Displaying 20 results from an estimated 10000 matches similar to: "Symmetric matrix"
2011 Jul 23
1
Achieving 'reverse-Vech' of a matrix
Let say i have a square matrix and applied the 'vech' operator to stack the lower triangular elements into a vector:
> Mat <- matrix(1:25, 5)
> Mat
? ? ?[,1] [,2] [,3] [,4] [,5]
[1,] ? ?1 ? ?6 ? 11 ? 16 ? 21
[2,] ? ?2 ? ?7 ? 12 ? 17 ? 22
[3,] ? ?3 ? ?8 ? 13 ? 18 ? 23
[4,] ? ?4 ? ?9 ? 14 ? 19 ? 24
[5,] ? ?5 ? 10 ? 15 ? 20 ? 25
> Mat[lower.tri(Mat)]
?[1] ?2 ?3 ?4 ?5 ?8 ?9 10 14
2008 Sep 17
5
Loop on vector name
[My previous message rejected, therefore I am sending same one with some modification]
I have 3 vectors with object name : dat1, dat2, dat3
Now I want to create a loop, like :
for (i in 1:3)
{
cat(sd(dati))
}
How I can do this in R?
Regards,
2008 Oct 11
5
Extracting subset of a vector
I have 2 vecros :
x<-c(100,96,88,100,100,96,80,68,92,96,88,92,68,84,84,88,72,88,72,88)
x1 = sample(x, 5, replace=FALSE)
Now i want to get remaining values of vector "x" those are not member of vector "x1". Can anyone please tell me how to do that?
2008 Mar 15
1
Fwd: Re: How to create following chart for visualizing multivariate time series
Thanks David, It is working. Holtman's also gave me a solution but, I wanted to have a color pallet for description of colors, that was not in his solution.
However I need one small modification. If I want to plot only lower diagonal elements of 'dat' then how should I proceed? What I want is, to visualize only lower diagonal elements and having the color pallet on them only. Also
2008 Mar 15
1
How to create following chart for visualizing multivariate time series
Let me take an artifical matrix :
dat = matrix(rnorm(200*200), 200, 200)
My goal is to visualize this matrix according to the procedure, described in previous mails. I took Mendelssohn's advice and got following advice :
?plot.im
Z <- setcov(owin())
plot(Z) .................... etc
However I can not reproduce this example in my problem. How I can change my data
2007 Jun 12
3
Panel data
Dear all R users,
I have a small doubt about panel data analysis. My basic understanding on Panel data is a type of data that is collected over time and subjects. Vector Autoregressive Model (VAR) model used on this type of data. Therefore can I say that, one of statistical tools used for analysis of panel data is VAR model? If you clarify my doubt I will be very grateful.
Thanks and regards,
2010 Oct 15
7
Problem with merging two zoo objects
Dear all, I have following 2 zoo objects. However when I try to merge those 2 objects into one, nothing is coming as intended. Please see below the objects as well as the merged object:
> dat11
V2 V3 V4 V5
2010-10-15 13:43:54 73.8 73.8 73.8 73.8
2010-10-15 13:44:15 73.8 73.8 73.8 73.8
2010-10-15 13:45:51 73.8 73.8 73.8 73.8
2010-10-15 13:46:21 73.8 73.8 73.8 73.8
2008 Sep 10
2
Woring message in as.yearmon()
I have following dataset:
> res
[,1] [,2] [,3]
[1,] 1946 4 1.27
[2,] 1946 5 1.27
[3,] 1946 6 1.27
[4,] 1946 7 1.27
[5,] 1946 8 1.52
[6,] 1946 9 1.52
[7,] 1946 10 1.52
[8,] 1946 11 1.52
[9,] 1946 12 1.62
[10,] 1947 1 1.62
[11,] 1947 2 1.62
[12,] 1947 3 1.62
[13,] 1947 4 1.87
[14,] 1947 5 1.87
[15,] 1947 6 1.87
Now I write following code
2008 Sep 10
3
How to find where is the <space> in data
I have following
" 1975 01 7711.16"
Here I need to identify where the <space> is there and then concatenate rest of the digits without <space>, i.e. I want to have "1975017711.16". Is there any R function?
Regards,
2008 Sep 09
4
Compiling date
Hi,
I have following kind of dataset (all are dates) in my Excel sheet.
