ggplot2 (version 0.9.1)

geom_tile: Tile plane with rectangles.

Description

Similar to levelplot and image.

Usage

geom_tile(mapping = NULL, data = NULL, stat = "identity",
    position = "identity", ...)

Arguments

mapping

The aesthetic mapping, usually constructed with aes or aes_string. Only needs to be set at the layer level if you are overriding the plot defaults.

data

A layer specific dataset - only needed if you want to override the plot defaults.

stat

The statistical transformation to use on the data for this layer.

position

The position adjustment to use for overlappling points on this layer

...

other arguments passed on to layer. This can include aesthetics whose values you want to set, not map. See layer for more details.

Examples

# Generate data
pp <- function (n,r=4) {
 x <- seq(-r*pi, r*pi, len=n)
 df <- expand.grid(x=x, y=x)
 df$r <- sqrt(df$x^2 + df$y^2)
 df$z <- cos(df$r^2)*exp(-df$r/6)
 df
}
p <- ggplot(pp(20), aes(x=x,y=y))

p + geom_tile() #pretty useless!

# Add aesthetic mappings
p + geom_tile(aes(fill=z))

# Change scale
p + geom_tile(aes(fill=z)) + scale_fill_gradient(low="green", high="red")

# Use qplot instead
qplot(x, y, data=pp(20), geom="tile", fill=z)
qplot(x, y, data=pp(100), geom="tile", fill=z)

# Missing values
p <- ggplot(pp(20)[sample(20*20, size=200),], aes(x=x,y=y,fill=z))
p + geom_tile()

# Input that works with image
image(t(volcano)[ncol(volcano):1,])
library(reshape2) # for melt
ggplot(melt(volcano), aes(x=Var1, y=Var2, fill=value)) + geom_tile()

# inspired by the image-density plots of Ken Knoblauch
cars <- ggplot(mtcars, aes(y=factor(cyl), x=mpg))
cars + geom_point()
cars + stat_bin(aes(fill=..count..), geom="tile", binwidth=3, position="identity")
cars + stat_bin(aes(fill=..density..), geom="tile", binwidth=3, position="identity")

cars + stat_density(aes(fill=..density..), geom="tile", position="identity")
cars + stat_density(aes(fill=..count..), geom="tile", position="identity")

# Another example with with unequal tile sizes
x.cell.boundary <- c(0, 4, 6, 8, 10, 14)
example <- data.frame(
  x = rep(c(2, 5, 7, 9, 12), 2),
  y = factor(rep(c(1,2), each=5)),
  z = rep(1:5, each=2),
  w = rep(diff(x.cell.boundary), 2)
)

qplot(x, y, fill=z, data=example, geom="tile")
qplot(x, y, fill=z, data=example, geom="tile", width=w)
qplot(x, y, fill=factor(z), data=example, geom="tile", width=w)

# You can manually set the colour of the tiles using
# scale_manual
col <- c("darkblue", "blue", "green", "orange", "red")
qplot(x, y, fill=col[z], data=example, geom="tile", width=w, group=1) + scale_fill_identity(labels=letters[1:5], breaks=col)