The Major Problem: Counts Need Transformation

If we are looking for more interesting differences among states, we should put them on a common footing, so that population size alone doesn’t dominate the effects. For disease, as an example, cases per hundred thousand is commonly used. Here’s what the GDP data looks like on that basis.

The Important Problem

The default continuous blue scale, even with transformed data, still requires squinting to distinguish different values.

Beyond Blue Palette Solutions

Viridis palette

Five bright (some might say garish) scales are available.

scale_fill_viridis_c(option="magma")

scale_fill_viridis_c(option="inferno")

scale_fill_viridis_c(option="plasma")

scale_fill_viridis_c(option="viridis")

scale_fill_viridis_c(option="viridis")

Fortunately, the palette can be muted with an alpha density filter

scale_fill_viridis_c(alpha = 0.50, option="cividis")

ggplot’s scale_fill_gradient can also over-ride default colors

The signature of scale_fill_gradient is

scale_fill_gradient(..., low = "#132B43", high = "#56B1F7", space = "Lab", na.value = "grey50", guide = "colourbar", aesthetics = "fill")

in the blue range. You can adjust that with the arguments to low and high. The following example uses #FBF7F6 and #A97263.

How did I come up with those particular values?

library(munsell)

show_col(seq_gradient_pal("white", mnsl("10R 4/6"))(x))(seq(0, 1, length.out = 25)))

This approach, and other do-it-yourself color palette selection approaches can become a time sink.See R color cheatsheet A better approach is to have a selection of pre-made color cards, and try them out until one of them highlights the differences you are trying to show.

RColorBrewer

This set of palettes plays well with ggplot and should answer most needs.

RColorBrewer

The three sections are for sequential (i.e., continuous), divergent (a neutral color in the center progressing toward more intense colors in both direction) or qualitative, for discrete data but coercible into continuous data.

Through ggplot’s scale_colour_distiller function, any of these can be smoothly interpolated into a six-interval scale.

All of the scales can be flipped, working from left-to-right on the palette or from right-to-left. Direction is indicated by direction = -1 or direction = 1.

Color abbreviations:

• Yl = Yellow
• Or = Orange
• Rd = Red
• Br = Brown
• Gn = Green
• Pu = Purple
• Bu = Blue

There are also:

• Reds
• Oranges
• Greys
• Greens
• Blues

The signature for scale_colour_distiller is

scale_fill_distiller(type = “seq”, palette = “YlOrRd”, direction = -1, labels = comma, guide = “colourbar”, aesthetics = “fill”)

Palette Snippets

Usage ggplot_map_object + [name of color scale]

    Alpha_default <- scale_alpha_continuous(range = c(0.1, 1))
  
    Alpha_75      <- scale_alpha_continuous(range = c(0.1, 0.75))
  
    Alpha_50      <- scale_alpha_continuous(range = c(0.1, 0.50))

    magma         <- scale_fill_viridis_c(option="magma")
  
    inferno       <- scale_fill_viridis_c(option="inferno")
  
    plasma        <- scale_fill_viridis_c(option="plasma")
  
    viridis       <- scale_fill_viridis_c(option="viridis")
  
    cividis       <- scale_fill_viridis_c(option="cividis")

    munsell_brown <- scale_fill_gradient(low = "#FBF7F6", high =  "#A97263", space = "Lab", na.value = "grey50", guide = "colourbar", aesthetics = "fill")