09/08/08
09/05/08
09/04/08
09/02/08
09/01/08
29/08/2008
28/08/2008
27/08/2008
26/08/2008
25/08/2008
22/08/2008
21/08/2008
20/08/2008
18/08/2008
14/08/2008
13/08/2008
08/12/08
08/11/08
08/08/08
08/07/08
However I want to use R to compile those data to make all dates in same format. Can anyone please tell me any automated way
2008 Feb 29
1
Fwd: Re: How to create following chart for visualizing multivariate time series
I used ?image function to do that, like below :
require(grDevices) # for colours
x <- y <- seq(-4*pi, 4*pi, len=27)
r <- sqrt(outer(x^2, y^2, "+"))
image(x, y, r, col=gray((0:32)/32))
However my next problem to add a color pallet for color description [as shown in following link]. If anyone here tell me how to do that, it will be good for me.
Regards,
Megh Dal
2007 May 04
2
Analysis for Binary time series
hi,
hi, good morning everyone. I have a time series with binary outputs like : 0001011110100.................etc. Now I want to forecast the future values of that. Can anyone please tell me whether there is any tools exist in literature for dealing with this kind of binary observation? If possible please provide me some good references in net as well.
rgd,
Megh
2010 Jul 13
3
Need help on index for time series object
Dear all,
Please forgive me if there is a duplicate post; my previous mail perhaps didnt reach the list.......
Let say I have following time series
library(zoo)
> dat1 <- zooreg(rnorm(10), start=as.Date("2010-01-01"), frequency=1)
> dat1[c(3, 7,8)] = NA
> dat1
2010-01-01 2010-01-02 2010-01-03 2010-01-04 2010-01-05 2010-01-06 2010-01-07 2010-01-08 2010-01-09
2008 Oct 02
3
Adding plane in a 3D scatterplot
I have drawn a 3D scatter plot :
library(mnormt)
library(scatterplot3d)
dat = cbind(rmnorm(3, rep(0,2), diag(2)), 1:3)
scatterplot3d(dat)
Now I want to do 2 things :
1 : In the Z-axis (i.e. height), I want to see only numbers 1,2,3, etc NOT, 1,1.5,2,2.5.............
2. I want to add two Horizontal planes at hight z=2 and z=3. Those two planes should look like "bottom" of that 3D plot
2011 Jan 25
2
Downloading data from internet
Dear all, I need to download an excel file from net, on which I have address
like http://www.2shared.com/file/MMSMWv4B/MyData.html. Can I somehow
directly download this file into my R workbook?
Thanks,
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2011 Feb 13
3
String manipulation
Please consider following string:
MyString <- "ABCFR34564IJVEOJC3434"
Here you see that, there are 4 groups in above string. 1st and 3rd groups
are for english letters and 2nd and 4th for numeric. Given a string, how can
I separate out those 4 groups?
Thanks for your time
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2010 Jun 02
3
Seeking help on Vectorize()
Dear falks, here I have written following function :
fn <- Vectorize(function(x = 1:3, y = 3:6) {
x <- matrix(x, nrow=1)
y <- matrix(y, ncol=1)
dat <- apply(x, 2, function(xx) {
apply(y, 1, function(yy) {
return(xx + yy) } ) })
return(dat)}, SIMPLIFY = TRUE)
If I run this function, I got
2006 Nov 18
3
Random sample from log-normal distribution
Dear all R users,
Please forgive me if my question is too trivial.
Suppose I have two variables, (x,y) which is
log-normally distributed with expected value (mu1,
mu2) and some variance-covariance matrix. Now I want
to draw a random sample of size 1000 from this
distribution. Is there any function available to do
this?
Thanks and regards,
Megh
2008 May 07
2
Solution of function
Hi,
I want to find solution of function : f(x,y) = x'Cx - a under constraints :
0 < x,y < p
0 < x-y< q
where a, p,q are given constants and x = (x, y) and C is a 2X2 matrix (given)
Can anyone suggest me any R function to do that?
---------------------------------
[[elided Yahoo spam]]
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2011 Dec 23
1
Help creating a symmetric matrix?
Hi,
I am trying to work with the output of the MINE analysis routine found at
http://www.exploredata.net
Specifically, I am trying to read the results into a matrix (ideally an
n x n x 6 matrix, but I'll settle right now for getting one column into
a matrix.)
The problem I have is not knowing how to take what amounts to being one
half of a symmetric matrix - excluding the diagonal -