guide_legend: Legend guide.

Description

Legend type guide shows key (i.e., geoms) mapped onto values. Legend guides for various scales are integrated if possible.

Usage

guide_legend(title = waiver(), title.position = NULL,
    title.theme = NULL, title.hjust = NULL,
    title.vjust = NULL, label = TRUE,
    label.position = NULL, label.theme = NULL,
    label.hjust = NULL, label.vjust = NULL,
    keywidth = NULL, keyheight = NULL, direction = NULL,
    default.unit = "line", override.aes = list(),
    nrow = NULL, ncol = NULL, byrow = FALSE,
    reverse = FALSE, order = 0, ...)

Arguments

title

A character string or expression indicating a title of guide. If NULL, the title is not shown. By default (waiver), the name of the scale object or tha name specified in

title.position

A character string indicating the position of a title. One of "top" (default for a vertical guide), "bottom", "left" (default for a horizontal guide), or "right."

title.theme

A theme object for rendering the title text. Usually the object of element_text is expected. By default, the theme is specified by legend.title in

title.hjust

A number specifying horizontal justification of the title text.

title.vjust

A number specifying vertical justification of the title text.

label

logical. If TRUE then the labels are drawn. If FALSE then the labels are invisible.

label.position

A character string indicating the position of a label. One of "top", "bottom" (default for horizontal guide), "left", or "right" (default for vertical gudie).

label.theme

A theme object for rendering the label text. Usually the object of element_text is expected. By default, the theme is specified by legend.text in

label.hjust

A numeric specifying horizontal justification of the label text.

label.vjust

A numeric specifying vertical justification of the label text.

keywidth

A numeric or a unit object specifying the width of the legend key. Default value is legend.key.width or legend.key.size in theme or theme.

keyheight

A numeric or a unit object specifying the height of the legend key. Default value is legend.key.height or legend.key.size in theme or theme.

direction

A character string indicating the direction of the guide. One of "horizontal" or "vertical."

default.unit

A character string indicating unit for keywidth and keyheight.

override.aes

A list specifying aesthetic parameters of legend key. See details and examples.

nrow

The desired number of rows of legends.

ncol

The desired number of column of legends.

byrow

logical. If FALSE (the default) the legend-matrix is filled by columns, otherwise the legend-matrix is filled by rows.

reverse

logical. If TRUE the order of legends is reversed.

order

positive integer less that 99 that specify the order of this guide in the multiple guides. If 0 (default), the order is determined by a secret algorithm.

...

ignored.

Value

A guide object

Details

Guides can be specified in each scale or in guides. guide="legend" in scale is syntactic sugar for guide=guide_legend(). As for how to specify the guide for each scales in more detail, see guides.

Examples

Run this code

library(reshape2) # for melt
df <- melt(outer(1:4, 1:4), varnames = c("X1", "X2"))

p1 <- ggplot(df, aes(X1, X2)) + geom_tile(aes(fill = value))
p2 <- p1 + geom_point(aes(size = value))

# Basic form
p1 + scale_fill_continuous(guide = "legend")
p1 + scale_fill_continuous(guide = guide_legend())

# Guide title

p1 + scale_fill_continuous(guide = guide_legend(title = "V")) # title text
p1 + scale_fill_continuous(name = "V") # same
p1 + scale_fill_continuous(guide = guide_legend(title = NULL)) # no title

# Control styles

# key size
p1 + guides(fill = guide_legend(keywidth = 3, keyheight = 1))

# title position
p1 + guides(fill = guide_legend(title = "LEFT", title.position = "left"))

# title text styles via element_text
p1 + guides(fill = guide_legend(
  title.theme = element_text(size=15, face="italic", colour = "red", angle = 45)))

# label position
p1 + guides(fill = guide_legend(label.position = "bottom"))

# label styles
p1 + scale_fill_continuous(breaks = c(5, 10, 15),
  labels = paste("long", c(5, 10, 15)),
  guide = guide_legend(direction = "horizontal", title.position = "top",
    label.position="bottom", label.hjust = 0.5, label.vjust = 0.5,
    label.theme = element_text(angle = 90)))

# Set aesthetic of legend key

# very low alpha value make it difficult to see legend key
p3 <- qplot(carat, price, data = diamonds, colour = color,
  alpha = I(1/100))
p3

# override.aes overwrites the alpha
p3 + guides(colour = guide_legend(override.aes = list(alpha = 1)))

# multiple row/col legends
p <- qplot(1:20, 1:20, colour = letters[1:20])
p + guides(col = guide_legend(nrow = 8))
p + guides(col = guide_legend(ncol = 8))
p + guides(col = guide_legend(nrow = 8, byrow = TRUE))
p + guides(col = guide_legend(ncol = 8, byrow = TRUE))

# reversed order legend
p + guides(col = guide_legend(reverse = TRUE))

Run the code above in your browser using DataLab