Aggregation Without Grouping¶

1. You can aggregate all values in Columns of a DataFrame. Just use aggregation functions in select without groupBy, which is very similar to SQL syntax.

2. The aggregation functions all and any are available since Spark 3.0. However, they can be achieved using other aggregation functions such as sum

https://www.shanelynn.ie/summarising-aggregation-and-grouping-data-in-python-pandas/

Comment¶

1. The order of elements within each group are preserved (as the original order).

2. groupby works exactly the same on index if the index is named.

3. The order of columns in groupby matters if you want unstack the results later.

4. groupby works on columns too and it can group by some level of a MultiIndex.