Francesco Napolitano wrote:
Il giorno mer, 23/12/2009 alle 22.14 -0500, David Winsemius ha scritto:
for(i in 1:n){
submat <- data[1:i,]
C <- colSums(submat)
}
In R the loop is not necessary, even confusing as you are demonstrating:
> mat <- matrix(rnorm(100), nrow=10) # 10 x 10
> colSums(mat[1:5, ]) # sums of 1st 5 rows
[1] 3.33331735 0.86672248 -3.10971483 1.23620455 -0.31887421
-0.50544837
[7] 3.13636155 0.02175862 -2.18816961 -1.31760196
It would be unnecessary also in Matlab. In the real code I need to store
the partial sums (the example overwrites them, so it looks like wasted
loops).
try:
data <- matrix(rnorm(100), nrow=10) # 10 x 10
apply(data,2,cumsum)
if you want to store the partial sums
(that was an important bit of information you left out)
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