R ggplot color bin widths appear unequal - r

Question

Hello I am ploting a graph which will have the legend,width of legend items not same can any one help me to resolve my problem
data file
< https://drive.google.com/file/d/1EKhRwup3vUC3KVFOOh4XtKERIr8FQj3x/view?usp=sharing>
code I have used
df=read.table("test.txt",sep='\t', header=TRUE)
df = data.frame(df)
nCol <- 15
myCol <- viridis(n = nCol)
myCol
ggplot(df, aes(log(data1), log(data2),color=data3),cex=1.9)+
geom_point() +
scale_colour_stepsn(colours = c(myCol),breaks = seq(0,100,by=10))+
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
panel.background = element_blank(), axis.line = element_line(colour = "black"))+
theme(text = element_text(size = 12, face="bold"),
legend.text = element_text(size = 7, face="bold"), legend.position="top",
legend.key.size = unit(10, "mm"),
legend.key.width=unit(10, "mm"))
at the end of legend 90-100 width is high compare to others

Answer 1

There are a couple of asides before addressing your main concern:
You can simplify your code by using scale_color_binned(type = "viridis"), which gives the same result as creating a vector of
viridis colors and interpolating them as you are doing, with the added advantage that you don't need to load the viridis library.
You can use log scales on the x and y axis without having to transform your
data, by using scale_x_log10() and scale_y_log10()
You can simplify your theme call by first calling theme_classic(), which gets rid of the need to specify all those element_blank() components.
For the specific problem that you encountered though, the reason for the appearance is that breaks are for the "internal" breaks of the binned scale. The outer edges of your scale are not breaks, but limits. By default, limits are not shown on binned scales, but you can turn them on using show.limits = TRUE after setting the limits to the desired value of c(0, 100)
So your above code can be rewritten as:
df <- read.table("test.txt", sep = "\t", header = TRUE)
ggplot(df, aes(log(data1), log(data2), color = data3), cex = 1.9) +
geom_point() +
scale_colour_binned(type = "viridis",
breaks = 1:9 * 10,
limits = c(0, 100),
show.limits = TRUE,
labels = function(x) round(x)) +
theme_classic() +
theme(text = element_text(size = 12, face = "bold"),
legend.text = element_text(size = 7, face = "bold"),
legend.position = "top",
legend.key.size = unit(10, "mm"))