如何使用ggplot2绘制填充轮廓图？

Question

I have some data and I have tried a filled.contour plot which seems nice. However, the legend is hard to control, so I am thinking to use ggplo2 . But I have no clue how to plot a filled.contour using ggplot2 .

The data contains 840 rows (which stand for the dates), and 12 columns (which stand for 12 time scales). Here is an example

set.seed(66)
Mydata <- sample(x=(-3:3),size = 840*12,replace = T)
Mydata <- matrix(data=Mydata,nrow=840,ncol=12)
Dates <- seq(from=1948+1/24, to= 2018,by=1/12)
data.breaks <- c(-3.5,-2.5,-1.5,0,1.5,2.5,3.5)
filled.contour(Dates,seq(1:12),Mydata,col=cols(11),xlab="",ylab="time-scale",levels=data.breaks)

As we can see, the legend intervals are not what I want. I want to show -3.5,-2.5,-1.5,0,1.5,2.5,3.5 on the legend and I believe it is much easier to do this with ggplot2 . Thanks for any help.

Answer 1

A ggplot2 alternative to filled.contour is stat_contour .

library(ggplot2)
library(reshape2)
set.seed(66)
Mydata <- sample(x=(-3:3),size = 840*12,replace = T)
Mydata <- matrix(data=Mydata,nrow=840,ncol=12)
Dates <- seq(from=1948+1/24, to= 2018,by=1/12)
data.breaks <- c(-3.5,-2.5,-1.5,0,1.5,2.5,3.5)
rownames(Mydata) <- Dates

d <- melt(Mydata)
colfunc = colorRampPalette(c("brown", "red", "yellow", "white"))
ggplot(d, aes(Var1, Var2, z=value, fill = value)) +
     stat_contour(geom="polygon", aes(fill=..level..)) +
     scale_fill_gradientn(colours = colfunc(7), breaks=data.breaks, limits=c(-4,4),
                          values=scales::rescale(data.breaks))+
     theme_bw() + 
     scale_x_continuous(name="", breaks=seq(1950,2010,20), expand=c(0,0)) + 
     scale_y_continuous(name="time-scale", expand=c(0,0))+
     guides(fill = guide_colorbar(barwidth = 2, barheight = 15))