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, ...)Examples

library(reshape2) # for meltdf <- 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 titlep1 + 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 sizep1 + guides(fill = guide_legend(keywidth = 3, keyheight = 1))

# title positionp1 + guides(fill = guide_legend(title = "LEFT", title.position = "left"))

# title text styles via element_textp1 + guides(fill = guide_legend(  title.theme = element_text(size=15, face="italic", colour = "red", angle = 45)))

# label positionp1 + guides(fill = guide_legend(label.position = "bottom"))

# label stylesp1 + 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 keyp3 <- qplot(carat, price, data = diamonds, colour = color,  alpha = I(1/100))p3

# override.aes overwrites the alphap3 + guides(colour = guide_legend(override.aes = list(alpha = 1)))

# multiple row/col legendsp <- 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 legendp + guides(col = guide_legend(reverse = TRUE))