Displaying 20 results from an estimated 20000 matches similar to: "matrix manipulation with its rows"
2011 Aug 02
1
My R code is not efficient
Dear R users,
I have two n*1 integer vectors, y1 and y2, where n is very very large.
I'd like to compute
elbp = 4^(y1) * 5^(y2) * sum_{i=0}^{max(y1, y2)} [{ (y1-i)! * (i)! *
(y2-i)! }^(-1)];
that is, I need to compute "elbp" for each (y1, y2) pair.
So I made R code like below, but I don't think it's efficient
Would you plz tell me how to avoid this "for"
2011 Aug 08
3
on "do.call" function
Dear all,
Even though one of R users answered my question, I cannot understand, so I
re-ask this question.
I am trying to use "do.call", but I don't think I totally understand this
function.
Here is an simple example.
--------------------------------------------
> B <- matrix(c(.5,.1,.2,.3),2,2)
> B
[,1] [,2]
[1,] 0.5 0.2
[2,] 0.1 0.3
> x <- c(.1,.2)
>
2013 Jan 17
2
create block diagonal with each rows
Dear R users,
I'd like to create a block diagonal matrix with each rows in a matrix.
Here is a simple example. (In fact, the matrix is big)
x <- matrix(1:20, 4,5)
> x
[,1] [,2] [,3] [,4] [,5]
[1,] 1 5 9 13 17
[2,] 2 6 10 14 18
[3,] 3 7 11 15 19
[4,] 4 8 12 16 20
With each rows in matrix x, I'd like to make the matrix below.
2008 Apr 21
3
means and variances of several groups in the matrix
Dear R users,
I have 32 observations in data x. After sorting this, I want to compute
means and variances of 3 groups divided by "nr".
Actually, the number of groups is flexible. Any suggestion will be greatly
appreciated.
Kathryn Lord
---------------------------------------------------------------------------
x=rnorm(32)
y=sort(x)
nr=matrix(c(12,11,10,10,10,11),2,3)
> nr
2011 Aug 13
3
optimization problems
Dear R users
I am trying to use OPTIMX(OPTIM) for nonlinear optimization.
There is no error in my code but the results are so weird (see below).
When I ran via OPTIM, the results are that
Initial values are that theta0 = 0.6 1.6 0.6 1.6 0.7. (In fact true vales
are 0.5,1.0,0.8,1.2, 0.6.)
--------------------------------------------------------------------------------------------
>
2011 Nov 02
4
array manipulation
Hello,
I'm at the very beginning of the learning process of this language.
Sorry in advance for the (possible but plausible) stupidity of my question.
I would like to find a way to permute the DIMENSIONS of an array.
Something that sounds like the function "permute()" in matlab.
Given an array C of dimensions c x d x T , for instance, the command
permute(C, [2 1 3])
would provide
2010 May 24
2
Table to matrix
Dear R users,
I am trying to make this (3 by 10) matrix A
--A----------------------------------------------------
0 0 0 0 1 0 0 0 0 0
0 0 0 0 0 1 0 0 0 0
0 0.5 0.5 0 0 0 0 0 0 0
-------------------------------------------------------
from "mass.func"
--mass.func-------------------------------------------
> mass.func
$`00`
prop
5
1
$`10`
2008 Oct 08
3
Re move repeated values
Dear R users,
I'd like to make this data
rem.y = c(-1,0,2,4,5)
from
y = c(-1,-1,0,2,2,2,2,4,4,5,5,5,5,5).
That is, I need to remove repeated values.
Here is my code, but I don't think it is efficient. How could I improve
this?
#------------------------------------------------------------------------
y = c(-1,-1,0,2,2,2,2,4,4,5,5,5,5,5)
n=length(y)
for (i in 1:n) #
2009 Jul 28
3
character vector -> numeric matrix ??
Dear R users...
I'd like to change this character vector, "zz",
zz <- c("12","56","89")
to the following numeric matrix.
[,1] [,2]
[1,] 1 2
[2,] 5 6
[3,] 8 9
Actually, "zz" vector has a long length.
Any comments will be greatly appreciated.
Kathryn Lord
--
View this message in context:
2010 Apr 16
3
VERY SIMPLE QUESTION
Dear R users,
I am looking for more efficient way to compute the followings
--------------------------------------------------------------------------
a <- matrix(c(1,1,1,1,2,2,2,2),4,2)
b <- matrix(c(1,2,3,4),4,1)
Eventually, I want to get this matrix, `c`.
c <- matrix(c(1/1,1/2,1/3,1/4,2/1,2/2,2/3,2/4),4,2)
--------------------------------------------------------------------------
2012 Dec 25
2
for loop not working
dear R family,i have a matrix of 444 columns. what i want to do is the following.
