How do I stop ggplot2 from rotating my matrix 90 degrees?
I am trying to create a heatmap using ggplot2 but I noticed that it rotates the matrix 90 degrees to the left when I draw it. This is very strange, and using coord_flip()
it t()
doesn't work because they rotate it to the left instead of the right (instead of fixing it, they create a heatmap that rotates 180 degrees). Are there any options or tricks to prevent this? Here's the relevant code:
#this is needed to run custHeat
zeroInterval <- function(mat, colors){
#modified version of findInterval such that zero is given its own category
#This function takes intervals as left exclusive, right inclusive.
#This is mostly so that intervals consisting of a single value will still be represented.
intervalMat <- matrix(0, nrow=nrow(mat), ncol=ncol(mat))
j <- 1
for(i in 1:(length(colors) - 1)){
if(colors[i] != colors[i+1]){
intervalMat[mat>colors[i] & mat<=colors[i+1]] <- j
j <- j + 1
} else {
intervalMat[mat==colors[i]] <- j
j <- j + 1
}
}
return(intervalMat)
}
#this actually plots the heatmap
custHeat <- function(M){
#create color bins/ranges for skewed matrix
color_bins <- c(-5, -4, -3, -2, -1, 0, 0, 1)
colors <- c('#67001F', '#B2182B', '#D6604D', '#F4A582', '#FDDBC7', "#FFFFFF", '#C6DBEF')
#create complete color palette
color_palette <- colorRampPalette(colors)(length(color_bins) - 1)
#This function assigns a number to each matrix value, so that it is colored correctly
mod_mat <- zeroInterval(random_matrix, color_bins)
## remove background and axis from plot
theme_change <- theme(
plot.background = element_blank(),
panel.grid.minor = element_blank(),
panel.grid.major = element_blank(),
panel.background = element_blank(),
panel.border = element_blank(),
axis.line = element_blank(),
axis.ticks = element_blank(),
axis.text.x = element_blank(),
axis.text.y = element_blank(),
axis.title.x = element_blank(),
axis.title.y = element_blank()
)
## output the graphics
ggplot(melt(mod_mat), aes(x = X1, y = X2, fill = factor(value))) +
geom_tile(color = "black") +
scale_fill_manual(values = color_palette, name = "") +
theme_change
}
##create random matrix, skewed toward negative values
random_matrix <- matrix(runif(100, min = -5, max = 1), nrow = 10)
random_matrix[1,] <- 0 #zeros should be at the top row of the heatmap
custHeat(random_matrix)
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You can counteract the rotation of the plotting function 90 degrees counterclockwise by first rotating the matrix 90 degrees in the other direction:
## An example matrix
(m <- matrix(1:9, ncol=3))
# [,1] [,2] [,3]
# [1,] 1 4 7
# [2,] 2 5 8
# [3,] 3 6 9
## The same matrix rotated 90 degrees clockwise
t(m)[,nrow(m):1]
# [,1] [,2] [,3]
# [1,] 3 2 1
# [2,] 6 5 4
# [3,] 9 8 7
Added later:
Some of R's build functions use the same convention image()
as others, while others do not. (Feel free to add to this list.)
m <- matrix(1:9, ncol=3)
## ------- These plotting functions DO rotate a matrix --------
## image()
image(m, col=blues9)
## levelplot() -- a lattice equivalent of image()
library(lattice)
levelplot(m, at=(1:10)-0.5, col.regions=blues9)
## Others
contour(m)
filled.contour(m, color=colorRampPalette(blues9))
persp(m)
lattice::contourplot(m)
lattice::wireframe(m) ## Nicely illustrates the logic of the indexing it uses
## ------- These plotting functions DO NOT --------
## imageRaster() -- a graphical primitive used by image(), among other functions
plot(0:1, 0:1, type="n", xlab="", ylab="")
rasterImage(matrix(blues9, ncol=3), 0,0,1,1, interpolate=FALSE)
## grid.raster() -- imageRaster() counterpart in the grid graphical system
library(grid)
grid.raster(matrix(blues9, ncol=3), interpolate=FALSE)
## plot(raster()) in raster package
library(raster)
plot(raster(m), col=blues9)
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