Displaying 20 results from an estimated 800 matches similar to: "A function for raising a matrix to a power?"
2006 Sep 21
2
Exponentiate a matrix
Suppose I have a square matrix P
P <- matrix(c(.3,.7, .7, .3), ncol=2)
I know that
> P * P
Returns the element by element product, whereas
> P%*%P
Returns the matrix product.
Now, P^2 also returns the element by element product. But, is there a
slick way to write
P %*% P %*% P
Obviously, P^3 does not return the result I expect.
Thanks,
Harold
[[alternative HTML version
2006 Nov 23
1
Partial derivatives of a matrix with respect to a single element
UseRs,
We are using projection matrices in demographic analyses, and one
technique is to calculate partial derivatives of a matrix with respect
to a variable appearing in one or more of its elements. For example,
consider the matrix A:
| a*b a*c |
| d d |
If I'm not mistaken, the partial derivative of matrix A w/ respect to
variable 'a' is the matrix:
| b c |
| 0 0
2006 Aug 16
5
How to remove similar successive objects from a vector?
Is there some (much) more efficient way to do this?
VECTOR=c(3,2,4,5,5,3,3,5,1,6,6);
NEWVECTOR=VECTOR[1];
for(i in 1:(length(VECTOR)-1))
{
if((identical(VECTOR[i], VECTOR[i+1]))==FALSE){
NEWVECTOR=c(NEWVECTOR,VECTOR[i+1])}
}
> VECTOR
[1] 3 2 4 5 5 3 3 5 1 6 6
> NEWVECTOR
[1] 3 2 4 5 3 5 1 6
_______________________________
Atte Tenkanen
University of Turku, Finland
2006 Jun 19
3
Border line width?
Is there some way to change the line widths of plot borders?
I couldn't find any parameters for that purpose.
Atte Tenkanen
University of Turku, Finland
2012 Dec 17
3
How to test whether is.element() returns only TRUE's
Hi,
How can I test, whether all the values that is.element() -function returns are TRUE's
Eg.
> (is.element(c(1,4,2),c(1,2,3)))
[1] TRUE FALSE TRUE
This doesn't work:
> (is.element(c(1,4,2),c(1,2,3)))==TRUE
[1] TRUE FALSE TRUE
Best,
Atte Tenkanen, FT, MuM
http://users.utu.fi/attenka/
2006 Oct 06
4
Row comparisons to a new matrix?
Hi,
Can somebody tell me, which is the fastest way to make comparisons between all rows in a matrix (here A) and put the results to the new symmetric matrix? I have here used cosine distance as an example, but the comparison function can be any other, euclidean dist etc.
A=rbind(c(2,3),c(4,5),c(-1,2),c(5,6))
M=matrix(nrow=length(A[,1]),ncol=length(A[,1]))
for(i in 1:length(A[,1]))
{
for(j in
2016 Apr 16
5
Mean of hexadecimal numbers
Hi,
How would you calculate the "mean colour" of several colours, for
example c("#FF7C00","#00BF40","#FFFF00")?
Yours,
Atte Tenkanen
2016 Apr 27
3
Same sum, different sets of integers
Hi,
Do you have ideas, how to find all those different combinations of
integers (>0) that produce as a sum, a certain integer.
i.e.: if that sum is
3, the possibilities are c(1,1,1), c(1,2), c(2,1)
4, the possibilities are
c(1,1,1,1),c(1,1,2),c(1,2,1),c(2,1,1),c(2,2),c(1,3),c(3,1)
etc.
Best regards,
Atte Tenkanen
2006 Mar 18
2
How to divide too long labels?
Is there any possibility to divide too long text in a plot to two or more
lines, when using labels-parameter in the text()-command?
