1

Actually I am trying to plot PCA by this package but when I plot the loading, I cannot change the legend as I wish (e.g. if I want to set the legend to (+)M it shows something else. what I do is as follows: 

library(ggbiplot)
require(ggplot2)

data(iris)
data <- data.frame(iris[,1:4])    
ir.pca <- prcomp(data, center = TRUE, scale. = TRUE)
theta <- seq(0,2*pi,length.out = 100)
circle <- data.frame(x = cos(theta), y = sin(theta))
p <- ggplot(circle,aes(x,y)) + geom_path()

loadings <- data.frame(ir.pca$rotation, 
                       .names = row.names(ir.pca$rotation))
p + geom_text(data=loadings, 
              mapping=aes(x = PC1, y = PC2, label = .names, colour = .names)) +
  coord_fixed(ratio=1) +
  labs(x = "PC1", y = "PC2")

Now the problem is if you change the name of the variables to for example (+)C , (-)C, (*)C and (%)C then plot, it shows something else in legend instead

on the other hand, the title of the legend is .name , how to also set this to something else?

  • What is `log.ir`? Your code's not reproducible without it. – eipi10 May 08 '15 at 17:17
  • I'm not sure what you mean by "changing the names of the variables..shows something else." Can you be more specific or post an image showing what you're getting and explaining what you want? For your second question, you can change the legend title by adding the following to your call to `labs`: `colour="New Label"`. – eipi10 May 08 '15 at 17:29
  • @eipi10 I modified the question and now it is reproducible –  May 11 '15 at 11:59

1 Answers1

1

Is this what you mean, or am I misunderstanding:

loadings <- data.frame(ir.pca$rotation, 
                       .names = row.names(ir.pca$rotation),
                       names2 = c("(+)C" , "(-)C", "(*)C", "(%)C"))

p + geom_text(data=loadings, 
              mapping=aes(x = PC1, y = PC2, label = names2, colour = .names)) +
  coord_fixed(ratio=1) +
  labs(x = "PC1", y = "PC2", colour="Legend Title")

enter image description here

UPDATE: Here's how to make text bold in geom_text and in the legend:

p + geom_text(data=loadings, 
              mapping=aes(x = PC1, y = PC2, label = names2, colour = .names),
              fontface="bold") +
  coord_fixed(ratio=1) +
  labs(x = "PC1", y = "PC2", colour="Legend Title") +
  theme(legend.text=element_text(face="bold"))
eipi10
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