Interview Q&A / Data Science

1. How does groupby work in pandas?

   groupby splits the rows into groups by key, applies a function such as sum or count to each group, and combines the results into a new object. Named aggregation lets you compute several summaries in one call.

   BeginnerQuick answer1 min read
2. What is the difference between agg and transform in a pandas groupby?

   agg returns one row per group, shrinking the data. transform returns a result with the same length as the original, repeating each group value on every row, so you can add it as a column and do row-level calculations like shares.

   IntermediateQuick answer1 min read