1. starting from column 1 i want to select every 37th column on the way. more precisely i want to select column 1, 38,75,112,149 and so on.
2.starting from column 2, i again want to select every 37th column. which means 2,39,76,113,150 and so on.
similarly starting from 3 till 37th column.
i have tried following loop
2011 Aug 11
5
generate two sets of random numbers that are correlated
Dear R users
I'd like to generate two sets of random numbers with a fixed correlation
coefficient, say .4, using R.
Any suggestion will be greatly appreciated.
Regards,
Kathryn Lord
--
View this message in context: http://r.789695.n4.nabble.com/generate-two-sets-of-random-numbers-that-are-correlated-tp3735695p3735695.html
Sent from the R help mailing list archive at Nabble.com.
2010 Mar 29
2
Need help on matrix manipulation
Dear all,
Ket say I have 3 matrices :
mat1 <- matrix(rnorm(16), 4)
mat2 <- matrix(rnorm(16), 4)
mat3 <- matrix(rnorm(16), 4)
Now I want to merge those three matrices to a single one with dimension
4*3=12 and 4 wherein
on resulting matrix, row 1,4,7,10 will be row-1,2,3,4 of "mat1", row
2,5,8,11 will be row-1,2,3,4 of "mat2" and row 3,6,8,12 will be row-1,2,3,4
of
2009 Jul 27
2
Splitting matrix into several small matrices
Dear R users...
I need to split this matrix(or dataframe), for example,
z <- matrix(c(13,1,1,1,1,12,0,0,0,0,8,1,0,1,1,8,0,1,0,0,
10,1,1,1,1,3,0,1,0,0,3,1,0,1,1,6,1,1,1,1),8,5,byrow = T)
> z
[,1] [,2] [,3] [,4] [,5]
[1,] 13 1 1 1 1
[2,] 12 0 0 0 0
[3,] 8 1 0 1 1
[4,] 9 0 1 0 0
[5,] 10 1 1 1 1
2008 Nov 15
1
make a triple summation more efficient
Dear R users...
I made the R-code for this triple summation computation
http://www.nabble.com/file/p20517134/a.jpg
-------------------------------------------------
Here is my code..
x=seq(.1,1,.1); l=10
y=seq(1,10); m=10
z=seq(.1,1,.1); n=10
sum(sapply(1:l, function(i) {sum(sapply(1:m, function(j) {sum(sapply(1:n,
function(k){exp(x[i]*y[j]*z[k] )/gamma(y[j]+1)}))^(1.5) }))}))
2008 Nov 17
2
re sults from "do.call" function
Dear R users...
I made this by help of one of R users.
_________________________________________________________________
X=matrix(seq(1,4), 2 , 2)
B=matrix(c(0.6,1.0,2.5,1.5) , 2 , 2)
func <- function(i,y0,j) { y0*exp(X[i,]%*%B[,j]) }
list1 <- expand.grid( i=c(1,2) , y0=c(1,2) , j=c(1,2) )
results <- do.call( func , list1 )
2011 Aug 29
3
gradient function in OPTIMX
Dear R users
When I use OPTIM with BFGS, I've got a significant result without an error
message. However, when I use OPTIMX with BFGS( or spg), I've got the
following an error message.
----------------------------------------------------------------------------------------------------
> optimx(par=theta0, fn=obj.fy, gr=gr.fy, method="BFGS",
>
2013 Feb 28
2
Fortune?
I think the rule is that you can do anything as long as you don't
complain. If you want to complain, you must follow the instructions.
-- Jari Oksanen in
Re: [Rd] Keeping up to date with R-devel
--
Patrick Burns
pburns at pburns.seanet.com
twitter: @burnsstat @portfolioprobe
http://www.portfolioprobe.com/blog
http://www.burns-stat.com
(home of:
'Impatient R'
'The R
2008 Mar 23
2
scaling problems in "optim"
Dear R users,
I am trying to figure out the control parameter in "optim," especially,
"fnscale" and "parscale."
In the R docu.,
------------------------------------------------------
fnscale
An overall scaling to be applied to the value of fn and gr during
optimization. If negative, turns the problem into a maximization problem.
Optimization is performed on
2013 Apr 09
2
Behaviors of diag() with character vector in R 3.0.0
Dear all,
According to CHANGES IN R 3.0.0:
o diag() as used to generate a diagonal matrix has been re-written
in C for speed and less memory usage. It now forces the result
to be numeric in the case diag(x) since it is said to have 'zero
off-diagonal entries'.
diag(x) does not work for character vector in R 3.0.0 any more. For example,
v <- c("a",