    # RColorBrewer

    BluesNeg1    <- scale_fill_distiller(type = "seq", palette = "Blues", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    BluesPos1    <- scale_fill_distiller(type = "seq", palette = "Blues", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    BuGnNeg1    <- scale_fill_distiller(type = "seq", palette = "BuGn", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    BuGnPos1    <- scale_fill_distiller(type = "seq", palette = "BuGn", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    BuPuNeg1    <- scale_fill_distiller(type = "seq", palette = "BuPu", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    BuPuPos1    <- scale_fill_distiller(type = "seq", palette = "BuPu", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    GnBuNeg1    <- scale_fill_distiller(type = "seq", palette = "GnBu", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    GnBuPos1    <- scale_fill_distiller(type = "seq", palette = "GnBu", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    GreensNeg1    <- scale_fill_distiller(type = "seq", palette = "Greens", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    GreensPos1    <- scale_fill_distiller(type = "seq", palette = "Greens", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    GreysNeg1    <- scale_fill_distiller(type = "seq", palette = "Greys", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    GreysPos1    <- scale_fill_distiller(type = "seq", palette = "Greys", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    OrangesNeg1    <- scale_fill_distiller(type = "seq", palette = "Oranges", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    OrangesPos1    <- scale_fill_distiller(type = "seq", palette = "Oranges", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    OrRdNeg1    <- scale_fill_distiller(type = "seq", palette = "OrRd", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    OrRdPos1    <- scale_fill_distiller(type = "seq", palette = "OrRd", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuBuGnNeg1    <- scale_fill_distiller(type = "seq", palette = "PuBuGn", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuBuGnPos1    <- scale_fill_distiller(type = "seq", palette = "PuBuGn", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuBuNeg1    <- scale_fill_distiller(type = "seq", palette = "PuBu", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuBuPos1    <- scale_fill_distiller(type = "seq", palette = "PuBu", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuRdNeg1    <- scale_fill_distiller(type = "seq", palette = "PuRd", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuRdPos1    <- scale_fill_distiller(type = "seq", palette = "PuRd", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PurplesNeg1    <- scale_fill_distiller(type = "seq", palette = "Purples", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PurplesPos1    <- scale_fill_distiller(type = "seq", palette = "Purples", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdPuNeg1    <- scale_fill_distiller(type = "seq", palette = "RdPu", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdPuPos1    <- scale_fill_distiller(type = "seq", palette = "RdPu", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RedsNeg1    <- scale_fill_distiller(type = "seq", palette = "Reds", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RedsPos1    <- scale_fill_distiller(type = "seq", palette = "Reds", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlGnBuNeg1    <- scale_fill_distiller(type = "seq", palette = "YlGnBu", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlGnBuPos1    <- scale_fill_distiller(type = "seq", palette = "YlGnBu", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlGnNeg1    <- scale_fill_distiller(type = "seq", palette = "YlGn", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlGnPos1    <- scale_fill_distiller(type = "seq", palette = "YlGn", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlOrBrNeg1    <- scale_fill_distiller(type = "seq", palette = "YlOrBr", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlOrBrPos1    <- scale_fill_distiller(type = "seq", palette = "YlOrBr", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlOrRdNeg1    <- scale_fill_distiller(type = "seq", palette = "YlOrRd", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    YlOrRdPos1    <- scale_fill_distiller(type = "seq", palette = "YlOrRd", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    BrBGNeg1    <- scale_fill_distiller(type = "seq", palette = "BrBG", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    BrBGPos1    <- scale_fill_distiller(type = "seq", palette = "BrBG", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PiYGNeg1    <- scale_fill_distiller(type = "seq", palette = "PiYG", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PiYGPos1    <- scale_fill_distiller(type = "seq", palette = "PiYG", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PRGnNeg1    <- scale_fill_distiller(type = "seq", palette = "PRGn", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PRGnPos1    <- scale_fill_distiller(type = "seq", palette = "PRGn", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuOrNeg1    <- scale_fill_distiller(type = "seq", palette = "PuOr", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PuOrPos1    <- scale_fill_distiller(type = "seq", palette = "PuOr", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdBuNeg1    <- scale_fill_distiller(type = "seq", palette = "RdBu", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdBuPos1    <- scale_fill_distiller(type = "seq", palette = "RdBu", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdGyNeg1    <- scale_fill_distiller(type = "seq", palette = "RdGy", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdGyPos1    <- scale_fill_distiller(type = "seq", palette = "RdGy", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdYlBuNeg1    <- scale_fill_distiller(type = "seq", palette = "RdYlBu", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdYlBuPos1    <- scale_fill_distiller(type = "seq", palette = "RdYlBu", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdYlGnNeg1    <- scale_fill_distiller(type = "seq", palette = "RdYlGn", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    RdYlGnPos1    <- scale_fill_distiller(type = "seq", palette = "RdYlGn", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    SpectralNeg1    <- scale_fill_distiller(type = "seq", palette = "Spectral", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    SpectralPos1    <- scale_fill_distiller(type = "seq", palette = "Spectral", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    AccentNeg1    <- scale_fill_distiller(type = "seq", palette = "Accent", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    AccentPos1    <- scale_fill_distiller(type = "seq", palette = "Accent", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Dark2Neg1    <- scale_fill_distiller(type = "seq", palette = "Dark2", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Dark2Pos1    <- scale_fill_distiller(type = "seq", palette = "Dark2", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PairedNeg1    <- scale_fill_distiller(type = "seq", palette = "Paired", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    PairedPos1    <- scale_fill_distiller(type = "seq", palette = "Paired", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Pastel1Neg1    <- scale_fill_distiller(type = "seq", palette = "Pastel1", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Pastel1Pos1    <- scale_fill_distiller(type = "seq", palette = "Pastel1", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Pastel2Neg1    <- scale_fill_distiller(type = "seq", palette = "Pastel2", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Pastel2Pos1    <- scale_fill_distiller(type = "seq", palette = "Pastel2", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Set1Neg1    <- scale_fill_distiller(type = "seq", palette = "Set1", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Set1Pos1    <- scale_fill_distiller(type = "seq", palette = "Set1", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Set2Neg1    <- scale_fill_distiller(type = "seq", palette = "Set2", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Set2Pos1    <- scale_fill_distiller(type = "seq", palette = "Set2", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Set3Neg1    <- scale_fill_distiller(type = "seq", palette = "Set3", direction = -1, labels = comma,  guide = "colourbar", aesthetics = "fill")

