r - GGbiplot 一些数据点的一些额外颜色

Question

是否可以ggbiplot在 R 的包中用另一种颜色标记一些特殊的数据点，如数据点，Alcohol = 13.2然后在集群中。我想强调一些特定的数据点。

data(wine)
wine.pca <- prcomp(wine, scale. = TRUE)
print(ggbiplot(wine.pca, obs.scale = 1, var.scale = 1, groups = wine.class, 
   ellipse = TRUE, circle = TRUE))

标签： rggbiplot

Answer 1

我不确定这是否可以在ggbiplot调用中完成，但肯定可以通过添加另一层来完成。这是一个例子：

library(ggbiplot)

data(wine)
wine.pca <- prcomp(wine, scale. = TRUE)
p <- ggbiplot(wine.pca, obs.scale = 1, var.scale = 1, groups = wine.class, 
               ellipse = TRUE, circle = TRUE)

现在子集您要突出显示的点：

wine.pca$x[wine$Alcohol == 13.2, 1:2, drop = FALSE] #drop = FALSE to keep matrix class

并提供data以下内容geom_point：

p + geom_point(data = wine.pca$x[wine$Alcohol == 13.2, 1:2, drop = FALSE],
              aes(x = PC1, y = PC2), color = "black")

你也可以这样做：

p + geom_point(data = wine.pca$x[wine$Alcohol == 13.2, 1:2, drop = FALSE],
               aes(x = PC1, y = PC2), color = "black", shape = 21, size = 7)

但是，如果您想强调很多点，这可能太多了：

p + geom_point(data = wine.pca$x[wine$Alcohol >= 13.2, 1:2],
               aes(x = PC1, y = PC2), color = "black", shape = 21, size = 7)