similar to: Converting variance covariance matrix to correlation matrix

Dear All, I am wondering if there is an R function to convert a covariance matrix to a correlation matrix. I have a covariance matrix sigma and I want to compute the corresponding correlation matrix R from sigma. Thank you very much, Bernard --------------------------------- [[alternative HTML version deleted]]

List members, Via searches I've seen similar discussion of this topic but have not seen resolution of the particular issue I am experiencing. If my search on this topic failed, I apologize for the redundancy. I am attempting to generate random covariance matrices but would like the corresponding correlations to be uniformly distributed between -1 and 1. The approach I have been using is:

There is a R function to calculate weighted mean : weighted.mean() under stats package. Is there any direct R function for calculating weighted variance as well? [[alternative HTML version deleted]]

Dear r-users, Suppose I have two data sets data set-1 Date height ------------------------ 1/11/2005 10 2/11/2005 23 3/11/2005 54 4/11/2005 21 5/11/2005 22 data set-2 weight -------- 32 45 11 Now I want to combine this two data sets. i.e. i want to see: Date height weight ------------------------------------------- 3/11/2005 54

All, I have a repeated measures data frame and was wondering if the covariance matrix can be calculated via some created indexing or built-in R function. Specifically, say there are 3 variables, where potassium concentration is measured 6 times on each patient. Patient number (discrete) Time (1 to 6, discrete) Potassium (continuous variable) I want the covariance/correlation matrix for the

Dear all R users, I want to insert the R logo in every graphic that I made in my Statistical analysis using R. Can anyone tell me whether is it possible or not and if possible how to do this? your help will be highly appreciated. Thanks and Regards, Arun [[alternative HTML version deleted]]

Dear aDVISOR, Hope I am not disturbing you. Can you tell me how I can perform Multivariate Garch analysis in R. Also please, it is my humble request let me know some resource materials on Multivariate Garch analysis itself. Sincerely yours, -- Arun Kumar Saha, M.Sc.[C.U.] S T A T I S T I C I A N [Analyst] Transgraph Consulting [www.transgraph.com] Hyderabad, INDIA Contact # Home:

Dear all, I have a variable 'x' like that: > x [1] "2005-09-01" Here, 2005 represents year, 09 month and 01 day. Now I want to create three variables naming: y, m, and d such that: y = 2005 m = 09 d = 01 can anyone tell me how to do that? Regards, [[alternative HTML version deleted]]

Hi all, I wrote some user defined function for my own. Now I want to get a mechanism so that every time I start R, those function will automatically be loaded in R without manually copying pasting. Can gurus here pls tell me how to do that? Or I have to build my own packages bundled with those functions. However I am not familiar in writing R package yet. Regards, [[alternative HTML version

Dear all R users, I am wondering whether there is any way to replace all "NA" values in a data frame by some numerical value, suppose 1000? Thanks and Regards [[alternative HTML version deleted]]

Hi all, I am wondering how to write a 'list' object to a file. I already gone through some threads like http://mail.python.org/pipermail/python-list/2001-April/080639.html, however could not trace out any reliable solution. I tried following : > write.table(calc, file="c:/data.csv") Error in data.frame("200501" = c(-0.000387071806652095, -0.000387221689252648, :

Dear all, It is not a R related problem rather than statistical/mathematical. However I am posting this query hoping that anyone can help me on this matter. My problem is to get the Geometrical Interpretation of Eigen value and Eigen vector of any square matrix. Can anyone give me a light on it? Thanks and regards, Arun [[alternative HTML version deleted]]

Dear all R-users, I would like to draw a tangent of a given function for a particular (given) point. However the straight line representing it should not cut any axis, it should be a small line. Can anyone tell me how to do this? Thanks, Arun [[alternative HTML version deleted]]

Dear R users, Suppose I have a 4*5 data frame like this: Date x1 x2 x3 x4 1/1/2004 100 22 12 34 2/1/2004 33 -22 33 12 3/1/2004 12 12 -11 5 4/1/2004 1 223 22 1 Now I want to get a correlation matrix for this dataset excluding column-1 and column-3 i.e. I want to get a correlation matrix for variables

Here I am in a simulation study where I want to find different values of x and y such that f(x,y)=c (some known constant) w.r.t. x, y >0, y<=x and x<=c1 (another known constant). Can anyone please tell me how to do it efficiently in R. One way I thought that I will draw different random numbers from uniform dist according to that constraints and pick those which satisfy f(x,y)=c. However

Dear all R users, Can anyone tell me how I can get estimate of SE of coefficients from, lm() function? I tried following : x = 1:10 lm(x[-1]~x[-10]-1)$coefficients Here I got the est. of coefficient, however I also want to get some "automated" way to get estimate of SE. Regards, [[alternative HTML version deleted]]

Dear all r-users, Suppose I have two data frame: A 1 3 4 5 2 and B 5 6 3 5 Now I want combine this two data frames without losing any value from either data frame. More precisely I want to see A B 1 5 3 6 4 3 5 5 2 NA I tried with cbind function but failed, as it only works when two data frames have equal number of rows. Can anyone suggest me any code that can be used for any

Dear r-users, suppose I have n normal distributions with parameter N(0,i) i=1,2,.......,n respectively. Now I want to generate 500 random number for each distribution. And want to put all 500*n random numbers in a single data frame. I tried with following code: >n=20 random = data.frame(n) for ( i in 2: length) { random[,i] = random(500,mean=0,sd=i) } but while executing this I

Dear all R gurus, My question is related to statistics rather directly to R. Suppose (X,Y) has a bivariate normal distrubution. I want to find two values of X and Y say x, and y respectively, such that: P[X<x, Y<y] = 0.05 My questions are : 1. Can x and y be uniquely found? 2. If it is, how I can find them using R Your help will be highly appreciated. Thanks and regards,

There is "if-else" loop if I have to choose 1 item from a 2-item list. However if I have a list of 4 items (let say) then how i can choose a single item without employing 'if-else' loop? I mean in VBA I can use "select-case", is there any equivalent in R as well? Regards, [[alternative HTML version deleted]]