    Set3Pos1    <- scale_fill_distiller(type = "seq", palette = "Set3", direction = 1, labels = comma,  guide = "colourbar", aesthetics = "fill")

Credits

1. R Development Core Team (2008). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org.
2. Simon Urbanek and Jeffrey Horner (2015). Cairo: R graphics device using cairo graphics library for creating high-quality bitmap (PNG, JPEG, TIFF), vector (PDF, SVG, PostScript) and display (X11 and Win32) output. R package version 1.5-9. https://CRAN.R-project.org/package=Cairo
3. H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2016
4. Hao Zhu (2018). kableExtra: Construct Complex Table with ‘kable’ and Pipe Syntax. R package version 0.9.0. https://CRAN.R-project.org/package=kableExtra
5. Yihui Xie (2018). knitr: A General-Purpose Package for Dynamic Report Generation in R. R package version 1.20. Yihui Xie (2015) Dynamic Documents with R and knitr. 2nd edition. Chapman and Hall/CRC. ISBN 978-1498716963 Yihui Xie (2014) knitr: A Comprehensive Tool for Reproducible Research in R. In Victoria 6. Stodden, Friedrich Leisch and Roger D. Peng, editors, Implementing Reproducible Computational Research. Chapman and Hall/CRC. ISBN 978-1466561595
6. Charlotte Wickham (2018). munsell: Utilities for Using Munsell Colours. R package version 0.5.0. https://CRAN.R-project.org/package=munsell
7. Erich Neuwirth (2014). RColorBrewer: ColorBrewer Palettes. R package version 1.1-2. https://CRAN.R-project.org/package=RColorBrewer
8. Hadley Wickham (2018). scales: Scale Functions for Visualization. R package version 1.0.0.https://CRAN.R-project.org/package=scales
9. Pebesma, E., 2018. Simple Features for R: Standardized Support for Spatial Vector Data. The R Journal, https://journal.r-project.org/archive/2018/RJ-2018-009/
10. Kyle Walker (2018). tidycensus: Load US Census Boundary and Attribute Data as ‘tidyverse’ and22 ‘sf’-Ready Data Frames. R package version 0.8.1. https://CRAN.R-project.org/package=tidycensus
11. Hadley Wickham (2017). tidyverse: Easily Install and Load the ‘Tidyverse’. R package version 1.2.1. https://CRAN.R-project.org/package=tidyverse