Extract Formula From lm with Coefficients (R)

Question

I have an lm object and want to get the formula extracted with coefficients. I know how to extract the formula without coefficients, and how to get the coefficients without

Answer 1

I figured out a versatile way of creating the model formula with coefficients using substitution. It's a lot more versatile than manually building a string with paste0.

e.g.

I have a model that already has the optimized coefficients:

> model
Nonlinear regression model
  model: players ~ pop * (decay^days_from_start) + ycept
   data: data
      pop     decay     ycept 
6.896e+06 2.633e-01 4.300e+05 
 residual sum-of-squares: 1.64e+08

Number of iterations to convergence: 12 
Achieved convergence tolerance: 1.49e-08

These were the coefficients:

> coef(model)
         pop        decay        ycept 
6.896421e+06 2.632545e-01 4.300453e+05 

Putting it all together:

> newFormula = as.formula(substituteDirect(formula(model), as.list(coef(model))))
> newFormula
players ~ 6896421.4399627 * (0.263254460933212^days_from_start) + 430045.26142703