Here is an example picture:
http://users.utu.fi/attenka/253.jpeg
My example script is something like this:
text(1,0.7,labels=Chordnames[fnid(pcs%%12)]) # according to Larry
Solomon's table http://solomonsmusic.net/pcsets.htm
Chordnames is a long vector with
2016 Apr 16
2
Mean of hexadecimal numbers
... and if you need to convert back: ?as.hexmode
-- Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Sat, Apr 16, 2016 at 8:20 AM, Bert Gunter <bgunter.4567 at gmail.com> wrote:
> ?strtoi
>
> You'll have to remove
2007 Jul 12
2
is.null doesn't work
Hi,
What's wrong here?:
> v=c(`-`,`+`,1,`^`,`^`,NA,NA,"X",9,"X",2)
> i2=16
> v[i2]
[[1]]
NULL
> is.null(v[i2])
[1] FALSE
Is it a bug or have I misunderstood something?
Atte Tenkanen
University of Turku, Finland
2016 Apr 16
0
Mean of hexadecimal numbers
On 16/04/2016 8:47 AM, Atte Tenkanen wrote:
> Hi,
>
> How would you calculate the "mean colour" of several colours, for
> example c("#FF7C00","#00BF40","#FFFF00")?
>
Bert answered your subject line question. Your text is asking something
else: if those are colours, you don't want to treat each of them as a
single integer.
A
2006 Nov 19
4
The most common row in a matrix?
Hi,
How do you get the most common row from a matrix? If I have a matrix
like this
array(1:3,dim=c(4,5))
[,1] [,2] [,3] [,4] [,5]
[1,] 1 2 3 1 2
[2,] 2 3 1 2 3
[3,] 3 1 2 3 1
[4,] 1 2 3 1 2
in which rows 1 and 4 are similar, I want to find that vector c
(1,2,3,1,2).
Atte Tenkanen
University of Turku, Finland
2017 Aug 04
2
Layer problem in DrawDensity3D (VecStatGraphs3D)
Hi,
When plotting the density estimation with DrawDensity3D-function (in
package VecStatGraphs3D) it often happens that the end product ie.
layers are not intact , see figure in the link:
https://www.dropbox.com/s/vzyaiu0vso8hjw2/20623868_10213333234554853_1371245353_n.png?dl=0
Can we somehow effect on that an get intact layers?
--
Atte Tenkanen
2008 Feb 01
2
Saving a big table or matrix
Dear R-users,
How do you save a big table or matrix as an independent object and attach it to your Rdata-project when needed?
Atte Tenkanen
University of Turku, Finland
Department of Musicology
+023335278
2010 Apr 16
3
Is it ok to apply the z.test this way?
Dear R-users,
I want to check if certain values are from random distribution, that includes values between 0-1. So, it is not really normal even though shapiro.test says it is highly normal... Can I do something like this and think that the values given are right. z.test is from package TeachingDemos.
-------------------------------------------------------------------------------
2006 Aug 22
4
Successive subsets from a vector?
I'd like to pick every imbricated five character long subsets from a
vector. I guess there is some efficient way to do this without loops...
Here is a for-loop-version and a model for output:
VECTOR=c(1,4,2,6,5,0,11,10,4,3,6,8,6);
ADDRESSES=c();
for(i in 1:(length(VECTOR)-4)){
ADDRESSES[i]=paste(VECTOR[i:(i+4)],collapse="")
}
> ADDRESSES
[1] "14265"
2007 Jul 15
2
Break during the recursion?
Hi,
Is it possible to break using if-condition during the recursive function?
Here is a function which almost works. It is for inorder-tree-walk.
iotw<-function(v,i,Stack,Indexes) # input: a vector and the first index (1), Stack=c(), Indexes=c().
{
print(Indexes)
# if (sum(i)==0) break # Doesn't work...
if (is.na(v[i])==FALSE & is.null(unlist(v[i]))==FALSE)
{Stack=c(i,Stack);
2006 Sep 08
8
Weighted association map
Could somebody program this kind of plot type to R, if none exists,
based on mds or correlation tables or some more suitable method? What
do you think about idea? Does it work? None similar or better exists?
http://weightedassociationmap.blogspot.com/
Atte Tenkanen
University of Turku, Finland
2016 Apr 16
0
Mean of hexadecimal numbers
?strtoi
You'll have to remove the "#" first, e.g. via substring()
-- Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Sat, Apr 16, 2016 at 5:47 AM, Atte Tenkanen <attenka at utu.fi> wrote:
> Hi,
>
> How