Simple lookup to insert values in an R data frame
lookup-tables, r
Solution
Since you don't care about the `market` column in `alldata`, you can first strip it off using and merge the columns in `alldata` and `zipcodes` based on the `zip` column using `merge`:
merge(alldata[, c("Case", "zip")], zipcodes, by="zip")
The `by` parameter specifies the key criteria, so if you have a compound key, you could do something like `by=c("zip", "otherfield")`.
Problem
This is a seemingly simple R question, but I don't see an exact answer here. I have a data frame (alldata) that looks like this: ``` Case zip market 1 44485 NA 2 44488 NA 3 43210 NA ``` There are over 3.5 million records. Then, I have a second data frame, 'zipcodes'. ``` market zip 1 44485 1 44486 1 44488 ... ... (100 zips in market 1) 2 43210 2 43211 ... ... (100 zips in market 2, etc.) ``` I want to find the correct value for alldata$market for each case based on alldata$zip matching the appropriate value in the zipcode data frame. I'm just looking for the right syntax, and assistance is much appreciated, as usual.