clean_names: correctly extract several variables from mgcv::s()

[etiennebacher]

Close #553

library(insight)
library(mgcv)
#> Loading required package: nlme
#> This is mgcv 1.8-40. For overview type 'help("mgcv-package")'.

set.seed(2) ## simulate some data... 
dat <- gamSim(1,n=400,dist="normal",scale=2)
#> Gu & Wahba 4 term additive model
b <- gam(y~x0+s(x1)+s(x2)+x3+s(x1,x2),data=dat)

find_smooth(b, flatten = TRUE) |> clean_names()
#> [1] "x1"     "x2"     "x1, x2"

^{Created on 2022-06-01 by the reprex package (v2.0.1)}

[etiennebacher]

Works with mgcv::s() but not with gam::s():

mgcv::s(Age)
#> $term
#> [1] "Age"
#> 
#> $bs.dim
#> [1] -1
#> 
#> $fixed
#> [1] FALSE
#> 
#> $dim
#> [1] 1
#> 
#> $p.order
#> [1] NA
#> 
#> $by
#> [1] "NA"
#> 
#> $label
#> [1] "s(Age)"
#> 
#> $xt
#> NULL
#> 
#> $id
#> NULL
#> 
#> $sp
#> NULL
#> 
#> attr(,"class")
#> [1] "tp.smooth.spec"
gam::s(Age)
#> Error in as.matrix(x): object 'Age' not found

^{Created on 2022-06-01 by the reprex package (v2.0.1)}

Using eval(parse) is probably the wrong approach because of this namespace conflict

[etiennebacher]

@IndrajeetPatil @strengejacke Unless you have changes to suggest, I think this is good to go:

library(insight)
library(mgcv)
#> Le chargement a nécessité le package : nlme
#> This is mgcv 1.8-40. For overview type 'help("mgcv-package")'.

dat <- gamSim(1,n=400,dist="normal",scale=2)
#> Gu & Wahba 4 term additive model
b <- gam(y~x0+s(x1)+s(x2)+x3+s(x1,x2),data=dat)

find_smooth(b, flatten = TRUE) |> clean_names()
#> [1] "x1"     "x2"     "x1, x2"

^{Created on 2022-06-07 by the reprex package (v2.0.1)}

[IndrajeetPatil]

LGTM, thanks!

[etiennebacher]

actually, I noticed some improvements to make, don't merge now