R语言 循环作图

setwd("C:\\Users\\Administrator\\Desktop\\pic")
# Plot separate ggplot figures in a loop. 
library(ggplot2) 

# Make list of variable names to loop over. 
var_list = combn(names(iris)[1:3], 2, simplify=FALSE) 

# Make plots. 
plot_list = list() 
for (i in 1:3) { 
  p = ggplot(iris, aes_string(x=var_list[[i]][1], y=var_list[[i]][2])) + 
    geom_point(size=3, aes(colour=Species)) 
  plot_list[[i]] = p 
} 

# Save plots to tiff. Makes a separate file for each plot. 
for (i in 1:3) { 
  file_name = paste("iris_plot_", i, ".tiff", sep="") 
  tiff(file_name) 
  print(plot_list[[i]]) 
  dev.off() 
} 

# Another option: create pdf where each page is a separate plot. 
pdf("plots.pdf") 
for (i in 1:3) { 
  print(plot_list[[i]]) 
} 
dev.off()