gf_raster: Formula interface to geom_raster()

Description

ggformula functions provide a formula interface to ggplot2 layer functions. For plots with just one layer, the formula interface is more compact and is consistent with modeling and mosaic notation.

Usage

gf_raster(object = NULL, gformula = NULL, data = NULL, geom = "raster",
  stat = "identity", position = "identity", show.legend = NA,
  show.help = NULL, inherit = TRUE, ...)

Arguments

object

When chaining, this holds an object produced in the earlier portions of the chain. Most users can safely ignore this argument. See details and examples.

gformula

A formula with shape y ~ x. Faceting can be achieved by including | in the formula.

data

A data frame with the variables to be plotted.

geom

A character string naming the geom used to make the layer.

stat

A character string naming the stat used to make the layer.

position

Either a character string naming the position function used for the layer or a position object returned from a call to a position function.

show.legend

A logical indicating whether this layer should be included in the legends. NA, the default, includes layer in the legends if any of the attributes of the layer are mapped.

show.help

If TRUE, display some minimal help.

inherit

A logical indicating whether default attributes are inherited.

...

Additional arguments. Typically these are (a) ggplot2 aesthetics to be set with attribute = value, (b) ggplot2 aesthetics to be mapped with attribute = ~expression, or (c) attributes of the layer as a whole, which are set with attribute = value. Available attributes include alpha, color, fill, group, linetype, size, hjust, vjust, interpolate

Value

a gg object

Details

Positional aesthetics are typically specified using a formula (see the gformula argument). Setting and mapping of additional attributes can be done through the use of additional arguments. Attributes can be set can be set using arguments of the form attribute = value or mapped using arguments of the form attribute = ~ expression.

In formulas of the form A | B, B will be used to form facets using facet_wrap() or facet_grid(). This provides an alternative to gf_facet_wrap() and gf_facet_grid() that is terser and may feel more familiar to users of lattice.

Evaluation of the ggplot2 code occurs in the environment of gformula. This will typically do the right thing when formulas are created on the fly, but might not be the right thing if formulas created in one environment are used to create plots in another.

Examples

Run this code

# NOT RUN {
# Justification controls where the cells are anchored
D <- expand.grid(x = 0:5, y = 0:5)
D$z <- runif(nrow(D))
# centered squares
gf_raster(z ~ x + y, data = D)
gf_raster(y ~ x, fill = ~ z, data = D)
# zero padding
gf_raster(z ~ x + y, data = D, hjust = 0, vjust = 0)
# }