R If-else语句示例图解 _条件语句

在if语句中, 当条件为true时, 将执行内部代码。如果条件为假, 则将执行if块之外的代码。
还有另一种决策语句, 称为if-else语句。 if-else语句是if语句, 后跟else语句。当布尔表达式为false时, 将执行if-else语句, else语句。简而言之, 如果布尔表达式具有真值, 则执行if块, 否则执行else块。
R编程将任何非零和非空值都视为true, 如果该值是零或null, 则将它们视为false。
【R If-else语句示例图解】If-else语句的基本语法如下：

if(boolean_expression) {// statement(s) will be executed if the boolean expression is true.} else {// statement(s) will be executed if the boolean expression is false.}

流程图

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例子1

# local variable definitiona< - 100#checking boolean conditionif(a< 20){ # if the condition is true then print the following cat("a is less than 20\n")}else{ # if the condition is false then print the following cat("a is not less than 20\n")}cat("The value of a is", a)

输出

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例子2

x < - c("Hardwork", "is", "the", "key", "of", "success")if("key" %in% x) { print("key is found")} else {print("key is not found")}

输出

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例子3

a< - 100#checking boolean conditionif(a< 20){ cat("a is less than 20") if(a%%2==0){cat(" and an even number\n") } else{cat(" but not an even number\n") }}else{ cat("a is greater than 20") if(a%%2==0){cat(" and an even number\n") } else{cat(" but not an even number\n") }}

输出

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例子4

a< - 'u'if(a=='a'||a=='e'||a=='i'||a=='o'||a=='u'||a=='A'||a=='E'||a=='I'||a=='O'||a=='U'){ cat("character is a vowel\n") }else{ cat("character is a constant")}cat("character is =", a)}

输出

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例子5

a< - 'u'if(a=='a'||a=='e'||a=='i'||a=='o'||a=='u'||a=='A'||a=='E'||a=='I'||a=='O'||a=='U'){ cat("character is a vowel\n") }else{ cat("character is a constant")}cat("character is =", a)}

输出