ggplot2---Guide:axes and legends---Legend guide

Legend guide

图例说明
Legend type guide shows key (i.e., geoms) mapped onto values. Legend guides for various scales are integrated if possible.
图例上显示关键字(即:(geoms)映射到值上。如果可能的话，图例可以整合到各种各样的标尺上。

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, ...)

参数

keywidth

A numeric or a unit object specifying the width of the legend key. Default value islegend.key.width or legend.key.size in theme or theme.
图例的宽度

keyheight

A numeric or a unit object specifying the height of the legend key. Default value islegend.key.height or legend.key.size in theme or theme.
图例的高度

direction

A character string indicating the direction of the guide. One of "horizontal" or "vertical."
字符串的方向，水平或者竖直

default.unit

A character string indicating unit for keywidth and keyheight.
字符表示单元格关键字的宽度和高度

override.aes

A list specifying aesthetic parameters of legend key. See details and examples.
指定图例美学参数？？？

nrow

The desired number of rows of legends.
图例的行数

ncol

The desired number of column of legends.
图例的列数

byrow

logical. If FALSE (the default) the legend-matrix is filled by columns, otherwise the legend-matrix is filled by rows.
符合逻辑的。如果FALSE(默认)是图例按列填充，否则按行填充。

Examples
df <- reshape2::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 formp1 + 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(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 = 0 ) ))

# label position
p1 + guides(fill = guide_legend(label.position = "left", label.hjust = 1))

# 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 = 1, label.theme = element_text(angle = 90) ))

# Set aesthetic of legend key
# very low alpha value make it difficult to see legend key
p3 <- ggplot(diamonds, aes(carat, price)) + geom_point(aes(colour = color), alpha = 1/100)
p3

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

# multiple row/col legends
df <- data.frame(x = 1:20, y = 1:20, color = letters[1:20])p <- ggplot(df, aes(x, y)) + geom_point(aes(colour = color))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))