如何使用 get() 调用 R 函数中的变量？答案

【问题标题】：How to use get()to call on a variable in a function in R?如何使用 get() 调用 R 函数中的变量？
【发布时间】：2022-01-11 10:38:18
【问题描述】：

我正在尝试在函数中使用 get()。有时它有效，有时则无效。数据为：

ID<-c("001","002","003","004","005","006","007","008","009","010","NA","012","013")
Name<-c("Damon Bell","Royce Sellers",NA,"Cali Wall","Alan Marshall","Amari Santos","Evelyn Frye","Kierra Osborne","Mohammed Jenkins","Kara Beltran","Davon Harmon","Kaitlin Hammond","Jovany Newman")
Sex<-c("Male","Male","Male",NA,"Male","Male",NA,"Female","Male","Female","Male","Female","Male")
Age<-c(33,27,29,26,27,35,29,32,NA,25,34,29,26)
data<-data.frame(ID,Name,Sex,Age)

它适用于这样的一些代码：

FctPieChart <- function(data,Var){
  
  dVar <- data %>%
    filter(!is.na(get(Var))) %>%
    group_by(get(Var)) %>% #changes the name of the column to "`get(Var)`"
    summarise(Count = n()) %>%
    mutate(Total = sum(Count), Percentage = round((Count/Total),3))
}  
FctPieChart(data,"Sex")

它在其他一些代码中不起作用：

FctPieChart <- function(data,var){
  x <- data %>% 
    select(get(var))
  x
  
}  
FctPieChart(data,"Sex")

上面写着：

<error/simpleError>
object 'Sex' not found

有人知道为什么吗？

非常感谢您！

最好的问候，

斯蒂芬妮

【问题讨论】：

标签： r function variables get

【解决方案1】：

使用dplyr::select()，您不需要使用get()。而是使用select(var)

> FctPieChart <- function(data,var){
   x <- data %>% 
     select(var)
   x
 }  
> FctPieChart(data,"Sex")
      Sex
1    Male
2    Male
3    Male
4    <NA>
5    Male
6    Male
7    <NA>
8  Female
9    Male
10 Female
11   Male
12 Female
13   Male

【讨论】：