Colour Schemes for Scientific Data Visualization

An implementation of Paul Tol's colour schemes for use with 'graphics' or 'ggplot2'. These schemes are ready for each type of data (qualitative, diverging or sequential), with colours that are distinct for all people, including colour-blind readers. This package provides tools to simulate colour-blindness and to test how well the colours of any palette are identifiable. Several scientific thematic schemes (geologic timescale, land cover, FAO soils, etc.) are also implemented.

Overview

khroma is a utility package: it provides usefull colour schemes for archaeological data visualization. khroma provides Paul Tol's colour schemes and several thematic palettes (geologic timescale, FAO Soil Reference Groups, etc.) with scales for ggplot2.

Installation

Install the released version of khroma from CRAN:

install.packages("khroma")

Or install the development version from GitHub with:

devtools::install_github("nfrerebeau/khroma")

Usage

Paul Tol's Colour Schemes

Paul Tol offers carefully chosen schemes, ready for each type of data, with colours that are:

• distinct for all people, including colour-blind readers;
• distinct from black and white;
• distinct on screen and paper;
• matching well together.

All the scales presented in his 2018 technical note [1] are implemented here, for use with graphics or ggplot2.

Qualitative data

Diverging data

Sequential data

Scientific colour schemes

The following scientific colour schemes are available:

• International Chronostratigraphic Chart
• FAO Soil Reference Groups

More will be added in future releases (suggestions are welcome).

[1] Tol, Paul (2018). Colour Schemes. SRON. Technical Note No. SRON/EPS/TN/09-002. URL: https://personal.sron.nl/~pault/data/colourschemes.pdf.