Checking for identical columns in a data frame in R

Question

Suppose you have a data frame called data with two identical columns:

A B
1 1
2 2
3 3
4 4

How can I check if these two columns are identica

Answer 1

You could use all():

> data <- data.frame(A=c(1,2,3,4), B=c(1,2,3,4))
> all(data$A == data$B)
[1] TRUE