Posts Tagged ‘ rstats ’

How to choose the right *apply function

October 13, 2012
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How to choose the right *apply function: This is an amazing stackoverflow answer to help you decide which of the many *apply functions (apply, lapply, sapply, vapply, mapply, rapply, tapply) is appropriate for the task at hand. I’m planning on doing...

Using cairographics with ggsave()

October 12, 2012
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Whenever possible, I try to save R graphic output in a vector format, typically pdf(). I also like to use the handy ggsave() function to do so, as it streamlines the process, and makes it easy to be consistent across formats. However, at times it is n...

From holey polygons to convex hulls

October 11, 2012
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I only rarely have the occasion to need the convex hull of a set of points, but I love chull(), so I’d like to share an example of how to use it. This Gist also offers a pretty straightforward application of the Split-Apply-Combine strategy (see...

Simple marimekko/mosaic plots

October 10, 2012
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I don’t really care for the name “marimekko” or “mosaic,” but I do like this type of plot as a means of illustrating proportions in nested categorical data, or as an alternative to the parallel time series plots discussed...

Conditional Colors and Shapes in plot() with ifelse()

October 9, 2012
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Here’s an example of how to color your plot shapes and pch using an ifelse() statement. Ifelse() is handy as it creates an easy way to branch a function. The syntax is: ifelse(logical.condition, option1, option2). Meaning, if the logical condi...

Functions for plotting and getting Greek in labels

October 8, 2012
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The problem: We often want to plot data and assign plot attributes based on characteristics of the data. For example, if we have a group of students with the following IQs, we might want to indicate who is an outlier in the statistical sense. I like...

Calculating distances (across matrices)

October 5, 2012
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This Gist is mostly for my future self, as a reminder of how to find distances between each row in two different matrices. To create a distance matrix from a single matrix, the function dist(), from the stats package is sufficient. There are times, ho...

its the Gramma an punctuashun wot its’ about, Rgiht?

October 4, 2012
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This is another of those confluence style posts, where a handful of things I’ve read in quick succession seem to phase lock in my mind: (brought to mind in part via @downes a week or so ago: How to Synch 32 Metronomes) The first was a post by Alan Levine on Making Text Work, which

Log odds ratios and an indicator matrix from categorical data

October 4, 2012
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A long title, but there are a couple of handy things in this Gist. The first, and more obscure, is the conversion of a data.frame of categorical variables into a matrix of dummy/binary/indicator variables, one for each category of each original variab...

Transforming a color scale

October 3, 2012
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In developing plots, I often use color (or “colour” in ggplot2 parlance) to reflect values of a third, non-X/Y, variable. Depending on the distribution of this Z variable, however, the effective color range can be narrow, making it difficul...