how to use merge() to update a table in R

Question

I\'m trying to figure out how to use merge() to update a database.

Here is an example. Take for example the data frame foo

Answer 1

merge() only merges in new data. For instance, if you had a data set of average income for a few cities, and a separate data set of the populations of those cities, you would use merge() to merge in one set of data into the other.

Like apeescape said, replace() is probably what you want.