Image.plot in R not displaying the scalecale value at the edges of the color scale

Question

[

Note the difference in color scale in the two images. top image is the result from R 3.2.5, the same code creates the bottom image in R 2.15.2. I want to allow the "change" of labels in the upper graph, so that it matches the bottom. The sample code provided in this request was used to create both charts.

I am trying to build a map using image.plot, but the minimum and maximum colorscale values ​​do not display exactly on the hints. I ran into this problem in R version 3.2.5 (2016-04-14); Platform: x86_64-w64-mingw32 / x64 (64-bit version) and the library package fields "Spam version 1.4-0 (2016-08-29)

On the contrary, the same commands could correctly display the min and max values ​​at the edges of the color scale in R version 2.15.2 (2012-10-26), platform: x86_64-w64-mingw32 / x64 (64-bit) and "fields" 0.41- 0 (2014-02-26). Here is a sample code:

library(fields) temp <- matrix(data=rexp(200, rate=10), nrow=180, ncol=360) min(temp) max(temp) color_plate <- c("#FF0000", "#FF4D00", "#FF7000", "#FF8A00", "#FFA800", "#FFBF00", "#FFF000", "#FFFF54", "#AAFFFF","#7FFFFF", "#55FFFF", "#2AFFFF", "#00CFFF", "#20BFFF", "#209FFF", "#2060FF") zlim <- seq(0.08,0.40,by=0.04) temp[temp<min(zlim)] <- min(zlim) temp[temp>max(zlim)] <- max(zlim) image.plot(temp,col=color_plate, axis.args=list(cex.axis =1,at=zlim, labels=zlim,mgp=c(1, 0, 0),tck=0.1)) 

Answer 1

I received a response from the package creator package. Insert example code for others.

 library(fields) temp <- matrix( seq( 0,.5,,80), 8,10) colTab <- c("#FF0000", "#FF4D00","#FF7000", "#FF8A00", "#FF7000") N<- length( colTab) breaks <- seq(0.08, 0.40, length.out= N+1 ) image.plot(temp, col=colTab, breaks=breaks, axis.args=list(cex.axis =1, at=breaks, labels= breaks, mgp=c(1, 0, 0), tck=0.1) ) 

Answer 2

The best I could do to answer this question was to avoid the limitations of image.plot() and transcode the heat map into ggplot2 . The code I wrote should move your tags to the appropriate locations. Note that "Var1" and "Var2" in the ggplot p object may switch depending on how you want to display the data. I used melt() to convert the temp object, which means the original row / column designation is lost. I was not sure what was built on the x / y axis in the image.plot() function, so if I chose the wrong one, be sure to switch to "Var1" and "Var2" .

Hope this helps!

 library(fields) library(reshape2) library(ggplot2) library(grid) temp <- matrix(data=rexp(200, rate=10), nrow=180, ncol=360) color_palette <- c("#FF0000", "#FF4D00", "#FF7000", "#FF8A00", "#FFA800", "#FFBF00", "#FFF000", "#FFFF54", "#AAFFFF","#7FFFFF", "#55FFFF", "#2AFFFF", "#00CFFF", "#20BFFF", "#209FFF", "#2060FF") zlim <- seq(0.08,0.40,by=0.04) zlim2 <- seq(0.08,0.40,by=0.02) temp[temp<min(zlim)] <- min(zlim) temp[temp>max(zlim)] <- max(zlim) rownames(temp) <- seq(0,1,1/(length(temp[,1])-1)) colnames(temp) <- seq(0,1,1/(length(temp[1,])-1)) tdm <- melt(temp) tdm$val_for_color <- NA ##can change this as long as you end up with 17 classes (labeled 1-17) for color assignment for(i in 1:(length(zlim2)-1)){ tdm$val_for_color[which(tdm$value >= zlim2[[i]] & tdm$value <= zlim2[[i+1]] )] <- i } p <- ggplot(tdm, aes(x = Var1, y = Var2, fill = val_for_color)) + geom_raster() + scale_fill_gradientn(breaks=seq(1,length(zlim),1),colors=color_palette, labels=zlim)+ scale_x_continuous(expand=c(0,0)) + scale_y_continuous(expand=c(0,0)) + guides(fill = guide_colorbar(draw.ulim = TRUE,draw.llim = FALSE, barwidth = 0.7, barheight = 10, limits=c(min(zlim),max(zlim)), raster=FALSE, ticks=FALSE, title=NULL))+ ylab(NULL)+ xlab(NULL)+ theme_bw() g <- ggplotGrob(p) #this shifts and spreads the labels d <-g$grobs[[15]][[1]][[1]]$grobs[[3]]$y[[1]] g$grobs[[15]][[1]][[1]]$grobs[[3]]$y[[1]] <- g$grobs[[15]][[1]][[1]]$grobs[[3]]$y[[1]]-d for(i in 2:length(g$grobs[[15]][[1]][[1]]$grobs[[3]]$y)){ g$grobs[[15]][[1]][[1]]$grobs[[3]]$y[[i]] <- d*5*(i-1) } grid.draw(g)