce the matrix according to the following: If the values of the
two first columns are the same in two or more rows the values in the third
column of the corresponding rows should be added and only one of the
On Sep 6, 2010, at 10:47 AM, Dimitris Rizopoulos wrote:
one way is the following:
M - cbind(c(1,1,1,1,2,2,3,3,3,3), c(2,2,2,3,4,4,4,5,5,6),
c(1,2,3,4,5,6,7,8,9,10))
ind - do.call(paste, c(as.data.frame(M[, 1:2], sep = \r)))
M[, 3] - ave(M[, 3], ind, FUN = sum)
unique(M)
I had been
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