Switch Statement in R

A switch statement is a selection control mechanism which is used to choose one of the statements to execute from the multiple available statements, relative to the true condition. It is a conditional statement or a multi-way branch statement in R that can be used to avoid. Some of the important considerations related to the switch statement in R are:

• For character string as a condition for switch statement, the string is matched to the available cases.
• In cases of multiple matches, the first match element is executed.
• There is no default value to execute.

Methods:

The switch statement in R can use either of the two available methods to select a case to execute.

• Based on the Index:

The result of the expression is used as an index to decide the case when values like a character vector are used as cases, and the expression is evaluated to a number.

• Based on Matching Value:

The expression value is matched against case values if the cases have both case value and output value. For example: [“case1″=”value”]. The corresponding value of the matched case is displayed as the output.

Syntax:

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

Example 1:

var <- switch(  
4,  
"APPLE",  
"BOY",  
"CAT",     
"DOG", 
"ELEPHANT"  
)  
print(var)

Output:

[1] "DOG"

Example 2:

N1 = 2  
N2 = 3  
var = switch(  
    N1+N2,  
    "APPLE",  
    "BOY",  
    "CAT",     
    "DOG", 
    "ELEPHANT"   
)  
print (var)

Output:

[1] "ELEPHANT"

Example 3:

Alpha = "C"  
var = switch(  
    Alpha,  
    "A"="APPLE",  
    "B"="BOY",  
    "C"="CAT",     
    "D"="DOG", 
    "E"="ELEPHANT"   
)  
print (var)

Output:

[1] "CAT"

Example 4:

N1 = "3"  
N2 ="3"  
var = switch(  
    paste(N1,N2,sep=""),    
    "9"="APPLE",  
    "18"="BOY",  
    "22"="CAT",     
    "33"="DOG", 
    "21"="ELEPHANT"   
)  
print (var)

Output:

[1] "DOG"

Example 5:

N1 = "Y"  
N2 ="Z"  
var = switch(  
    paste(N1,N2,sep=""),    
    "XY"="APPLE",  
    "YZ"="BOY",  
    "PQ"="CAT",     
    "RS"="DOG", 
    "AB"="ELEPHANT"   
)  
print (var)

Output:

[1] "BOY"

Example 6:

choice = "SUB"  
N1 = 100  
N2 = 88  
Calculator = switch(  
    choice,  
    "ADD"=cat("Addition =",N1+N2,"\n"),  
    "SUB"=cat("Subtraction =",N1-N2,"\n"),  
    "DIV"=cat("Division =",N1/N2,"\n"),  
    "MUL"=cat("Product =",N1*N2,"\n")  
)  
 
print(Calculator)

Output:

Subtraction = 12
 
NULL