[R] Gradient plots in ggplot2

phii m@iii@g oii phiiipsmith@c@ phii m@iii@g oii phiiipsmith@c@
Tue Mar 9 16:36:42 CET 2021


Thank you for your suggestions. I found, after much experimentation, 
that scale_fill_gradientn did indeed provide a good solution, as below.

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=ifelse(is.na(b),"NA",paste0(round(b,1),"%")),
     size=10,colour="black")+
   scale_fill_gradientn(colours=c("yellow","green","red","lightblue"),
     values=c(0.0,0.5,0.7,1.0),na.value="white")

Philip


On 2021-03-08 23:44, Jeff Newmiller wrote:

> Perhaps scale_fill_gradientn() would be useful.
> 
> On March 8, 2021 8:05:52 PM PST, phil using philipsmith.ca wrote:
>> 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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