您可以使用函数
enquo
在函数调用中明确命名变量:
my_fun <- function(x, cat_var, num_var){
cat_var <- enquo(cat_var)
num_var <- enquo(num_var)
x %>%
group_by(!!cat_var) %>%
summarize(avg = mean(!!num_var), n = n(),
sd = sd(!!num_var), se = sd/sqrt(n))
}
这将为您提供:
> my_fun(df, var1, var2)
var1 avg n sd se
<fctr> <dbl> <int> <dbl> <dbl>
1 green 4.873617 7 0.7515280 0.2840509
2 red 5.337151 3 0.1383129 0.0798550
并且与您的示例输出匹配:
> df %>%
+ group_by(var1) %>%
+ summarize(avg=mean(var2), n=n(), sd=sd(var2), se=sd/sqrt(n))
# A tibble: 2 x 5
var1 avg n sd se
<fctr> <dbl> <int> <dbl> <dbl>
1 green 4.873617 7 0.7515280 0.2840509
2 red 5.337151 3 0.1383129 0.0798550
编辑:
楼主要求从函数中删除group_by
语句,以添加按多个变量分组的功能。在我看来,有两种方法可以解决这个问题。首先,您可以简单地删除group_by
语句,并将分组数据帧管道传递到函数中。该方法如下:
my_fun <- function(x, num_var){
num_var <- enquo(num_var)
x %>%
summarize(avg = mean(!!num_var), n = n(),
sd = sd(!!num_var), se = sd/sqrt(n))
}
df %>%
group_by(var1) %>%
my_fun(var2)
另一种实现方法是使用...
和quos
,以便函数能够捕获多个group_by
语句的参数。代码如下:
var1<-sample(c('red', 'green'), size=10, replace=T)
var2<-rnorm(10, mean=5, sd=1)
var3 <- sample(c("A", "B"), size = 10, replace = TRUE)
df<-data.frame(var1, var2, var3)
df %>%
group_by(var1, var3) %>%
my_fun(var2)
var1 var3 avg n sd se
<fctr> <fctr> <dbl> <int> <dbl> <dbl>
1 green A 5.248095 1 NaN NaN
2 green B 5.589881 2 0.7252621 0.5128378
3 red A 5.364265 2 0.5748759 0.4064986
4 red B 4.908226 5 1.1437186 0.5114865
my_fun2 <- function(x, num_var, ...){
group_var <- quos(...)
num_var <- enquo(num_var)
x %>%
group_by(!!!group_var) %>%
summarize(avg = mean(!!num_var), n = n(),
sd = sd(!!num_var), se = sd/sqrt(n))
}
df %>%
my_fun2(var2, var1, var3)
var1 var3 avg n sd se
<fctr> <fctr> <dbl> <int> <dbl> <dbl>
1 green A 5.248095 1 NaN NaN
2 green B 5.589881 2 0.7252621 0.5128378
3 red A 5.364265 2 0.5748759 0.4064986
4 red B 4.908226 5 1.1437186 0.5114865
code
mean_mpg = function(data, ..., x) { data %>% group_by_(.dots = lazyeval::lazy_dots(...)) %>% summarize(mean_mpg = ~mean(x)) }mtcars %>% mean_mpg(cyl, gear, mpg)code
它返回了错误信息“不是向量”。 - spindoctor