switch()

The switch() function provides a convenient way to select one of several alternatives based on a given value or condition. It is often used as an alternative to multiple if statements or nested if-else statements when there are a limited set of options to choose from.

Syntax

switch(expr, case1, case2, case3, ...)

In this pseudo-code:

• expr is the expression or value that needs to be evaluated.
• case1, case2, case3, and so on, are the possible cases or alternatives to be considered.

The expr value is compared with each case value sequentially, and when a match is found, the corresponding expression or value associated with that case is returned.

Examples

The following example illustrates a basic implementation of the switch() method:

day <- 3

weekday <- switch(day, "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")

print(weekday) # Output: Wednesday

In this example, the day variable is set to 3. The switch() function then compares the value of day with each case value. Since the third case matches, the corresponding value "Wednesday" is returned and assigned to the variable weekday.

The following example includes a default case:

month <- "Janvier"

season <- switch(
  month,
  "January"   = "Winter",
  "February"  = "Winter",
  "March"     = "Spring",
  "April"     = "Spring",
  "May"       = "Spring",
  "June"      = "Summer",
  "July"      = "Summer",
  "August"    = "Summer",
  "September" = "Autumn",
  "October"   = "Autumn",
  "November"  = "Autumn",
  "December"  = "Winter",
  "Unknown month"
)

print(season) # Output: Unknown month

In this scenario, the value of month does not match any of the specified cases, so the default case "Unknown month" is returned and assigned to the variable season.