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
｜
271
ggpairs 函数功能很强，但不是特别快。如果你只是进行交互式工作并希望快速查看数
据，则基础 R 的 plot 函数可提供更快的输出（见图 10-25 ）。
plot(iris)
Sepal.Length
Sepal.Width
Petal.Length
Species
Petal.Width
1.0 2.0 3.0
2.0 3.0 4.0 0.5 1.5 2.5
4.5 6.0 7.5 1 3 5 7
0.5 2.5
1.0 2.5 1 4 7 4.5 7.0
2.0 4.0
图 10-25：
plot
函数生成的成对图
虽然 ggpairs 函数的绘制速度不如基础 R 中 plot 函数快，但它能在对角线上生成密
度图，并在图的上三角中报告相关性。当存在因子或字符列时，ggpairs 会在图形的下
三角中给出柱状图，在图形的上三角中给出箱线图。这些是理解数据关系的很好补充。
10.9 创建多个分组的散点图
10.9.1 问题
数据集包含（至少）两个数值型变量以及一个定义组的因子或字符字段。需要为数值型
变量创建多个散点图，每个水平的因子或字符字段都有一个散点图。
10.9.2 解决方案
我们通过在图形中加入 facet_wrap，在 ggplot 中绘制这种称为条件图的图形。在这
个例子中，我们使用数据框 df，它包含三列
x
、
y
和
f
，
f
是一个因子（或一个字符串）：
ggplot(df, aes(x, y)) +
geom_point() +
facet_wrap( ~ f)
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10
章
10.9.3 ...
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