knitr::opts_chunk$set( collapse = TRUE, comment = "#>" )
This vignette displays how to use nesting in
tidyfst. It has referred to
tidyrs vignette in https://tidyr.tidyverse.org/articles/nest.html. Now fist, we nest the "mtcars" data.frame by "cyl" column.
library(tidyfst) # nest by "cyl" column mtcars_nested <- mtcars %>% nest_dt(cyl) # you can use "cyl" too, very flexible # inspect the output data.table mtcars_nested
Now, we want to do a regression within the nested group "cyl". We'll use the famous
lapply to complete this:
mtcars_nested2 <- mtcars_nested %>% mutate_dt(model = lapply(ndt,function(df) lm(mpg ~ wt, data = df))) mtcars_nested2
We could see that the model is stored in the column "model". Now, we try to get the fitted value in the model.
mtcars_nested3 <- mtcars_nested2 %>% mutate_dt(model_predict = lapply(model, predict)) mtcars_nested3$model_predict
We could find that the "model_predict" is a list of numeric vectors. Let's try to unnest the target column "model_predict".
mtcars_nested3 %>% unnest_dt(model_predict)
This process would remove all the other list column automatically. For instance, in our case, the column "ndt" is removed.
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