在 R 编程中将字符串转换为表达式 - parse()函数

R 语言中的parse()函数用于将字符类的对象转换为表达式类的对象。

Syntax: parse(text = character)

Parameters:
character: Object of character class

示例 1：

# R program to convert 
# character to expression
  
# Creating an object of character class
x <- "sin(pi / 2)"
  
# Class of object
class(x)
  
# Calling parse() Function
x1 <- parse(text = x)
  
# Class of parsed object
class(x1)

输出：

[1] "character"
[1] "expression"

示例 2：

# R program to convert 
# character to expression
  
# Creating an object of character class
x <- "2 ^ 3"
  
# Evaluating the value of object
eval(x)
  
# Calling parse() Function
x1 <- parse(text = x)
  
# Evaluating the value of object
eval(x1)

输出：

[1] "2^3"
[1] 8