Remove same columns from left_join

Question

I\'d like to merge two data frames by id, but they both have 2 of the same columns; therefore, when I merge i get new .x and .y column

Answer 1

You only need:

df <- left_join(df1, df2)

by = NULL, the default, join will do a natural join, using all variables with common names across the two tables. A message lists the variables so that you can check they're right

Output:

Joining by: c("id", "element", "day")
  id     value1 element day     value2
1  1 -0.6264538   TEST1  15 -0.8204684
2  2  0.1836433   TEST1  15  0.4874291
3  3 -0.8356286   TEST1  15  0.7383247
4  4  1.5952808   TEST1  15  0.5757814
5  5  0.3295078   TEST1  15 -0.3053884

It's worth pointing out the comment by thelatemail: "Joining on id is not the same as joining on id/element/day". However, in this specific example, because element and day are the same for all records in both tables we get the same result.

Original result

Data

set.seed(1)
df1 <- data.frame(id = seq(1,5), value1 = rnorm(5), element = "TEST1", day = 15) 
df2 <- data.frame(id = seq(1,5), value2 = rnorm(5), element = "TEST1", day = 15) 
df <- left_join(df1, df2, by = "id")

Output:

  id     value1 element.x day.x     value2 element.y day.y
1  1 -0.6264538     TEST1    15 -0.8204684     TEST1    15
2  2  0.1836433     TEST1    15  0.4874291     TEST1    15
3  3 -0.8356286     TEST1    15  0.7383247     TEST1    15
4  4  1.5952808     TEST1    15  0.5757814     TEST1    15
5  5  0.3295078     TEST1    15 -0.3053884     TEST1    15