在地图循环中使用作为字符串的函数名称?
一些代码:
mymtcars <- mtcars %>% head %>% rownames_to_column('model') %>% group_by(vs) %>% nest
mymtcars
vs data
<dbl> <list>
1 0 <tibble [3 × 11]>
2 1 <tibble [3 × 11]>
我可以在这个列表列 df 上拟合线性模型,如下所示:
mymtcars %>%
+ mutate(mod = map(.x = data, ~ lm(.x$mpg ~ .x$cyl)))
# A tibble: 2 x 3
# Groups: vs [2]
vs data mod
<dbl> <list> <list>
1 0 <tibble [3 × 11]> <lm>
2 1 <tibble [3 × 11]> <lm>
如果我的函数名称是一个字段怎么办?
mymtcars2 <- mtcars %>% head %>% rownames_to_column('model') %>% group_by(vs) %>% nest %>% crossing(func = c('lm'))
> mymtcars2
# A tibble: 2 x 3
vs data func
<dbl> <list> <chr>
1 0 <tibble [3 × 11]> lm
2 1 <tibble [3 × 11]> lm
我试了一下:
mymtcars2 %>%
+ mutate(mod = map2(.x = data, .y = func, ~ .y(.x$mpg ~ .x$cyl)))
Error: Problem with `mutate()` input `mod`.
x could not find function ".y"
? Input `mod` is `map2(.x = data, .y = func, ~.y(.x$mpg ~ .x$cyl))`.
如何传递函数以在 map 中调用,然后在上面的块中调用它?
回答
可能match.fun在 map2 内部使用,如下所示:
models <- mymtcars2 %>%
mutate(mod = map2(.x = data, .y = func, ~ match.fun(.y)(.x$mpg ~ .x$cyl)))
输出:
[[1]]
Call:
match.fun(.y)(formula = .x$mpg ~ .x$cyl)
Coefficients:
(Intercept) .x$cyl
36.926733 -2.728218
[[2]]
Call:
match.fun(.y)(formula = .x$mpg ~ .x$cyl)
Coefficients:
(Intercept) .x$cyl
41.9400 -3.8025