r - 在 dplyr::mutate 中传递公式表达式

Question

有没有办法将公式表达式传递给 mutate 以创建新变量。

expression1 <- formula(ifelse(Var1 == 9, 0, Var1))

df <- data.frame(Var1 = sample(1:10, 10, replace = TRUE),
                 Var2 = sample(1:10, 10, replace = TRUE)) %>%
      mutate(new_var = expression1)

Answer 1

如果是字符串，那么我们可以解析它

library(dplyr)
expression1 <-  'ifelse(Var1 == 9, 0, Var1)'
df %>% 
   mutate(new_var = eval(rlang::parse_expr(expression1)))

-输出

#    Var1 Var2 new_var
#1     7    7       7
#2     5    7       5
#3     5    2       5
#4     4    6       4
#5     7    9       7
#6     9    3       0
#7     9    5       0
#8     2    9       2
#9     9    2       0
#10   10    9      10

数据

df <- data.frame(Var1 = sample(1:10, 10, replace = TRUE),
                 Var2 = sample(1:10, 10, replace = TRUE))