Thanks to all. Great ideas. I found Eik Vettorazzi's suggesstion easy to
implrment:
ebarm<-vbarm<-NULL
...
if (is.null(ebarm)) ebarm<-ame.00$ei/k else ebarm<-ebarm+ame.00$ei/k
if (is.null(vbarm)) vbarm<-ame.00$vi/k else vbarm<-vbarm+ame.00$vi/k
...
Steven Yen
On 2/29/2024 10:31 PM, Ebert,Timothy Aaron wrote:
You could declare a matrix much larger than you intend to use. This works with
a few megabytes of data. It is not very efficient, so scaling up may become a
problem.
m22 <- matrix(NA, 1:600000, ncol=6)
It does not work to add a new column to the matrix, as in you get an error if
you try m22[ , 7] but convert to data frame and add a column
m23 <- data.frame(m22)
m23$x7 <- 12
The only penalty that I know of to having unused space in a matrix is the
amount of memory it takes. One side effect is that your program may have a
mistake that you would normally catch with a subscript out of bounds error but
with the extra space it now runs without errors.
Tim
-----Original Message-----
From: R-help <r-help-boun...@r-project.org> On Behalf Of Richard O'Keefe
Sent: Thursday, February 29, 2024 5:29 AM
To: Steven Yen <st...@ntu.edu.tw>
Cc: R-help Mailing List <r-help@r-project.org>
Subject: Re: [R] Initializing vector and matrices
[External Email]
x <- numeric(0)
for (...) {
x[length(x)+1] <- ...
}
works.
You can build a matrix by building a vector one element at a time this way, and
then reshaping it at the end. That only works if you don't need it to be a
matrix at all times.
Another approach is to build a list of rows. It's not a matrix, but a list of
rows can be a *ragged* matrix with rows of varying length.
On Wed, 28 Feb 2024 at 21:57, Steven Yen <st...@ntu.edu.tw> wrote:
Is there as way to initialize a vector (matrix) with an unknown length
(dimension)? NULL does not seem to work. The lines below work with a
vector of length 4 and a matrix of 4 x 4. What if I do not know
initially the length/dimension of the vector/matrix?
All I want is to add up (accumulate) the vector and matrix as I go
through the loop.
Or, are there other ways to accumulate such vectors and matrices?
> x<-rep(0,4) # this works but I like to leave the length open >
for (i in 1:3){
+ x1<-1:4
+ x<-x+x1
+ }
> x
[1] 3 6 9 12
> y = 0*matrix(1:16, nrow = 4, ncol = 4); # this works but I like to
leave the dimension open
[,1] [,2] [,3] [,4]
[1,] 0 0 0 0
[2,] 0 0 0 0
[3,] 0 0 0 0
[4,] 0 0 0 0
> for (i in 1:3){
+ y1<-matrix(17:32, nrow = 4, ncol = 4)
+ y<-y+y1
+ }
> y
[,1] [,2] [,3] [,4]
[1,] 51 63 75 87
[2,] 54 66 78 90
[3,] 57 69 81 93
[4,] 60 72 84 96
>
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat/
.ethz.ch%2Fmailman%2Flistinfo%2Fr-help&data=05%7C02%7Ctebert%40ufl.edu
%7Cdbccaccf29674b10b17308dc39114d38%7C0d4da0f84a314d76ace60a62331e1b84
%7C0%7C0%7C638447993707432549%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAw
MDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=
PtWjcDOnwO7PArVOSdgYbpz8ksjDPK%2Bn9ySyhwQC0gE%3D&reserved=0
PLEASE do read the posting guide
http://www.r/
-project.org%2Fposting-guide.html&data=05%7C02%7Ctebert%40ufl.edu%7Cdb
ccaccf29674b10b17308dc39114d38%7C0d4da0f84a314d76ace60a62331e1b84%7C0%
7C0%7C638447993707438911%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiL
CJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=Igb16
CBYgG21HLEDH4I4gfjjFBa3KjDFK8yEZUmBo8s%3D&reserved=0
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.r-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
