[R] Gradient plots in ggplot2

[PIKAL Petr]

Hi Phillip.

You could try some transformations of your data. Either directly in
scale_fill_gradient or in original data. log transition would be OK but not
with negative data. You could play with some transitions from scales
package. I think that you could also use rescaler function, but I do not
know how.

ggplot(df,aes(x=a,y=c,fill=b))+
   geom_tile()+
   geom_text(label=paste0(round(b,1),"%"),
     size=10,colour="gold")+
   scale_fill_gradient(low="red",high="blue",na.value="grey50", trans="log")

Cheers.
Petr

> -----Original Message-----
> From: R-help <r-help-bounces using r-project.org> On Behalf Of
> phil using philipsmith.ca
> Sent: Tuesday, March 9, 2021 5:06 AM
> To: r-help using r-project.org
> Subject: [R] Gradient plots in ggplot2
> 
> I am having trouble with a gradient fill application in ggplot2, caused
> by outlier values. In my reprex, most of the values are between 2 and
> -2, but there are two outliers, 10 and -15. The outliers stand out well,
> which is good, but all the other numbers show almost no colour
> variation. I would like to continue with bold colours for the outliers,
> while having a more variable gradient, perhaps but not necessarily in a
> different colour, for the values between 2 nd -2. Any ideas on how this
> can be done?
> 
> 
> library(ggplot2)
> a <- c(rep(1,6),rep(2,6),rep(3,6),rep(4,6))
> b <- c(0.1, 0.5,-0.3, 1.2,-0.4,-1.2,
>         0.7, 0.8,-1.2,-0.5,10.0, 0.3,
>         0.2,-0.4,-15.,-0.4,-0.9,  NA,
>         0.1, 1.3,-1.4, 0.5,-0.5, 0.1)
> c <- c(rep(c("a","b","c","d","e","f"),4))
> df <- data.frame(a,b)
> ggplot(df,aes(x=a,y=c,fill=b))+
>    geom_tile()+
>    geom_text(label=paste0(round(b,1),"%"),
>      size=10,colour="gold")+
>    scale_fill_gradient(low="red",high="blue",na.value="grey50")
> 
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