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 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(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))
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