[R] apply a color range (kind of like a heat map) to the values in each cell of a data frame

Jim Lemon drj|m|emon @end|ng |rom gm@||@com
Fri Jun 18 05:29:15 CEST 2021

Hi Ding,
There are a number of "value to color" functions in various packages.
One is "color.scale" in the plotrix package:

s1 <-c(0.085,0.086,0.139,0.129,0.235,0.177,0.000,0.126,0.271,0.000,0.083,0.163)
s2 <-c(0.000,0.093,0.000,0.080,0.072,0.388,0.138,0.107,0.000,0.000,0.474,0.000)
s13 <-c(0.000,0.077,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.166,0.308,0.000)
s3 <-c(0.000,0.478,0.000,0.332,0.163,0.000,0.000,0.000,0.145,0.469,0.000,0.000)
test1 <-data.frame(s1,s2,s13,s3)
# generate a matrix of colors

color.scale calculates colors using linear interpolation of the values
in three color spaces (RGB, HSV or HCL). You may be interested in some
of the plotting functions in plotrix that employ color.scale,
particularly "size_n_color".


On Fri, Jun 18, 2021 at 10:04 AM Yuan Chun Ding <ycding using coh.org> wrote:
> Dear R users,
> I have a numeric table with 140 rows and 30 columns, here I only made partial table,  test1,  as an example.  I want to apply a blue color range to the value in each cell of  the data frame test1.
> I found some R code using DT library. However, I only can see the colored table at my R studio viewer window, also only show the first 10 rows.  I hope to save the colored table into a PNG file and want to modify the size of each cell, so I can apply the code to a much bigger table with 140 rows and 30 column.
> Can you help me?
> Thank you very much!!
> Ding
> s1 <-c(0.085,0.086,0.139,0.129,0.235,0.177,0.000,0.126,0.271,0.000,0.083,0.163)
> s2 <-c(0.000,0.093,0.000,0.080,0.072,0.388,0.138,0.107,0.000,0.000,0.474,0.000)
> s13 <-c(0.000,0.077,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.166,0.308,0.000)
> s3 <-c(0.000,0.478,0.000,0.332,0.163,0.000,0.000,0.000,0.145,0.469,0.000,0.000)
> test1 <-data.frame(s1,s2,s13,s3)
> row.names(test1)<c("COH_001","COH_002","COH_003","COH_004","COH_005","COH_006","COH_007","COH_008","COH_009","COH_010","COH_011","COH_012")
> library(DT)
> dtable1 <- datatable(test1, rownames=TRUE, options = list(lengthChange = FALSE, dom='t'))
> colRamp <- colorRamp(c("white","blue"))
> for(column in names(test1)){
>   x <- na.omit(test1[[column]])
>   brks <- quantile(x, probs = seq(.05, .95, .01))
>   RGB <- colRamp(c(0, (brks-min(x))/(max(x)-min(x))))
>   clrs <- apply(RGB, 1, function(rgb){
>     sprintf("rgb(%s)", toString(round(rgb,0)))
>   })
>   dtable1 <- dtable1 %>%
>     formatStyle(column, backgroundColor = styleInterval(brks, clrs))
> }
> dtable1
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