this is what my program read
dataa<-data.frame(matrix(0, nrow=nrow(data), ncol=ncol(data))
i<-1
j<-1
while(i<=nrow(data))
{
if(data$Index.Price==1)
data1[j,]<-data[i,]
else
{
num<-data$No.Primary[i]
data[j,]<-apply(data[i:i+num-1,],2,sum)
i<-i+num-1
}
j<-j+1
PROTECTED]
Subject: [R] more efficient sum of matrix columns
Dear R users,
I am looking for a more efficient way to compute the sum of columns of
a
matrix.
I am currently using apply(data, 2, sum) however, I am building a data
set
from another one by summing the columns of some parts of the matrix.
the lo
colSums()/rowSums() will be *much* faster and you can specify na.rm = TRUE.
-roger
Jonathan Baron wrote:
On 06/14/03 20:51, Jean Eid wrote:
Dear R users,
I am looking for a more efficient way to compute the sum of columns of a
matrix.
I am currently using apply(data, 2, sum) however, I am bui
Dear Jean and Jonathan,
colSums() should be more efficient, but (unless I misunderstand the size of
the problem) a problem this small shouldn't take a half hour. On my ageing
800 MHz, 512MB Windows 2000 PC, the result was essentially instantaneous
either way, though an order of magnitude faster
On 06/14/03 20:51, Jean Eid wrote:
>Dear R users,
>I am looking for a more efficient way to compute the sum of columns of a
>matrix.
>I am currently using apply(data, 2, sum) however, I am building a data set
>from another one by summing the columns of some parts of the matrix.
>the loop is taking
Dear R users,
I am looking for a more efficient way to compute the sum of columns of a
matrix.
I am currently using apply(data, 2, sum) however, I am building a data set
from another one by summing the columns of some parts of the matrix.
the loop is taking too long (about 1/2 hour) for a 4462 * 20
