ggbiplot更改点大小

Question

是否有人知道如何改变点的大小，并且仍然保持下面代码中的组颜色？

只需添加geom_point(size = 8)即可将所有点的颜色更改为黑色。

代码：

library(ggbiplot)
data(wine)
wine.pca <- prcomp(wine, scale. = TRUE)
g <- ggbiplot(wine.pca, obs.scale = 1, var.scale = 1, 
              groups = wine.class, varname.size = 8, labels.size=10  , ellipse = TRUE, circle = TRUE)
g <- g + scale_color_discrete(name = '') #+  geom_point(size = 8)
g <- g + opts(legend.direction = 'horizontal', 
              legend.position = 'top')
print(g)

Answer 1

在geom_point中添加颜色美学将保留按组着色的点。另外，我将opts更改为theme，因为opts已被废弃。

ggbiplot(wine.pca, obs.scale = 1, var.scale = 1, group=wine.class,
              varname.size = 8, labels.size=10, 
              ellipse = TRUE, circle = TRUE) +
  scale_color_discrete(name = '') +  
  geom_point(aes(colour=wine.class), size = 8) +
  theme(legend.direction ='horizontal', 
        legend.position = 'top')

Answer 2

我在试图使我的观点变小的时候遇到了这个问题。eipi10的答案确实很好地解决了这个问题，只需简单地绘制默认的点，就可以使点更大。虽然这是一个简单的解决方案，但我可以提出以下建议，通过设置alpha=0并绘制上述geom_point行中的点，使默认点不可见：

ggbiplot(wine.pca, obs.scale = 1, var.scale = 1, group=wine.class,
     varname.size = 8, labels.size=10, 
     ellipse = TRUE, circle = TRUE,
     alpha=0 #here's the change
) + 
scale_color_discrete(name = '') +  
geom_point(aes(colour=wine.class), size = 0.5) +  #set size of smaller points here
theme(legend.direction ='horizontal', 
    legend.position = 'top')