Replace values in data frame based on other data frame in R

Question

In the below example, userids is my reference data frame and userdata is the data frame where the replacements should take place.

&         


        

Answer 1

Here's a possible solution, which will also work on datasets with multiple records of each ID, though we will need to coerce the ID and FRIENDID variables to character first:

> userdata$ID <- sapply(userdata$ID, function(x){gsub(x, userids[userids$USER==x, 2], x)})
> userdata$FRIENDID <- sapply(userdata$FRIENDID, function(x){gsub(x, userids[userids$USER==x, 2], x)})