March 2009

Multiple plot in a single image using ImageMagick

March 31, 2009 | Paolo

Sometimes you need to add several plots/images either by row or by column to a single page/sheet.If you generate all your plot with R base graphics you can easily accomplished the task using the par() function, e.g., using par(mfrow=c(2,2)) and then dr...
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How accurate or reliable are R calculations?

March 28, 2009 | markheckmann

On the REvolutions Blog there is a nice posting treating the often raised concern on “How good or reliable R is”. At my university R is hardly used. Sometimes I was asked by lecturers wether the calculations done by R and its packages are accurate. The linked posting treats this ... [Read more...]

Comparison of different circle graphs

March 24, 2009 | Cloud Wei

See in my Picasa here and get corrplot package here. Thanks Bob O'Hara's advice:)I found people's tastes differ, so input parameter col (fill color) and bg (background color) was added in new edition. What is more, now you can order your variables usin... [Read more...]

India Census 2001 – Part 1

March 22, 2009 | anandram

I was trying – for the last few weeks – to get the 2001 Indian census data. Alas the census website is under construction. But fortunately the Internet rewind button works! Thankfully the literacy data was online there. The raw data is available here. I cleaned up the data so that it is ... [Read more...]

Dianne Reeves at Dominican

March 16, 2009 | Thinking inside the box

Yesterday afternoon, we had another chance to see Dianne Reeves (wikipedia). This time, it almost felt like she came to us as she was headlining at the annual trustee benefit concert at Dominican University, a small college about a mile from our place. And as in 2007 and 2003, she did not ... [Read more...]

Identify Data Points in Off-Screen R Graphics Devices

March 16, 2009 | Yihui Xie

Today Ruya Gokhan Kocer asked me how to use the R function identify() in off-screen graphics devices. Actually it’s pretty easy as long as we obtain the list returned by identify(pos = TRUE). For example, # open a windows device x11() x = rnorm(20) y = rnorm(20) plot(x, y) # identify 5 points ... [Read more...]

Color: The Cinderella of dataviz

March 13, 2009 | mike

“Avoiding catastrophe becomes the first principle in bringing color to information: Above all, do no harm.”  — Envisioning Information, Edward Tufte, Graphics Press, 1990    Color is one of the most abused and neglected tools in data visualization. It is abused when we make poor color choices; it is neglected when we rely ... [Read more...]

Visulization of correlation matrix

March 12, 2009 | Cloud Wei

Color Imagedata(mtcars)fit = lm(mpg ~ ., mtcars)cor = summary(fit, correlation = TRUE)$correlationcor2 = t(cor[11:1, ])colors = c("#A50F15", "#DE2D26", "#FB6A4A", "#FCAE91", "#FEE5D9","white", "#EFF3FF", "#BDD7E7", "#6BAED6", "#3182BD", "#08519C")image(1:11, 1:11, cor2, axes = FALSE, ann = F, col = colors)text(rep(1:11, 11), rep(1:11, each = 11), round(100 * cor2))Ellipseslibrary(... [Read more...]

no “Infinities”

March 12, 2009 | Paolo

Thanks to  Pierre-Yves for the below useful tip!if you have a dataset from which you want the max or min but they have to be real number and not "Inf" or "-Inf" there is a way to do it:data
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