R - subtraction operator example

The example below shows the usage of subtraction(-) operator in different scenarios.

Subtracting a scalar

If a scalar (single element atomic vector) is subtracted to a vector or a matrix, it is subtracted from each element of the vector or matrix.

#first operand
x1 <- 10
v1 <- c(10, 20, 30)
m1 <- matrix(c(10, 20, 30, 40, 50, 60), nrow=2)

#second operand
x2 <- 5

#subtracting a scalar from another
print(x1 - x2)
#subtracting a scalar from a vector
print(v1 - x2)
#subtracting a scalar from a matrix
cat("\n")
print(m1 - x2)

The output of the above code will be:

[1] 5
[1]  5 15 25

     [,1] [,2] [,3]
[1,]    5   25   45
[2,]   15   35   55

Subtracting a vector

When a vector is subtracted from another, their length should be same or length of longer vector should be multiple of length of shorter vector. Similarly, when a vector is subtracted from a matrix, the length of longer object should be multiple of length of shorter object.

Please note that, When a vector is subtracted from a matrix, elements are subtracted column-wise.

#first operand
x1 <- 10
v1 <- c(10, 20, 30)
m1 <- matrix(c(10, 20, 30, 40, 50, 60), nrow=2)

#second operand
v2 <- c(5, 6, 7)

#subtracting a vector from a scalar 
#(single element atomic vector) 
print(x1 - v2)
#subtracting a vector from another
print(v1 - v2)
#subtracting a vector from a matrix
cat("\n")
print(m1 - v2)

The output of the above code will be:

[1] 5 4 3
[1]  5 14 23

     [,1] [,2] [,3]
[1,]    5   23   44
[2,]   14   35   53

Subtracting a matrix

When a matrix is subtracted from another, their dimension should be same or dimension of bigger matrix should be multiple of dimension of smaller matrix.

#first operand
x1 <- 10
v1 <- c(10, 20, 30)
m1 <- matrix(c(10, 20, 30, 40, 50, 60), nrow=2)

#second operand
m2 <- matrix(c(1, 2, 3, 4, 5, 6), nrow=2)

#subtracting a matrix from a scalar 
#(single element atomic vector) 
print(x1 - m2)
#subtracting a matrix from a vector
cat("\n")
print(v1 - m2)
#subtracting a matrix from another
cat("\n")
print(m1 - m2)

The output of the above code will be:

     [,1] [,2] [,3]
[1,]    9    7    5
[2,]    8    6    4

     [,1] [,2] [,3]
[1,]    9   27   15
[2,]   18    6   24

     [,1] [,2] [,3]
[1,]    9   27   45
[2,]   18   36   54

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