Convert expression into function object.

expr_to_fun(expr_, order = NULL, vec_arg = FALSE)

Arguments

expr_: R expression.
order: desired order of function argument.
vec_arg: should the function take vector valued argument.

Examples


ee <- expression(b1 + (b0 - b1)*exp(-k*x) + b2*x)
ff <- expr_to_fun(ee)

ee <- expression(matrix(c(x1+x2, x1-x2, x1^2+x2^2, x1^3+x2^3), nrow=2))
ff <- expr_to_fun(ee)

ee <- expression(
  matrix(
    c(8 * x1 * (4 * x1^2 - 625 * x2^2 - 2 * x2
    - 1) + 9 * x1 - 20 * x2 * (x3 + 0.473809523809524 + exp(-x1 *
    x2)/20) * exp(-x1 * x2) - 3 * cos(x2 * x3) - 4.5,
    -20 * x1 * (x3 + 0.473809523809524 + exp(-x1 * x2)/20) * exp(-x1 * x2) + 3 * x3 *
    (x1 - cos(x2 * x3)/3 - 0.5) * sin(x2 * x3) + (-1250 * x2 - 2) * (4
    * x1^2 - 625 * x2^2 - 2 * x2 - 1),
    3 * x2 * (x1 - cos(x2 * x3)/3 -
    0.5) * sin(x2 * x3) + 400 * x3 + 189.52380952381 + 20 * exp(-x1 *
    x2)), nrow = 3))
f1 <- expr_to_fun(ee)
f2 <- expr_to_fun(ee, vec_arg=TRUE)
## Note: how long should parm be in f2?
formals(f2)$length_parm
#> [1] 3