`ncol`

Basics

ncol is a function that returns the number of columns of a matrix, vector, array or data.frame.

Click to see solution

Let’s first take a look at our dataset.

# R built-in: Biochemical Oxygen Demand Dataset
BOD

  Time demand
1    1    8.3
2    2   10.3
3    3   19.0
4    4   16.0
5    5   15.6
6    7   19.8

Since we have 2 columns, we want ncol to return the value 2. Let’s try it out!

ncol(BOD)

[1] 2

Click to see solution

# Let's specify a matrix assigned to the variable x.
x <- matrix(c(1, 2, 3, 4), 1, 4)
ncol(x)

[1] 4