Creating and Saving Graphs - R Base Graphs


Previously, we described the essentials of R programming and provided quick start guides for importing data into R.


Here, we’ll describe how to create and save graphs in R.


Pleleminary tasks

  1. Launch RStudio as described here: Running RStudio and setting up your working directory

  2. Prepare your data as described here: Best practices for preparing your data and save it in an external .txt tab or .csv files

  3. Import your data into R as described here: Fast reading of data from txt|csv files into R: readr package.

Here, we’ll use the R built-in mtcars data set.

# Create my_data
my_data <- mtcars
# Print the first 6 rows
head(my_data, 6)
##                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
## Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

Creating graphs

The R base function plot() can be used to create graphs.

plot(x = my_data$wt, y = my_data$mpg,
     pch = 16, frame = FALSE,
     xlab = "wt", ylab = "mpg", col = "#2E9FDF")

Saving graphs

If you are working with RStudio, the plot can be exported from menu in plot panel (lower right-pannel).

Plots panel –> Export –> Save as Image or Save as PDF

create and save plots

It’s also possible to save the graph using R codes as follow:


  1. Specify files to save your image using a function such as jpeg(), png(), svg() or pdf(). Additional argument indicating the width and the height of the image can be also used.
  2. Create the plot
  3. Close the file with dev.off()


Example:

# Open a pdf file
pdf("rplot.pdf") 
# 2. Create a plot
plot(x = my_data$wt, y = my_data$mpg,
     pch = 16, frame = FALSE,
     xlab = "wt", ylab = "mpg", col = "#2E9FDF")
# Close the pdf file
dev.off()

Or use this:

# 1. Open jpeg file
jpeg("rplot.jpg", width = 350, height = "350")
# 2. Create the plot
plot(x = my_data$wt, y = my_data$mpg,
     pch = 16, frame = FALSE,
     xlab = "wt", ylab = "mpg", col = "#2E9FDF")
# 3. Close the file
dev.off()

The R code above, saves the file in the current working directory.

File formats for exporting plots:

  • pdf(“rplot.pdf”): pdf file
  • png(“rplot.png”): png file
  • jpeg(“rplot.jpg”): jpeg file
  • postscript(“rplot.ps”): postscript file
  • bmp(“rplot.bmp”): bmp file
  • win.metafile(“rplot.wmf”): windows metafile

Infos

This analysis has been performed using R statistical software (ver. 3.2.4).


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