similar to: Variance of a single number

Displaying 20 results from an estimated 3000 matches similar to: "Variance of a single number"

2003 Mar 17
4
X11 connection error in web cgi mode only
Dear all, I am trying to create a web interface using Perl-CGI to call R plots and to display them. The following codes works perfectly fine when I copy and paste into the console directly or if I save it into script.file and then R --no-save < script.file producing the graphs. jpeg("graph.jpeg", width=400, height=400) plot(rnorm(100)) dev.off() Now, I put the line system("R
2005 Mar 02
5
Differences between package and library terminology
Just out of curiosity, what is the difference between the terms for package and library ? Why are we loading a package with the library() command ? If this is a case of RTFM, I would be happy to do so if pointed in the right direction. I have searched the FAQ and mail archives and only came up with http://tolstoy.newcastle.edu.au/R/help/05/02/12162.html but this still does not explain what is
2004 Oct 01
3
same test statistic for t-test with and without equal variance assumption
Could some kindly tell me if I am supposed to be getting the same test statistic value with var.equal=TRUE and var.equal=FALSE in t.test ? set.seed(1066) x1 <- rnorm(50) x2 <- rnorm(50) t.test(x1, x2, var.equal=FALSE)$statistic # 0.5989774 t.test(x1, x2, var.equal=TRUE)$statistic # 0.5989774 ??? Here are my own calculations that shows that perhaps the result when var.equal=TRUE is
2003 Jun 07
3
Error Compiling e1071
Dear all, I am trying to compile the package e1071 (version 1.3-11) with R CMD INSTALL. I tried with R 1.7.0 on Redhat Linux 2.4.7-10 and R 1.6.2 on Linux 2.4.9-34smp but keep getting the same error message during configure : WARNING: g++ 2.96 cannot reliably be used with this package. Please use a different compiler. Can anyone help me with this or at least point me in the right direction ?
2005 Jul 25
5
passing formula arguments cv.glm
I am trying to write a wrapper for the last example in help(cv.glm) that deals with leave-one-out-cross-validation (LOOCV) for a logistic model. This wrapper will be used as part of a bigger program. Here is my wrapper funtion : logistic.LOOCV.err <- function( formu=NULL, data=NULL ){ cost.fn <- function(cl, pred) mean( abs(cl-pred) > 0.5 ) glmfit <- glm(
2003 Apr 24
1
Invalid font in bitmap()
Dear all, A few weeks ago I asked about X11() availability using CGI-perl. The general advice was to use bitmap which requires ghostscript (Xvnc and Xvbf were the other alternatives). My system administrator got around to installing Aladin Ghostscript 6.0 and the setting the R_GSCMD environment variable. Other system specification is given below. But now I have a new problem that says that font
2004 Nov 04
2
list files ignoring the case option
Sorry if this is a question more on regular expressions. I am dealing with several files which have been badly named. For example the files are given either the extensions txt, TXT or Txt. I wish to select all those files ending with 'txt' ignoring case. Here is how I would do it in bash (Redhat FC2) : touch a1.txt a2.TXT a3.Txt txt.control TXT.control ls -1 | grep -i
2004 Sep 13
2
calculating memory usage
I am comparing two different algorithms in terms of speed and memory usage. I can calculate the processing time with proc.time() as follows but am not sure how to calculate the memory usage. ptm <- proc.time() x <- rnorm(1000000) proc.time() - ptm I would like to be within R itself since I will test the algorithm several hundred times and in batch mode. So manually looking up
2005 Feb 25
2
display full form in args
Forgive me for I do not fully comprehend the idea of classes and methods but I was wondering if someone could help explain why the function args () behaves the way it does. Why does args(cut) show the simplified version instead of the more complete one as in help("cut"). This is true for few other functions (e.g. plot, rep). > args(cut) function (x, ...) Sometime I can get
2008 Sep 11
9
How to load functions in R
Hello, I am trying to use self created functions in other scripts than the one where they are stored. For the moment I am using the following structure of commands to do that: 1. Load the text file with the functions in the current script: x=parse("path") 2. transform the tex in a function: f1=eval(x[1]), f2=eval(x[2]) if more than one function is stored in the text file 3. use the
2005 Nov 09
5
How to find statistics like that.
