Blog Archives

Including arguments in R CMD BATCH mode

August 16, 2007
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When you have multiple computers or processors at your disposal and wish to run the same script with different arguments, use the following at the command line (here described for Linux; remove the linebreak, it is just there for display purposes):$ R CMD BATCH --no-save --no-restore '--args a=1 b=c(2,5,6)'test.R test.out & Where test.R is the R script file you wish...

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Variance-Covariance Matrix in glm

July 20, 2007
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This is a small function Venables and Ripley provide in their MASS book. You don't need it anymore because vcov() has a method for the glm class. However, it is useful to see how to extract bits from a fitted model object.vcov.glm #return the variance-covariance matrix of a glm object #from p. 188 in Venables and Ripley....

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Visualizing Data

July 18, 2007
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Sometimes it is helpful to see the plots created from the example files within R libraries. Of course you can paste them directly into R, but this web page allows you to view the images within the context of the help files:R Graphical ManualsAlso, chec...

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Repeat elements of a vector

May 17, 2007
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Two methods. The first produces a vector, the second a one column matrix.x=1:10# Method 1rep(x,each=3)# Method 2matrix(t(matrix(x,length(x),3)))

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Convert image to matrix in R

May 17, 2007
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This is how to use the Pixmap library to read in an image as a matrix.> library(pixmap)# the next command may only work on Linux> system("convert foo.tiff foo.ppm")> img To get info on your new object: > str(img)Although included in the previous output, the size of the image can be extracted by:>img@sizeThen to extract the red channel...

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Calculate turning angles and step lengths from location data

May 16, 2007
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anglefun <- function(xx,yy,bearing=TRUE,as.deg=FALSE){ ## calculates the compass bearing of the line between two points ## xx and yy are the differences in x and y coordinates between two points ## Options: ## bearing = FALSE returns +/- pi inst...

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