How to use R/Tutorials/Introduction

R is both a programming language, and a software environment for statistical computing.

Loading and plotting data with R

This tutorial demonstrates how to plot data loaded from files in R.

• Given the data file data.txt located at <path>:

1970    45    63
1980    52    59
1990    59    52
2000    63    45

• This data can easily be loaded into R using the following commands:

setwd("<path>")                # change working directory
data <- read.table("data.txt")  # load data

• Plotting can then be performed as follows:

# Setup empty plot window
plot(0, type = "n", main = "Plot Title", xlab = "X axis", ylab = "Y axis", xlim = c(1970,2000), ylim = c(0,100))
grid()                              # add grid
lines(data[,1], data[,2], lty = 1)  # draw first dataset
lines(data[,1], data[,3], lty = 2)  # draw second dataset
legend("topright", c("first dataset", "second dataset"), lty = c(1, 2) )

• Export of the plot to pdf is easilty performed by adding pdf("filename.pdf") prior to the plotting, and dev.off() after the plotting.
• Export to png can simmilarly be performed by calling png("filename.png") prior to the plotting, and dev.off() after the plotting. png("r_plot.png", width = 420, height = 340) will, for example yield the following figure:

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