Functions for aggregating or combining data
Most data analysis projects require some reshaping of data. We may need to aggregate by group or combine data vertically or horizontally. We have to do similar tasks each time we prepare our data for this reshaping. We can routinize some of these tasks with functions, improving both the reliability of our code and our efficiency in getting the work done. We sometimes need to check for mismatches in merge-by columns before doing a merge, check for unexpected changes in values in panel data from one period to the next before aggregating, or concatenate a number of files at once and verify that data has been combined accurately.
These are just a few examples of the kind of data aggregation and combining tasks that might lend themselves to a more generalized coding solution. In this recipe, we define functions that can help with these tasks.
Getting ready
We will work with the COVID-19 daily data in this recipe. This data comprises...
