nice ggplot intro tutorial. Just run the commands, about 6 pages = flexible 1-3 hours of learning, depending how much reading you want to pair it with

by Ramon Saccilotto

• Top-left is not Tufte-compliant because primary colours occupy too much of the space (it’s distracting).
• Top-left also uses colours that do not grade across our perceptual space. (Although hues do grade across wavelengths of light smoothly, we don’t perceive it that way.)
• Topographical maps that use green, brown, and yellow likewise do not grade across perceptive colour space appropriately.
• Top-right is fine but perhaps a little bland. A topographical map with a lot of hills and valleys would benefit more from this than one trying to show finer detail. (My intended application—overlaying two elliptical single-peaked utility functions—would have a hard time with such an approach.)

@hadley recommended this paper to me. I was asking how to select colours to represent level curves (isoclines / isoutility curves / etc) on a 2-D plot. (I.e., how to plot a ²→ℝ¹ function effectively with colours other than greyscale+red.)

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Big-money quote from Zeileis, Hornik, and Murrell:

It has been hypothesised that human vision evolved in three stages:

1. perception of light/dark contrasts;
2. yellow/blue contrasts (usually associated with our notion of warm/cold);
3. green/red contrasts (helpful for assessing the ripeness of fruit).

….. The subjective experience of [colour, however,] is less well understood.

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• RGB (old news)
• HSV (old news)
• CIELUV
• HCL = Hue Chroma Lightness

hi-res

My interpretation of [Leland Wilkinson’s] grammar [of statistical graphics]:

Data is the most important thing, and the thing that you bring to the table.

—Geometric objects … what you actually see on the plot: points, lines, polygons, etc.

Statistics transform the data in many useful ways. For example, binning and counting to create a histogram….

—Scales map values in the data space to values in an aesthetic space, whether it be colour, or size, or shape. Scales also provide an inverse mapping: a legend.

—A coordinate system describes how data coordinates are mapped to the plane of the graphic. It also provides axes and gridlines to make it possible to read the graph.

— A facetting, or conditioning, specification…. to reproduce the same plot for different subsets of the data. The facetting specification describes those subsets and how the facets should be arranged in to a plot.