Nested for loop in R
A nested for-loop has a for-loop inside of another for-loop. For each of the iteration in the outer for-loop, the inner loop will be executed unless a final condition is met for the inner loop. Once an inner for-loop is executed for a particular outer iteration then the outer for-loop goes for the next iteration and now the inner loop will be executed for this iteration. This process repeats itself till the final condition is met for the outer for-loop. Nested for-loop can be visualized as iterating over integer coordinates one by one in a two-dimensional space. For example, printing
(0,0) (0,1) (0,2) (1,0) (1,1) (1,2) (2,0) (2,1) (2,2) (3,0) (3,1) (3,2)
Below is the syntax of nested for-loop in R.
Syntax:
for (element1 in sequence1) {
for(element2 in sequence2)
// body
}
Example 1: In the below program we are iterating over 0 to 3 in the outer loop and for each value in the outer for-loop, we are iterating over 0 to 3 in the inner for-loop.
R
# R program to illustrate the working of # nested for-loop # Iterating over 0 to 3 in the outer # for-loop for (x in 0:3){ # Iterating over 0 to 3 in the inner # for-loop for (y in 0:3) { # Print x and y print(paste("(", x, ",", y, ")")) } } |
Output:
Example 2: In the below program we are iterating over 1 to 5 in the outer loop and for each of the values in the outer for-loop, we are iterating over 1 to 5 in the inner for-loop and simultaneously printing the sum of the two values.
R
# R program to illustrate the working # of nested for-loop # Iterating over 1 to 5 in the outer # for-loop for(number1 in 1:5) { # Iterating over 1 to 5 in the inner # for-loop for(number2 in 1:5) { # Print the sum of number1 and number2 print(paste(number1, "+", number2, "=", number1 + number2)); } } |
Output:
How to Create a Nested For Loop in R?
A loop in a programming language is a sequence of instructions executed one after the other unless a final condition is met. Using loops is quite frequent in a program.