search for: btsai00

Hi all, I'm interested in doing a dot plot where *both* the size and color (more specifically, shade of grey) change with the associated value. I've found examples online for ggplot2 where you can scale the size of the dot with a value: http://had.co.nz/ggplot2/graphics/6a053f23cf5bdfe5155ab53d345a5e0b.png Or scale the color with the value:

Hi all, I'm trying to figure out the effective differences between BFGS and L-BFGS-B are, besides the obvious that L-BFGS-B should be using a lot less memory, and the user can provide box constraints. 1) Why would you ever want to use BFGS, if L-BFGS-B does the same thing but use less memory? 2) If i'm optimizing with respect to a variable x that must be non-negative, a common approach

Hi, I am trying to use the glmnet package to do some simple feature selection. However, I would ideally like to be able to specify the number of features to return (the glmnet package, as far as I can tell, only allows specification of a regularization parameter, lambda, that in turn returns a model with a specific number of non-zero features). Is there a straightforward way of calculating the

Hi, I'm having problems using the 'width' aesthetic attribute for the geom_errorbarh. This is the same problem reported earlier here, but I'll try to write the problem more clearly: http://www.mail-archive.com/r-help@r-project.org/msg62371.html The problem I'm having is that, the 'width' attribute is supposed to set the height of the endpoints of the whiskers, and

hi all, i have a file of the following format that i want to read into a matrix: 010101001110101 101010010111110 010010100100000 ... it has no headers or row names. I tried to use read.table(), but it doesn't allow me to specify nothing as the column separator (specifying sep='' means whitespace for that function). read.fwf doesn't seem appropriate either. [[alternative HTML

Hi all, I'm relatively new to using R, and have been trying to fit an L1 regularization path using coxpath from the glmpath library. I'm interested in using a cross validation framework, where I crossvalidate on a training set to select the lambda that achieves the lowest error, then use that value of lambda on the entire training set, before applying to a test set. This seems to entail

hi, I'm looking for a package to compare two hazard ratios (and assign statistical significance) obtained from two different predictive models. I know of the hr.comp2 function from the survcomp package, but was wondering if there's any other packages out there. thanks! [[alternative HTML version deleted]]

hi, I'm looking to compare two area under ROC values for different classifiers on the same data -- is there an r function to do this? Thanks! [[alternative HTML version deleted]]

Hi, I was wondering if anyone has implemented a numerically stable function to compute log(sum(exp(x))) ? Thanks! Brian [[alternative HTML version deleted]]

Hi, i was looking into the documentation for the rma() function in affy() package, and was trying to figure out how exactly the background normalization is done. I read all three papers cited in the rma() documentation, but the most detailed explanation i could find was in Irizary et al., 2003, where they state that they compute B(PM_{ijn}) = E[s_{ijn} | PM_{ijn}] where s_{ijn} is assumed to

Hi, I am trying to do multinomial regression using the glmnet package, but the following gives me an error (for no reason apparent to me): library(glmnet) cv.glmnet(x=matrix(c(1,2,3,4,5,6,1,2,3,4,5,6), nrow=6),y=as.factor(c(1,2,1,2,3,3)),family='multinomial',alpha=0.5, nfolds=2) The error i get is: Error in if (outlist$msg != "Unknown error") return(outlist) : argument is of

Hi, I'm interested in building a Cox PH model for survival modeling, using 2 covariates (x1 and x2). x1 represents a 'baseline' covariate, whereas x2 represents a 'new' covariate, and my goal is to figure out where x2 adds significant predictive information over x1. Ideally, I could get a p-value for doing this. Originally, I thought of doing some kind of likelihood ratio