This function extracts the formula from a `fixest`

estimation (obtained with `femlm`

,
`feols`

or `feglm`

). If the estimation was done with fixed-effects, they are added
in the formula after a pipe (“|”). If the estimation was done with a non
linear in parameters part, then this will be added in the formula in between `I()`

.

## Arguments

- x
An object of class

`fixest`

. Typically the result of a`femlm`

,`feols`

or`feglm`

estimation.- type
A character scalar. Default is

`type = "full"`

which gives back a formula containing the linear part of the model along with the fixed-effects (if any) and the IV part (if any). If`type = "linear"`

then only the linear formula is returned. If`type = "NL"`

then only the non linear in parameters part is returned.- ...
Not currently used.

## See also

See also the main estimation functions `femlm`

, `feols`

or `feglm`

.
`model.matrix.fixest`

, `update.fixest`

, `summary.fixest`

, `vcov.fixest`

.

## Examples

```
# simple estimation on iris data, using "Species" fixed-effects
res = femlm(Sepal.Length ~ Sepal.Width + Petal.Length +
Petal.Width | Species, iris)
# formula with the fixed-effect variable
formula(res)
#> Sepal.Length ~ Sepal.Width + Petal.Length + Petal.Width | Species
# linear part without the fixed-effects
formula(res, "linear")
#> Sepal.Length ~ Sepal.Width + Petal.Length + Petal.Width
#> <environment: 0x000001fef91280b0>
```