To cite package ‘colorRamp2’ in publications use:

  Gu Z (2022). _colorRamp2: Generate Color Mapping Functions_. R
  package version 0.0.1, <https://github.com/jokergoo/colorramp2>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {colorRamp2: Generate Color Mapping Functions},
    author = {Zuguang Gu},
    year = {2022},
    note = {R package version 0.0.1},
    url = {https://github.com/jokergoo/colorramp2},
  }