Thank you, that really worked. Actually received an even shorter version:
rowSums((t(apply(D > 0, 1, cumsum)) <= 3) * D)
2013/5/21 Xiao He
> Oops, a couple of missing brackets in the previous reply:
>
>
> foo<-function(x){
> temp=x[x>0]
> if(length(temp)>=3) sum(temp[1:3])
> else sum(te
That's a good one, Using cumsum + rowsum would definitely be faster,
On Tue, May 21, 2013 at 6:40 AM, José Verhoeven wrote:
> Thank you, that really worked. Actually received an even shorter version:
>
>
> rowSums((t(apply(D > 0, 1, cumsum)) <= 3) * D)
>
>
>
> 2013/5/21 Xiao He
>
>> Oops, a co
(split(mat3,row(mat3)),function(x) sum(x[x!=0][1:3],na.rm=TRUE))
# 1 2 3 4 5 6 7 8 9 10
# 5 0 12 8 5 14 6 10 10 8
A.K.
- Original Message -
From: José Verhoeven
To: r-help@r-project.org
Cc:
Sent: Tuesday, May 21, 2013 5:16 AM
Subject: [R] Sum first 3 non zero elements o
Oops, a couple of missing brackets in the previous reply:
foo<-function(x){
temp=x[x>0]
if(length(temp)>=3) sum(temp[1:3])
else sum(temp)
} #
Does this work? Probably not the fastest, but I think it does the job.
foo<-function(x){
temp=x[x>0]
if(length(temp)>=3) sum(temp[1:3])
else sum(temp)
set.seed(2)
mat<-matrix(sample(0:4, 25, replace=T, prob=c(1/2,rep(1/8,4)), ncol=5)
mat
# [,1] [,2] [,3] [,4] [,5]
#[1,]012
Hi there,
I've got this matrix D with, say 10 rows and 20 columns. For each row I want
to sum the first 3 non zero elements and put them in a vector z.
So if the first row D[1,] is
0 3 5 0 8 9 3 2 4 0
then I want z
z<-D[1,2]+D[1,3]+D[1,5]
But if there are less than 3 non zero elements, those sho
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