如何自定义绘图上点的颜色和形状？

【问题标题】：How to customize color and shape of points on a plot?如何自定义绘图上点的颜色和形状？
【发布时间】：2021-08-25 20:38:09
【问题描述】：

我在下面创建了一个我想绘制的数据框

Sample <- c("A1","B1","C1","A1","B1","C1")
X <- c(1,1,2,4,3,5)
Y <- c(2,3,1,5,4,6)
df <- data.frame(Sample, X, Y)
df
 Sample X Y
1     A1 1 2
2     B1 1 3
3     C1 2 1
4     A1 4 5
5     B1 3 4
6     C1 5 6

ggplot(data = df, aes(x = X, y = Y, label = Sample)) +
  geom_point()

但是，我希望能够自定义每个点的颜色和形状。例如，我将如何使我的所有“A1”点都是红色和圆形，所有“B1”点都是蓝色和方形，所有“C1”点都是绿色和三角形？

【问题讨论】：

标签： r

【解决方案1】：

通常最简单的方法是映射这些美学，然后使用 scale_*_manual 定义它们的值：

ggplot(data = df, aes(x = X, y = Y, label = Sample, shape = Sample, color = Sample)) +
  geom_point(size = 3) +
  scale_shape_manual(values = c("A1" = 16, "B1" = 15, "C1" = 17)) +
  scale_color_manual(values = c("A1" = "red", "B1" = "blue", "C1" = "green"))

也可以将每个组指定为一个层，但这很快就会变得很麻烦，并且不适合拥有图例：

ggplot(df, aes(X, Y)) +
  geom_point(data = filter(df, Sample == "A1"), color = "red", shape = 16, size = 3) +
  geom_point(data = filter(df, Sample == "B1"), color = "blue", shape = 15, size = 3) +
  geom_point(data = filter(df, Sample == "C1"), color = "green", shape = 17, size = 3)

【讨论】：