Writing Data
Overview
Teaching: 10 min
Exercises: 10 minQuestions
How can I save plots and data created in R?
Objectives
To be able to write out plots and data from R.
Saving plots
You can save a plot from within RStudio using the ‘Export’ button in the ‘Plot’ window. This will give you the option of saving as a .pdf or as .png, .jpg or other image formats.
Sometimes you will want to save plots without creating them in the ‘Plot’ window first. Perhaps you want to make a pdf document with multiple pages: each one a different plot, for example. Or perhaps you’re looping through multiple subsets of a file, plotting data from each subset, and you want to save each plot, but obviously can’t stop the loop to click ‘Export’ for each one.
In this case you can use a more flexible approach. The function
pdf
creates a new pdf device. You can control the size and resolution
using the arguments to this function.
pdf("Hclust_corplot_mtcars.pdf", width=5, height=5)
corrplot(cor_mtcars, order = "hclust", addrect = 3)
# You then have to make sure to turn off the pdf device!
dev.off()
Open up this document and have a look.
The commands jpeg
, png
etc. are used similarly to produce
documents in different formats.
Writing data
At some point, you’ll also want to write out data from R.
We can use the write.table
function for this, which is
very similar to read.table
from before.
Let’s create a data-cleaning script, for this analysis, we only want to focus on the gapminder data for Australia:
aust_subset <- gapminder[gapminder$country == "Australia",]
write.table(aust_subset,
file="gapminder-aus.csv",
sep=",",
row.names = FALSE,
quote = FALSE
)
or directly as a .csv file
aust_subset <- gapminder[gapminder$country == "Australia",]
write.csv(aust_subset,
file="gapminder-aus.csv",
row.names = FALSE,
quote = FALSE
)
Key Points
Save plots from RStudio using the ‘Export’ button.
Use
write.table
to save tabular data.