Add Column of Predicted Values to Data Frame with dplyr

Question

I have a data frame with a column of models and I am trying to add a column of predicted values to it. A minimal example is :

exampleTable <- data.frame(x          


        

Answer 1

Using the tidyverse:

library(dplyr)
library(purrr)
library(tidyr)
library(broom)

exampleTable <- data.frame(
  x = c(1:5, 1:5),
  y = c((1:5) + rnorm(5), 2*(5:1)),
  groups = rep(LETTERS[1:2], each = 5)
)

exampleTable %>% 
  group_by(groups) %>%
  nest() %>% 
  mutate(model = data %>% map(~lm(y ~ x, data = .))) %>% 
  mutate(Pred = map2(model, data, predict)) %>% 
  unnest(Pred, data)

# A tibble: 10 × 4
   groups      Pred     x          y
               
1       A  1.284185     1  0.9305908
2       A  1.909262     2  1.9598293
3       A  2.534339     3  3.2812002
4       A  3.159415     4  2.9283637
5       A  3.784492     5  3.5717085
6       B 10.000000     1 10.0000000
7       B  8.000000     2  8.0000000
8       B  6.000000     3  6.0000000
9       B  4.000000     4  4.0000000
10      B  2.000000     5  2.0000000