p <- ggplot(mtcars, aes(wt, mpg))

p + geom_point()

# Add aesthetic mappings

p + geom_point(aes(colour = qsec))

p + geom_point(aes(alpha = qsec))

p + geom_point(aes(colour = factor(cyl)))

p + geom_point(aes(shape = factor(cyl)))

p + geom_point(aes(size = qsec))

# Change scales

p + geom_point(aes(colour = cyl)) + scale_colour_gradient(low ="blue")

p + geom_point(aes(size = qsec)) + scale_area()

scale_area is deprecated. Usescale_size_area instead.

Note that the behavior of scale_size_area is slightly different:

  bydefault it makes the area proportional to the numeric value. (Deprecated; lastused in version 0.9.2)

p + geom_point(aes(shape = factor(cyl))) + scale_shape(solid = FALSE)

# Set aesthetics to fixed value

p + geom_point(colour = "red", size = 3)

qplot(wt, mpg, data = mtcars, colour = I("red"), size = I(3))

# Varying alpha is useful for large datasets

d <- ggplot(diamonds, aes(carat, price))

d + geom_point(alpha = 1/10)

d + geom_point(alpha = 1/20)

d + geom_point(alpha = 1/100)

# You can create interesting shapes by layering multiple points of

# different sizes

p <- ggplot(mtcars, aes(mpg, wt))

p + geom_point(colour="grey50", size = 4) +geom_point(aes(colour = cyl))

p + aes(shape = factor(cyl)) +

  geom_point(aes(colour =factor(cyl)), size = 4) +

geom_point(colour="grey90", size = 1.5)

p + geom_point(colour="black", size = 4.5) +

geom_point(colour="pink", size = 4) +

  geom_point(aes(shape =factor(cyl)))

# These extra layers don't usually appear in the legend, but we can

# force their inclusion

p + geom_point(colour="black", size = 4.5, show_guide = TRUE) +

geom_point(colour="pink", size = 4, show_guide = TRUE) +

  geom_point(aes(shape =factor(cyl)))

# Transparent points:

qplot(mpg, wt, data = mtcars, size = I(5), alpha = I(0.2))

# geom_point warns when missing values have been dropped from the data set

# and not plotted, you can turn this off by setting na.rm = TRUE

mtcars2 <- transform(mtcars, mpg = ifelse(runif(32) < 0.2, NA, mpg))

qplot(wt, mpg, data = mtcars2)

Warning message:

Removed 11 rows containing missing values(geom_point).

qplot(wt, mpg, data = mtcars2, na.rm = TRUE)

# Use qplot instead

qplot(wt, mpg, data = mtcars)

qplot(wt, mpg, data = mtcars, colour = factor(cyl))

qplot(wt, mpg, data = mtcars, colour = I("red"))