Saving Figures in RStudio

This is a simple tutorial on how to save a plot as an image file in R/RStudio.

Creating a figure

Suppose I have loaded the salamander into a variable called mander.

head(mander)

##        Date  Collector Year Season Site SVL Total_length    Sex
## 1  5-Sep-14 Sutherland 2014   Fall    A  36           72 female
## 2  4-Oct-14 Sutherland 2014   Fall    A  46           83 female
## 3  4-Oct-14 Sutherland 2014   Fall    A  42           89 female
## 4  4-Oct-14 Sutherland 2014   Fall    A  34           75 female
## 5  4-Oct-14 Sutherland 2014   Fall    A  37           80 female
## 6 18-Oct-14 Sutherland 2014   Fall    A  40           79 female

I’ll make a conditional boxplot of SVL by Site and Sex: (don’t worry if you don’t know what that means yet).

ggplot(mander, aes(x = Sex, y = SVL, fill = Site)) + 
  geom_boxplot() + 
  ggtitle("Salamander Snout to Vent Length")

My RStudio session will look something like this:

r session

Save the figure method 1

Notice that above the plot there is a button that says Export. Click there and choose whether you want to save the image as a .pdf or .png file.

Save the figure method 2

You can also save a figure directly using code in R. I prefer this method becuase you can more easily specify the options that you want to use for the image.

The image will be saved as the filename that you provide. The image will be saved in your current working directory.

The syntax is slightly different than what you’re used to. You have to use png() on the line before your plotting code. You have to place dev.off() on the line after your plotting code.

# This tells R to start an image file:
png(filename = "salamander_boxplot.png")

# These lines create the plot.
# You won't see the plot in the RStudio plot window.
ggplot(mander, aes(x = Sex, y = SVL, fill = Site)) + 
  geom_boxplot() + 
  ggtitle("Salamander Snout to Vent Length")

# This tells R to finish creating the image file and save it.
dev.off()

png() has lots of options (see the help entry). For example, you can specify the height and width of the output image (in pixels).

I’ll now have a file called salamander_boxplot.png in my current working directory.

The best way to learn is to try it!