Question

I have a dataframe which holds an id and a result:

df <- data.frame(id=c(1,4,3,3,2,1),result=c(90,75,45,56,78,66))
df

I also have a key which holds a name for each id:

key <- data.frame(id=c(1:4),name=c("Jon","Fred","Jane","Jim"))
key 

How can I replace an id value in df with a name value from the key?

Thank you for your help.

Answer 1

> df[["id"]] <- key[ match(df[['id']], key[['id']] ) , 'name']
> df
    id result
1  Jon     90
2  Jim     75
3 Jane     45
4 Jane     56
5 Fred     78
6  Jon     66