Install R and Run Your First Analysis

Confirm the installation

When R opens, it shows a startup message with the version number, followed by the > prompt where you type commands. You can also check the version by typing:

R.version.string

R responds with something like:

[1] "R version 4.6.1 (2026-06-24)"

Step 1: R as a calculator and variables

2 + 3 * 4
sqrt(144)

# Store a value in a variable with <-
hours <- 40
rate <- 18.50
hours * rate

Output:

[1] 14
[1] 12
[1] 740

Step 2: Vectors and statistics

A vector is a list of values, created with c(). Most R functions work on a whole vector at once:

scores <- c(78, 85, 92, 67, 88, 95, 73)

mean(scores)
median(scores)
max(scores)
sd(scores)        # standard deviation
scores[scores >= 85]   # only scores of 85 or higher

Output:

[1] 82.57143
[1] 85
[1] 95
[1] 10.27711
[1] 85 92 88 95

Step 3: Data frames

A data frame is R's version of a table or spreadsheet. R includes sample data sets; mtcars has data on 32 car models:

head(mtcars)            # first six rows
nrow(mtcars)            # number of rows
summary(mtcars$mpg)     # summary of the miles-per-gallon column
mean(mtcars$mpg[mtcars$cyl == 4])   # average mpg for 4-cylinder cars

The $ picks a column by name. The last line returns about 26.66 miles per gallon.

Step 4: A chart

R draws charts with one line of code. This opens a scatter plot in a new window:

plot(mtcars$wt, mtcars$mpg,
     main = "Car Weight vs. Fuel Economy",
     xlab = "Weight (1000 lbs)",
     ylab = "Miles per Gallon",
     pch = 19, col = "steelblue")

The plot shows that heavier cars tend to get fewer miles per gallon.

Step 5: Write a function and install a package

# A function that converts Fahrenheit to Celsius
to_celsius <- function(f) {
  (f - 32) * 5 / 9
}
to_celsius(c(32, 72, 212))

# Install a package from CRAN (only needed once), then load it
install.packages("praise")
library(praise)
praise()

The function returns 0.00000 22.22222 100.00000. When you install a package for the first time, R may ask you to choose a CRAN mirror (download site); choose 0-Cloud or one near you. praise() prints a random compliment, confirming the package works.