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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, etc.) with scales for ggplot2.


Install the released version of usethis from CRAN:


Or install the development version from GitHub with:

# install.packages("devtools")


Paul Tol’s Colour Schemes

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

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

Qualitative data

Diverging data

Sequential data

Scientific colour schemes

For now, the only scientific colour scheme available is that of the International Chronostratigraphic Chart. More will be added in future releases (suggestions are welcome).