similar to: Quantile Regression Packages

Hi, I was recently plowing through the docs of the quantreg package by Roger Koenker and came across the total variation penalty approach to 1-dimensional spline fitting. I googled around a bit and have found some papers originated in the image processing community, but (apart from Roger's papers) no paper that would discuss its statistical aspects. I have a couple of questions in this

I'm in the very initial stage of expanding the formula processing in my quantile regression function rq() to handle additive nonparametric components, say qss(x), or qss(x,z). I need some advice about strategy for formula processing. My initial foray was to use: terms(formula,specials="qss") and then modify the components of the resulting terms.object. But in changing formula

Recursively walk the formula performing the replacement: g <- function(e, ...) { if (length(e) > 1) { if (identical(e[[2]], as.name(names(list(...))))) { e <- eval(e, list(...)) } if (length(e) > 1) for (i in 1:length(e)) e[[i]] <- Recall(e[[i]], ...) } e } g(f, lambdas = 2:3) ## y ~ qss(x, lambda = 2L) + qss(z, 3L) + s On Fri, Oct

Suppose I have a formula like this: f <- y ~ qss(x, lambda = lambdas[1]) + qss(z, lambdas[2]) + s I?d like a function, g(lambdas, f) that would take g(c(2,3), f) and produce the new formula: y ~ qss(x, lambda = 2) + qss(z, 3) + s For only two qss terms I have been using g <- function(lambdas, f){ F <- deparse(f) F <- gsub("lambdas\\[1\\]",lambdas[1],F) F

Hi I am trying to install the package "pheno", but it needs the package "nprq" by Roger Koenker et al. which I can I find this package? It does not seem to be on CRAN and googling also doesn't give me an URL - is it still somewhere available? Thanks, Rainer -- NEW EMAIL ADDRESS AND ADDRESS: Rainer.Krug at uct.ac.za RKrug at sun.ac.za WILL BE DISCONTINUED END OF

Hi, Let me pick up this old thread. How does one extract the locations of the knots (ends of the segments) from the fit object below? Thanks, Vadim >From : roger koenker < roger_at_ysidro.econ.uiuc.edu > Date : Tue 31 May 2005 - 10:23:19 EST It is conventional to fit piecewise linear models by assuming Gaussian error and using least squares methods, but one can argue that

Dear Friends, Here is an algorithm for finding concave hulls: http://get.dsi.uminho.pt/local/ Has anyone implemented such an algorithm in R? RSiteSearch('concave hull') didn't reveal one (I think). _____________________________ Professor Michael Kubovy University of Virginia Department of Psychology Postal Address: P.O.Box 400400, Charlottesville, VA 22904-4400 Express Parcels

I'm having difficulty with an environmental issue: I have an additive model fitting function with a typical call that looks like this: require(quantreg) n <- 100 x <- runif(n,0,10) y <- sin(x) + rnorm(n)/5 d <- data.frame(x,y) lam <- 2 f <- rqss(y ~ qss(x, lambda = lam), data = d) this is fine when invoked as is; x and y are found in d, and lam is found the

I am modeling a trend surface using trmat and want to trim the resulting matrix to the area enclosed by my real data (i.e., remove all the extrapolated areas). I was using chull and in.chull to calculate the convex hull and change all the other values created by trmat to NA. However, my real data has portions that are slightly concave so chull would give me slivers that are extrapolations from

Dear Peter. I guess you know that Jim Lindseys code include nordr and ordglm in library gnlm - I attach the htmls which do various linear and nonlinear ordinal regressions - exemplified with just the data mentioned, McCullagh (1980) JRSS B42, 109-142. I had it work very fine. -----Oprindelig meddelelse----- Fra: Peter Malewski <p.malewski at tu-bs.de> Til: Troels Ring <tring at

I'm having difficulty with Rprof. I have a documentation example test.qss that runs fine without profiling, but under Rprof, > Rprof() > source("test.qss") Error in standardGeneric("model.matrix") : UseMethod used in an inappropriate fashion Luke wrote about a similar circumstance last summer: # From: Luke Tierney (luke@stat.umn.edu) # Date: Fri Jul

Hello list, I would add: # dovecot Startup script for the dovecot server # # chkconfig: - # processname: dovecot # config: /path/to/config # pidfile: /path/to/pid So that it supports the chkconfig used by RHEL and clones too. Also, maybe it should be installed by the Makefile's install target? it could then also set: DAEMON=/path/to/dovecot/daemon instead of:

Since the number of responses to my query was large, Roger has asked me to summarise the information. The summary is listed below Thanks to all the people who bothered to help me out: Alan Mead <adm@ipat.com> Beattie, Jay <JBeattie@accdir.com> Bruce Elrick <bruce.elrick@saltus.ab.ca> Christian Hammers <ch@lathspell.westend.com> David J. M. Karlsen

Dear friends, Do you know how to calculate the CONCAVE hull of a set of points (2- dimensional or n-dimensional)? is that possible in R? (With a "smoothing" parameter of course). Best, -- Corrado Topi Global Climate Change & Biodiversity Indicators Area 18,Department of Biology University of York, York, YO10 5YW, UK Phone: + 44 (0) 1904 328645, E-mail: ct529 at york.ac.uk

I'm trying to resolve a problem of Namespaces and probably have misunderstood something basic. In my quantreg package the function crq() has as its first argument a formula that typically contains something like this: Surv(y, ...) ~ foo, where Surv is a function from the survival package which quantreg suggests. When this syntax is encountered in ordinary usage Surv is resolved, I believe,

Hello, i have the following data: x=c(0,0.02,0.03,0.04,0.05,0.06,0.07,0.08,0.09,0.1,0.11,0.12,0.13,0.14,0.15,0.16,0.17,0.18,0.19,0.2,0.21,0.22,0.23,0.25,0.26,0.27,0.46,0.47,0.48,0.49) y=c(0.48,0.46,0.41,0.36,0.32,0.35,0.48,0.47,0.55,0.56,0.54,0.67,0.61,0.60,0.54,0.51,0.45,0.42,0.44,0.46,0.41,0.43,0.43,0.48,0.48,0.47,0.39,0.37,0.32,0.29) and tried to get piecewise linear regression. Doing a

Hi, I have used package quantreg to estimate a non-linear fit to the lowest part of my data points. It works great, by the way. But I'd like to extract the predicted values. The help for predict.qss1 indicates this: predict.qss1(object, newdata, ...) and states that newdata is a data frame describing the observations at which prediction is to be made. I used the same technique I used

Hi Arun, thank-you very much! The 2nd option worked perfectly. That was what I wanted. Now, I have another question. I am using the R packages dataRetrieval and EGRET from https://github.com/USGS-CIDA/WRTDS. I have 2 objects Daily and Sample that have the naming convention (Names = "21NC02WQ.C1000000" or whatevver the list of site names happens to be) that I need to have after running

Hi: Is there any function in R to fit ordinal regression models (linear and non-linear) described by Peter McCullagh. Regression Models for Ordinal Data, JRSS-B, 1980, 42:109-142 Thanks, Venkat ----------------------------------------------------------------------- E. S. Venkatraman, Ph.D. Phone: (212) 639-8520 Fax: (212) 717-3137 Assistant Attending Member Memorial

I fit a proportional odds model with the polr-function of the MASS package from Venables and Ripley Applying the confint method to calculate confidence intervals for the parameters I get the following error message Waiting for profiling to be done... Re-fitting to get Hessian Error in X[, -i, drop = FALSE] : incorrect number of dimensions Can someone explain the error-message? (The