4 Summary

Phew – you made it! Well done!

Figure 11

During this week you’ve learned how to take a dataset that contains multiple possible groupings or subsets of data, and work with those groups to perform a variety of transformations.

In particular, you have learned how to:

• split the data contained in a dataframe into multiple groups based on the unique ‘key’ values in a single column, or unique combinations of values that appear across two or more columns
• an (summary) function to generate a single summary result for the group, and then combine these results to generate a summary report with as many rows as there were groups, one summary report row per group a function that would use the rows contained in each group as the basis for a filtering operation, returning rows from each group who’s group properties matched the filter conditions
• use a pivot table to generate a variety of summary reports.

You may not have thought of performing gymnastics with data before, but as you’ve seen, we can start to work our data quite hard if we need to get it into shape!