如何将图例添加到 geom_point PCA 图？

Question

我已经制作了一个 PCA 图，但我正在努力如何在其中获得一个图例（对 R 来说很新）

这是代码，包括颜色的向量。

pca_cols <- c("seagreen3","seagreen3","seagreen3","seagreen3","seagreen3","seagreen3","steelblue","steelblue","steelblue","steelblue")

ggplot(datascores12, aes(x=PC1, y=PC2))+
  geom_point(size=3,fill=pca_cols, shape = 21)+
  xlab(paste("PC1 ", "(",data_exp12[1],"%)", sep=""))+
  ylab(paste("PC2 ", "(",data_exp12[2],"%)", sep=""))+
  theme(axis.title.y = element_text(face = "bold"),
             legend.text = element_text(face = "bold"),
             axis.text.x = element_text(face = "bold"),
             axis.text.y = element_text(face = "bold"),
             axis.title.x = element_text(face = "bold"),
             legend.title = element_text(face = "bold"),
             panel.grid.major = element_line(size = 0.25, linetype = 'dashed',
                                             colour = "grey"),
             panel.grid.minor = element_line(size = 0.25, linetype = 'dashed',
                                             colour = "grey"),
             panel.background = element_blank(),
             axis.line = element_line(colour = "black"),
             plot.title = element_text(face = "bold", size = 10, hjust = 0.5))+
  theme(legend.position = "bottom", legend.title = element_blank())

制作这个情节：

enter image description here

我想在底部加个图例，切不明白！

提前致谢

Answer 1

为了让您看到图例，您需要将该参数包含在 aes() 内的图例中。因此，将geom_point 行更改为：

geom_point(size=3,fill=pca_cols, shape = 21)

忠告：让ggplot 决定如何根据数据集中的变量为数据点应用美感会更容易且更好。举个简单的例子：

# dummy dataset
df <- data.frame(
        x=sample(1:20,20),
        y=rnorm(20,1,0.1),
        group=c('A', 'B')
    )

# color specifications
cols <- list('A'='red', 'B'='blue')

# plot
ggplot(df, aes(x,y)) +
    geom_point(aes(fill=group), shape=21, size=3) +
    theme_bw() +
    scale_fill_manual(values = cols)

ggplot 根据位置和编码为因子的数据帧中的变量“组”决定如何填充每个点。