How can I add a set of rows to each distinct observation in R-CodePudding

I am looking to automate a process in R that was previously done by hand and is very time consuming. I'd like to add a series of observations from one dataframe to each unique variable in another. An example using data will probably illustrate this better...

Table one contains a number of observations for each animal, this is the table where I will want to add a set of rows for each type of animal.

Animal	Colour	Temperament
Cat	Black	Calm
Dog	Beige	Anxious
Cat	White	Playful

Table two shows the rows that should be applied to each animal.

Colour	Temperament
Brown	Control
Beige	Control
White	Control

The final table should look something like:

Animal	Colour	Temperament
Cat	Black	Calm
Dog	Beige	Anxious
Cat	White	Playful
Cat	Brown	Control
Cat	Beige	Control
Cat	White	Control
Dog	Brown	Control
Dog	Beige	Control
Dog	White	Control

Would someone be able to point me in the right direction? Pref using tidyverse over base R (but not essential :) )

CodePudding user response：

1.We create an easy to use and reproducible example data

d1 <- data.frame(an = c("c", "d", "c"), 
                 cl = c("bl", "be", "wh"),
                 tm = c("cl", "an", "pl"))

d2 <- data.frame(cl = c("br", "be", "wh"),
                 tm = "cn")

2.Using expand_grid in combination with tidyr::full_join to expand the data.frame d1 to the desired form:

library(dplyr)
library(tidyr)

d1 %>% 
  full_join(expand_grid(d2, an = unique(d1$an)))

This returns:

  an cl tm
1  c bl cl
2  d be an
3  c wh pl
4  c br cn
5  d br cn
6  c be cn
7  d be cn
8  c wh cn
9  d wh cn