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我正在使用pls包装中的 PLS 回归研究感官数据和化学测量之间的相关性。最终，我想在相关加载图中显示结果，如下例所示。到目前为止，我设法用 X 和 Y 相关矩阵制作了图，但我还没有想出一种方法来将观察结果投影到图上。

![与观察的相关图](https://www.google.no/url?sa=i&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjL8buTiZXeAhVDBiwKHSPKDWgQjhx6BAgBEAM&url=https%3A%2F%2Fwww.xlstat.com%2Fen%2Fsolutions% 2Ffeatures%2F偏最小二乘回归&psig=AOvVaw3NOfDzBjMZFcn-TXm16KaX&ust=1540126569608484)

例如，我使用包中的oliveoil数据集pls。我计算了相关负载（使用此处描述的方法）并使用创建了相关图ggplot2（这可以使用plsdepot包以简单的方式完成，但我喜欢多功能性ggplot）：

library(pls)
data("oliveoil")
oil <- plsr(sensory ~ chemical, scale = TRUE, data = oliveoil)

scores <- oil$scores
sc1 <- scores[,1]
sc2 <- scores[,2]
scores <- as.data.frame(cbind(sc1, sc2))
cl_plsr <- cor(model.matrix(oil), scores)
df_cor <- as.data.frame(cl_plsr)
df_depend_cor <- as.data.frame(cor(oliveoil$sensory, scores))
plot_loading_correlation  <-  rbind(df_cor, df_depend_cor)
plot_loading_correlation1 <- setNames(plot_loading_correlation, c("comp1", "comp2"))

#Function to draw circle
circleFun <- function(center = c(0,0),diameter = 1, npoints = 100){
  r = diameter / 2
  tt <- seq(0,2*pi,length.out = npoints)
  xx <- center[1] + r * cos(tt)
  yy <- center[2] + r * sin(tt)
  return(data.frame(x = xx, y = yy))
}

dat_plsr <- circleFun(c(0,0),2,npoints = 100)

library(ggplot2)
library(ggrepel)

p <- ggplot(data=plot_loading_correlation1, aes(comp1, comp2))+
  theme_bw() +
  geom_hline(aes(yintercept = 0), size=.2, linetype = 3)+ 
  geom_vline(aes(xintercept = 0), size=.2, linetype = 3)+
  geom_text_repel(aes(label = rownames(plot_loading_correlation1), 
              colour = c("black","black","black","black","black", 
                         "red","red","red","red","red","red")))+
  scale_color_manual(values=c("blue","red"))+
  scale_x_continuous(breaks = seq(-1,2.5, by=0.5))+
  scale_y_continuous(breaks = seq(-1.5,2.5, by=0.5))+
  coord_fixed(ylim=c(-1, 1), xlim=c(-1, 1)) + xlab("PC 1") + ylab("PC 2")+ 
  geom_path(data=dat_plsr ,
        aes(x,y), colour = "darkgrey")+
  theme(legend.title=element_blank())+
  theme(axis.ticks = element_line(colour = "black"))+
  theme(axis.title = element_text(colour = "black"))+
  theme(axis.text = element_text(color="black"))+
  theme(legend.position='none')+
  theme(panel.grid.minor = element_blank()) +
  theme(panel.grid.major = element_blank()) +
  geom_point(data = plot_loading_correlation1,
         aes(x=comp1, y=comp2), 
         colour = c("blue","blue","blue","blue","blue",
                    "red","red","red","red","red","red"), 
         shape = c(21,21,21,21,21,22,22,22,22,22,22),          
         fill = c("blue","blue","blue","blue","blue",
                  "red","red","red","red","red","red"),
         size = 2.2)
p

来自 ggplot2 的相关加载图，没有观察结果

如上例所示，如何将单个观察结果投影到该图？是否应该对分数进行缩放以使其适合相关负载量表（从 -1 到 1）？这在科学上是否可以接受？

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