Gradient of n colors ranging from color 1 and color 2

Question

I often work with ggplot2 that makes gradients nice  click here for an example    I have a need to work in base and I think scales can be used there to create color gradients as well but I m severely off the mark on how   The basic goal is generate a palette of n colors that ranges from x color to y color   The solution needs to work in base though   This was a starting point but there s no place to input an n      scale colour gradientn colours c  red    blue      I am well aware of   brewer pal 8   Spectral      from RColorBrewer   I m looking more for the approach similar to how ggplot2 handles gradients that says I have these two colors and I want 15 colors along the way   How can I do that

User · Answer

Try the following   color gradient  lt - function x  colors c  red   yellow   green    colsteps 100      return  colorRampPalette colors   colsteps    findInterval x  seq min x  max x   length out colsteps         x  lt - c  1 100  2   100 1  2  plot x col color gradient x   pch 19 cex 2

User · Answer

The above answer is useful but in graphs  it is difficult to distinguish between darker gradients of black  One alternative I found is to use gradients of gray colors as follows   palette gray colors 10  0 9  0 4   plot rep 1 10  col 1 10 pch 19 cex 3     More info on gray scale here    Added   When I used the code above for different colours like blue and black  the gradients were not that clear   heat colors   seems more useful    This document has more detailed information and options  pdf

User · Answer

Just to expand on the previous answer colorRampPalettecan handle more than two colors   So for a more expanded  heat map  type look you can      colfunc lt -colorRampPalette c  red   yellow   springgreen   royalblue    plot rep 1 50  col  colfunc 50    pch 19 cex 2      The resulting image

User · Answer

colorRampPalette could be your friend here   colfunc  lt - colorRampPalette c  black    white    colfunc 10     1    000000    1C1C1C    383838    555555    717171    8D8D8D    AAAAAA     8    C6C6C6    E2E2E2    FFFFFF    And just to show it works   plot rep 1 10  col colfunc 10  pch 19 cex 3

[r] Gradient of n colors ranging from color 1 and color 2

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