Extract restricted regression coefficients without using tidy - r

Question

I'm using the restriktor package to perform restricted regressions; however, at the same time I'm doing the restricted regressions by group using the dplyr. In order to extract the coefficients and have them formatted into a nice panel format, I use tidy and broom but the tidy packaged doesn't work on the restriktor so I'm not sure how to go about extracting the coefficients:
library(restriktor)
library(dplyr)
reg =
mtcars %>%
group_by(cyl) %>%
do(model = restriktor(lm(mpg ~ wt + hp, data =.), constraints = ' wt < -4 '))
I would like to have the b.restr which is the restricted model coefficients to be extracted for each group and formatted together into a panel normally I would use the following:
reg =
mtcars %>%
group_by(cyl) %>%
do({model = restriktor(lm(mpg ~ wt + hp, data =.), constraints = ' wt < -4 ') # create your model
data.frame(tidy(model), # get coefficient info
glance(model))})
But I get the following error:
Error: No tidy method for objects of class restriktor
All I want is to extract the following elements from the lists and put them altogether with their group identifier in one panel format:
reg[[2]][[1]][["b.restr"]]

Answer 1

Use group_modify (which is preferred over do now) with coef/as.list/as_tibble.
library(dplyr)
library(restriktor)
# coefficients and R2's or NAs if too few rows for restriktor
co <- function(fo, data) {
fm <- lm(fo, data)
coef_lm <- coef(fm)
min_rows <- length(coef_lm)
if (nrow(data) <= min_rows) NA * c(coef_lm, R2.org = NA, R2.reduced = NA)
else {
r <- restriktor(fm, constraints = ' wt < -4 ')
c(coef(r), R2.org = r$R2.org, R2.reduced = r$R2.reduced)
}
}
mtcars %>%
group_by(cyl) %>%
group_modify(~ {
.x %>%
co(mpg ~ wt + hp, .) %>%
as.list %>%
as_tibble
}) %>%
ungroup
giving:
tibble: 3 x 6
cyl `(Intercept)` wt hp R2.org R2.reduced
<dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1 4 45.8 -5.12 -0.0905 0.681 0.681
2 6 35.3 -4 -0.0256 0.589 0.667
3 8 33.9 -4 -0.0132 0.497 0.652