geom_raster function - RDocumentation (2024)

Description

geom_rect() and geom_tile() do the same thing, but areparameterised differently: geom_rect() uses the locations of the fourcorners (xmin, xmax, ymin and ymax), whilegeom_tile() uses the center of the tile and its size (x,y, width, height). geom_raster() is a highperformance special case for when all the tiles are the same size, and nopattern fills are applied.

Usage

geom_raster( mapping = NULL, data = NULL, stat = "identity", position = "identity", ..., hjust = 0.5, vjust = 0.5, interpolate = FALSE, na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)

geom_rect( mapping = NULL, data = NULL, stat = "identity", position = "identity", ..., linejoin = "mitre", na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)

geom_tile( mapping = NULL, data = NULL, stat = "identity", position = "identity", ..., linejoin = "mitre", na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)

Arguments

mapping

Set of aesthetic mappings created by aes(). If specified andinherit.aes = TRUE (the default), it is combined with the default mappingat the top level of the plot. You must supply mapping if there is no plotmapping.

data

The data to be displayed in this layer. There are threeoptions:

If NULL, the default, the data is inherited from the plotdata as specified in the call to ggplot().

A data.frame, or other object, will override the plotdata. All objects will be fortified to produce a data frame. Seefortify() for which variables will be created.

A function will be called with a single argument,the plot data. The return value must be a data.frame, andwill be used as the layer data. A function can be createdfrom a formula (e.g. ~ head(.x, 10)).

stat

The statistical transformation to use on the data for thislayer, either as a ggproto Geom subclass or as a string naming thestat stripped of the stat_ prefix (e.g. "count" rather than"stat_count")

position

Position adjustment, either as a string naming the adjustment(e.g. "jitter" to use position_jitter), or the result of a call to aposition adjustment function. Use the latter if you need to change thesettings of the adjustment.

...

Other arguments passed on to layer(). These areoften aesthetics, used to set an aesthetic to a fixed value, likecolour = "red" or size = 3. They may also be parametersto the paired geom/stat.

hjust, vjust

horizontal and vertical justification of the grob. Eachjustification value should be a number between 0 and 1. Defaults to 0.5for both, centering each pixel over its data location.

interpolate

If TRUE interpolate linearly, if FALSE(the default) don't interpolate.

na.rm

If FALSE, the default, missing values are removed witha warning. If TRUE, missing values are silently removed.

show.legend

logical. Should this layer be included in the legends?NA, the default, includes if any aesthetics are mapped.FALSE never includes, and TRUE always includes.It can also be a named logical vector to finely select the aesthetics todisplay.

inherit.aes

If FALSE, overrides the default aesthetics,rather than combining with them. This is most useful for helper functionsthat define both data and aesthetics and shouldn't inherit behaviour fromthe default plot specification, e.g. borders().

linejoin

Line join style (round, mitre, bevel).

Aesthetics

geom_tile() understands the following aesthetics (required aesthetics are in bold):

  • x

  • y

  • alpha

  • colour

  • fill

  • group

  • height

  • linetype

  • linewidth

  • width

Note that geom_raster() ignores colour.

Learn more about setting these aesthetics in vignette("ggplot2-specs").

Details

geom_rect() and geom_tile()'s respond differently to scaletransformations due to their parameterisation. In geom_rect(), the scaletransformation is applied to the corners of the rectangles. In geom_tile(),the transformation is applied only to the centres and its size is determinedafter transformation.

Examples

Run this code

# The most common use for rectangles is to draw a surface. You always want# to use geom_raster here because it's so much faster, and produces# smaller output when saving to PDFggplot(faithfuld, aes(waiting, eruptions)) + geom_raster(aes(fill = density))# Interpolation smooths the surface & is most helpful when rendering images.ggplot(faithfuld, aes(waiting, eruptions)) + geom_raster(aes(fill = density), interpolate = TRUE)# If you want to draw arbitrary rectangles, use geom_tile() or geom_rect()df <- data.frame( x = rep(c(2, 5, 7, 9, 12), 2), y = rep(c(1, 2), each = 5), z = factor(rep(1:5, each = 2)), w = rep(diff(c(0, 4, 6, 8, 10, 14)), 2))ggplot(df, aes(x, y)) + geom_tile(aes(fill = z), colour = "grey50")ggplot(df, aes(x, y, width = w)) + geom_tile(aes(fill = z), colour = "grey50")ggplot(df, aes(xmin = x - w / 2, xmax = x + w / 2, ymin = y, ymax = y + 1)) + geom_rect(aes(fill = z), colour = "grey50")# \donttest{# Justification controls where the cells are anchoreddf <- expand.grid(x = 0:5, y = 0:5)set.seed(1)df$z <- runif(nrow(df))# default is compatible with geom_tile()ggplot(df, aes(x, y, fill = z)) + geom_raster()# zero paddingggplot(df, aes(x, y, fill = z)) + geom_raster(hjust = 0, vjust = 0)# Inspired by the image-density plots of Ken Knoblauchcars <- ggplot(mtcars, aes(mpg, factor(cyl)))cars + geom_point()cars + stat_bin_2d(aes(fill = after_stat(count)), binwidth = c(3,1))cars + stat_bin_2d(aes(fill = after_stat(density)), binwidth = c(3,1))cars + stat_density( aes(fill = after_stat(density)), geom = "raster", position = "identity" )cars + stat_density( aes(fill = after_stat(count)), geom = "raster", position = "identity" )# }

Run the code above in your browser using DataLab

geom_raster function - RDocumentation (2024)
Top Articles
Latest Posts
Recommended Articles
Article information

Author: Kerri Lueilwitz

Last Updated:

Views: 5533

Rating: 4.7 / 5 (67 voted)

Reviews: 90% of readers found this page helpful

Author information

Name: Kerri Lueilwitz

Birthday: 1992-10-31

Address: Suite 878 3699 Chantelle Roads, Colebury, NC 68599

Phone: +6111989609516

Job: Chief Farming Manager

Hobby: Mycology, Stone skipping, Dowsing, Whittling, Taxidermy, Sand art, Roller skating

Introduction: My name is Kerri Lueilwitz, I am a courageous, gentle, quaint, thankful, outstanding, brave, vast person who loves writing and wants to share my knowledge and understanding with you.