Hi there, Suppose mu is constant, and error is normally distributed with mean 0 and fixed variance s. I need to find a statistics that: Y_i = mu + beta1* I1_i beta2*I2_i + beta3*I1_i*I2_i + +error, where I_i is 1 Y_i is from group A, and 0 if Y_i is from group B. It is large when beta1=beta2=0 It is small when beta1 and/or beta2 is not equal to 0 How can I find it by R? Thank you very much
2005 Nov 06
3
How can I assign an argument to transfer whether by ref or by value?
Hello guys, I am wondering the default way of transferring arguments in R. Is it by value or by ref in default case, or could that be changed explicitly? Cheers, Xiaofan --- Xiaofan Li Department of Applied Mathematics and Theoretical Physics University of Cambridge
2002 Jul 26
5
Is there a function for finding local extrema.
I have a vector with about 100.000 values representing a quite regular function (sinusoid like). I would like to find all local maxima of this function (should be about 4000). Is there a native routine for R? Thanks in advance Eryk. -- _|_ \|/ \|/ Eryk Witold Wolski tel :0049-(0)30-8413-1543 w w ?v? 'v? \'v'/ MPI Moleculare Genetik fax :0049-(0)30-8413-1139 |
2005 Aug 15
2
stepAIC invalid scope argument
I am trying to replicate the first example from stepAIC from the MASS package with my own dataset but am running into error. If someone can point where I have gone wrong, I would appreciate it very much. Here is an example : set.seed(1) df <- data.frame( x1=rnorm(1000), x2=rnorm(1000), x3=rnorm(1000) ) df$y <- 0.5*df$x1 + rnorm(1000, mean=8, sd=0.5) # pairs(df); head(df) lo <-
2002 Jul 15
2
meaning of error message about collinearity
You are using a method that needs to estimate the covariance matrix of all the variables. If you have 80 variables, there are (80+1)*80/2 = 3240 variances and covariances to estimate. How many data points do you think you need to do that? Some people assume the covariance matrix is diagonal (i.e., assuming all the variables are uncorrelated). Even then you still have 80 variances to estimate.
2007 Jul 24
7
Obtaining summary of frequencies of value occurrences for a variable in a multivariate dataset.
Hi all, If the question below as been answered before I apologize for the posting. I would like to get the frequencies of occurrence of all values in a given variable in a multivariate dataset. In short for each variable (or field) a summary of values contained with in a value:frequency pair, there can be many such pairs for a given variable. I would like to do the same for several such variables.
2008 Aug 24
1
howto optimize operations between pairs of rows in a single matrix like cor and pairs
Hi, I calculating the output of a function when applied to pairs of row from a single matrix or dataframe similar to how cor() and pairs() work. This is the code that I have been using: pairwise.apply <- function(x, FUN, ...){ n <- nrow(x) r <- rownames(x) output <- matrix(NA, nc=n, nr=n, dimnames=list(r, r)) for(i in 1:n){ for(j
2002 Sep 02
1
Coplot graph size manipulation
I am currently plotting a graph with the function coplot() conditional on two factors which gives me 36 sub-panels. I have a few questions in general about changing the size of the graph. My question follows : a) I have a fair bit of text to put on the margin sides using mtext(). What is the best way to shrink the whole graph to say 80 - 90% so that I can include a bit more words. b) Since I am
2008 Oct 02
1
back transforming output from negative binomial
Dear all, I used the glm.nb with the default values from the MASS package to run a negative binomial regression. Here is a simple example: set.seed(123) y <- c( rep(0, 30), rpois(70, lambda=2) ) smoke <- factor( sample( c("NO", "YES"), 100, replace=T ) ) height <- c( rnorm(30, mean=100, sd=20), rnorm(70, mean=150, sd=20) ) fit <- glm.nb( y
2005 Jul 18
5
colnames
Hi, I have a matrix with column names starting with a character in [0-9]. After some matrix operations (e.g. copy to another matrix), R seems to add a character 'X' in front of the column name. Is this a normal default behaviour of R? Why has it got this behaviour? Can it be changed? What would be the side effect? Thank you. Regards, Gilbert [[alternative HTML version deleted]]