Save multiple ggplots using a for loop

Question

I want to automate the generation of a number of ggplots:

Generic dataset:

mydata<-data.frame(matrix(rnorm(100),ncol=5)) names(mydata)<-c("Tijd","X1","X2","X3","X4")  

Specify variables to include:

Start=2 Stop=5 

List to save the plots in:

gvec<-vector("list",length=length(Start:Stop)) 

Create plots:

for(i in Start:Stop){   graphy<-ggplot(mydata,aes_string(x="Tijd",y=names(mydata)[i]))+geom_point()+mytheme   gvec[[i-Start+1]]<-graphy } 

Save plots:

for(i in Start:Stop){ tiff(paste0("Test/Residu/Plots/Prei/mydata.",names(mydata)[i],"09.14.tiff"),width=720,height=720) gvec[[i-Start+1]] graphics.off() } 

The list of plots is generated; I can save the plots manually as well. However, using the last loop the files generated are all blank. I can't figure out the reason for this.

As per Roland's suggestion I tried print(gvec[[i-Start+1]]) but I still get blank files as output.

Answer 1

Here is a fully reproducible example of creating ggplots in a loop.

# 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() 

Answer 2

You can also use the ggsave function from ggplot2 library.

library(ggplot2) data("iris")  # list of values to loop over   uniq_species = unique(iris$Species)   # Loop  for (i in uniq_species) {    temp_plot = ggplot(data= subset(iris, Species == i)) +                    geom_point(size=3, aes(x=Petal.Length, y=Petal.Width )) +                   ggtitle(i)    ggsave(temp_plot, file=paste0("plot_", i,".png"), width = 14, height = 10, units = "cm") }