Introduction to R — browser exercises

These short activities cover the base-R parts of day 1. Edit a cell and select Run Code. They execute in your browser and do not need RStudio.

Values and vectors

mass <- 47.5
age <- 122
mass_index <- mass / age

mass_index

molecules <- c("dna", "rna", "protein")
molecules2 <- c(molecules, "metabolites")

molecules2

Selecting values

weights <- c(21, 34, 39, 54, 55)

# Change 50 to try a different definition of a heavy rat.
heavy_weights <- weights[weights >= 50]
mean(heavy_weights)

molecules <- c("dna", "rna", "protein", "dna", "protein")
nucleic_acids <- c("dna", "rna")

molecules[molecules %in% nucleic_acids]

Missing values

heights <- c(2, 5, 6, 2, NA, 4)

mean(heights, na.rm = TRUE)

Small data frame

samples <- data.frame(
  sample = c("A", "B", "C"),
  expression = c(12.3, 9.8, 14.1)
)

samples
mean(samples$expression)