I'm tinkering with geom_point trying to plot the following code. I have converted cars$vs to a factor with discrete levels so that I can visualize both levels of that variable in different colors by assigning it to "fill" in the ggplot aes settings.
cars <- mtcars
cars$vs <- as.factor(cars$vs)
ggplot(cars,aes(x = mpg, y = disp, fill = vs)) +
geom_point(size = 4) +
scale_fill_discrete(name = "Test")
As you can see, the graph does not differentiate between both "fill" conditions via color. However, it preserves the legend label I have specified in scale_fill_discrete.
Alternatively, I can plot the following (same code, but instead of "fill", use "color")
cars <- mtcars
cars$vs <- as.factor(cars$vs)
ggplot(cars,aes(x = mpg, y = disp, color = vs)) +
geom_point(size = 4) +
scale_fill_discrete(name = "Test")
As you can see, using "color" instead of "fill" differentiates between the levels of the factor via color, but seems to override any changes I make to the legend title using scale_fill_discrete.
Am I using "fill" incorrectly? How can I plot different levels of a factor in different colors using this method and have control over the plot legend vis scale_fill_discrete?
To use a fill
with geom_point
you should use a fill-able shape:
ggplot(cars,aes(x = mpg, y = disp, fill = vs)) +
geom_point(size = 4, shape = 21) +
scale_fill_discrete(name = "Test")
See ?pch
, which shows that shapes 21 to 25 can be colored and filled with different colors. ggplot
will not use the fill
unless the shape is one that is fill-able. This behavior has changed a bit in different versions, as seen in the NEWS file .
There's no reason to use fill
with geom_point
unless you want the outline and fill colors of the points to be different, so the other answer recommending color
is probably what you want.
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