R: Filling a column based on the value of another column in dataframe

Question

I want to map/join data values in DF2 to DF1

DF1 <- data.frame(match_col = c("apple", "apple", "apple", "banana", "banana","orange",))

DF2 <- data.frame(match_col = c("apple", "banana", "orange"), value = c(13,4,8))

I want the final data frame to look like:

apple | 13

apple | 13

apple | 13

banana | 4

orange | 8

Answer 1

You can use the merge() function to join two data based on matching column:

df_merged <- merge(DF1, DF2, by = "match_col")
df_merged
  match_col value
1     apple    13
2     apple    13
3     apple    13
4    banana     4
5    banana     4
6    orange     8