R-decision making R conditional statements
R-decision making R conditional statements

R Decision Making

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Decision Making in R

In R programming, Decision Making statements also called conditional statement help to decide whether to execute a block of code or not, based on a condition. In this tutorial, we use decision making statements available in R language through examples.

The following are detailed of decision making statements in R.

  • R if statement
  • R if-else statement
  • R if-else-if statement
  • R switch statement

R If Statement

In If statement, a condition is evaluated using boolean expression TRUE/FALSE. If the result is TRUE, then a block of statements are executed.

Example R:

a <- 1
if (a == 1) {
  print("a is equal to 1.")
}
print("End of programme")

#output
[1] "a is equal to 1."
[1] "End of programme"

If the condition evaluates to FALSE, then if-block is not executed, and it will continue with the statements after the If statement.

Example R:

a <- 2
if (a == 1) {
  print("a is equal to 1.")
}
print("End of programme")

#output
[1] "End of programme"

R if-else statement

A condition is evaluated using boolean expression. If TRUE, then statements in if-block are execute, otherwise else-block statements are executed.

Example R:

a <- 2
if (a == 1) {
  print("a is 1.")
} else {
  print("a is not 1.")
}
print("End of program.")

#output:
[1] "a is not 1."
[1] "End of program."

R if-else-if statement

This is a chained if-else statement. It will scan and evaluate the conditions from top to down, whenever a condition evaluates to TRUE, corresponding block is executed, and the control exits from this if-else-if statement.

Example R:

a <- 5
if (a == 2) {
  print("a is 2.")
} else if (a == 5) {
  print("a is 5.")
} else if (a == 10) {
  print("a is 10.")
}
print("End of program.")

#output:
[1] "a is 5."
[1] "End of program."

R switch statement

In R Switch statement, an expression is evaluated and based on the result of matching index or value, a value is selected from a list of values.

Example R of matching index:

y <- 2
x <- switch(
  y,
  "Green",
  "Yellow",
  "Red",
  "Blue"
)
print(x)

#output:
[1] "Yellow"

Example R of matching value:

y <- "R"
x <- switch(
  y,
  "G"="Green",
  "Y"="Yellow",
  "R"="Red",
  "B"="Blue"
)
print(x)

#output:
[1] "Red"

Conclusion

In this R tutorial, we learned about decision making also called as conditional statements – If, If-Else, If-Else-If, and Switch.

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