June 2020
Beginner to intermediate
522 pages
9h 6m
Chinese
Content preview from R 语言经典实例（原书第 2 版）
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图形
｜
263
如果我们按物种区分点，那么图形将提供更多信息。除了通过形状区分物种外，我们
还可以通过颜色区分。我们可以在 aes 调用中添加 shape = Species 和 color =
Species，以使每个物种具有不同的形状和颜色，如图 10-15 所示。
ggplot(data = iris,
aes(
x = Petal.Length,
y = Petal.Width,
shape = Species,
color = Species
)) +
geom_point()
Petal.Length
Petal.Width
2.5
2.0
1.5
1.0
0.5
0.0
4 62
Species
setosa
versicolor
virginica
图 10-15：
iris
：形状和颜色
ggplot 也为你设置了一个图例，可以很方便地使用。
10.5.4 另请参阅
有关如何添加图例的更多信息，请参阅 10.6 节。
10.6 添加（或去除）图例
10.6.1 问题
图形需要包含一个
图例
，即添加小方框为读者解释图形中的元素。
10.6.2 解决方案
在大多数情况下，ggplot 会自动添加图例，如上一节中所示。但是如果我们在 aes
264
｜
第
10
章
函数中没有明确的分组，那么 ggplot 默认情况下不会显示图例 ...
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