pandas groupby.transform | Precision Python Throwback Part 2
Sign up for DUTC Weekly: https://mailchi.mp/dutc/ytweekly
LinkedIn: / do-n-t-use-this-code
Website: https://www.dontusethiscode.com/index...
Upcoming events: learning.dutc.io
Looking for training? Contact [email protected]
This is part of the Precision Python Throwback series.
• .groupby.transform is needed when you want to supply a user-defined function, because the existing .groupby methods are insufficient.
• The result of .groupby.transform will have the same indices as the original Series or DataFrame; groupby.transform is used when you want the transformation to preserve the original indexing
• Thus, the function passed to .groupby.transform must return a value that has the same shape as the group or can be broadcast to the shape of the group, the function must be able to operate on a column-by-column or row-by-row basis (depending on axis=); there is a fast-path if the operation can also apply the the entire DataFrame (but this fast-path is checked on the second group…)