
Problem –
You want to compare two vectors or you want to compare an entire vector against a scalar.
Solution –
The comparison operators (==, !=, <, >, <=, >=) can perform an element by element comparison of two vectors. They can also compare a vector’s element against a scalar.
R has two logical Values TRUE and FALSE. The comparison operators compare two values and return TRUE and FALSE depending upon the result of comparison.
> a <- 3
> a == pi
[1] FALSE
> a != pi
[1] TRUE
> a < pi
[1] TRUE
> a > pi
[1] FALSE
> a <= pi
[1] TRUE
> a >= pi
[1] FALSE
You can also do element by element comparison of two vectors.
> a <- c(5, 10, 15)
> b <- c(10, 10, 10)
> a == b
[1] FALSE TRUE FALSE
> a != b
[1] TRUE FALSE TRUE
> a < b
[1] TRUE FALSE FALSE
> a > b
[1] FALSE FALSE TRUE
> a <= b
[1] TRUE TRUE FALSE
> a >= b
[1] FALSE TRUE TRUE
You can also compare a vector with a scalar.
> a <- c(5, 10, 15)
> a == 5
[1] TRUE FALSE FALSE
> a != 5
[1] FALSE TRUE TRUE
After comparing two vectors, you may want to know whether any of the comparison were true or whether all the comparison were true. The any and all functions handle those tests. They both test a logical vector.
> a <- c(3, pi, 4)
> any(a == pi)
[1] TRUE
> all(a == 0)
[1] FALSE