在 dplyr 中使用字符串作为过滤器？

Question

Is there a way to use a string variable as the filter argument in dplyr? For example:

filter(iris,Sepal.Length > 6)

would be replaced with

string <- 'Sepal.Length > 6'
filter(iris,string)

Basically, I am looking for the entire filter string to be a variable as I am creating the filter string pragmatically. Thanks for any help.

Answer 1

If you want to filter with a string argument, you'll need to use filter_() instead of filter()

string <- 'Sepal.Length > 6'
filter_(iris, string)

Also note that it's recommended to use the *_() functions when programming.

Answer 2

This is the only way I have found that works in the new tidyval:

> s = "A<3"
> data.frame(A=1:10, B=1:10) %>% filter(eval(str2expression(s)))
  A B
1 1 1
2 2 2

However, I have not figured out how to do this with multiple conditions .