如何将公式作为字符串使用?许多基本的R模型，例如lm()都接受字符串公式(否则，您始终可以使用formula()).在这种情况下，您可以使用gsub():

How about working with the formula as a string? Many base R models like lm() accept a string formulas (and you can always use formula() otherwise). In this case, you can use something like gsub():

f1 <- "y ~ x + z"
f2 <- "y ~ b*x + z"

gsub("x", "(x_part1 + x_part2)", f1)
#> [1] "y ~ (x_part1 + x_part2) + z"

gsub("x", "(x_part1 + x_part2)", f2)
#> [1] "y ~ b*(x_part1 + x_part2) + z"

例如，使用mtcars数据集，并说我们要用disp + hp(x_part1 + x_part2)替换mpg(x):

For example, with mtcars data set, and say we want to replace mpg (x) with disp + hp (x_part1 + x_part2):

f1 <- "qsec ~ mpg + cyl"
f2 <- "qsec ~ wt*mpg + cyl"

f1 <- gsub("mpg", "(disp + hp)", f1)
f2 <- gsub("mpg", "(disp + hp)", f2)

lm(f1, data = mtcars)
#> 
#> Call:
#> lm(formula = f1, data = mtcars)
#> 
#> Coefficients:
#> (Intercept)         disp           hp          cyl  
#>    22.04376      0.01017     -0.02074     -0.56571

lm(f2, data = mtcars)
#> 
#> Call:
#> lm(formula = f2, data = mtcars)
#> 
#> Coefficients:
#> (Intercept)           wt         disp           hp          cyl  
#>   20.421318     1.554904     0.026837    -0.056141    -0.876182  
#>     wt:disp        wt:hp  
#>   -0.006895     0.011126