Pivot on column value

[rolyp]

Pivoting is a basic data reshaping operation familiar from spreadsheets and data frames. The idea is to treat the values in a column as a dimension, turning each value into an index. Often pivoting is combined with aggregation (e.g. summing or averaging another column and using the new dimenion to summarise). Non-aggregating variants either produce a nested structure where each of the new indices is mapped to a nested table, or combine pivoting with project to retain a flat structure. Variants on this kind of operation like this keeps cropping up in examples (see also the groupBy proposal below).

We should take a look at Pandas for an idea of how pivoting is provided in Python. In Pandas pivot reshapes without aggregation; pivot_table also provides aggregation.

See also:

• groupBy and sortBy #927
• Merge records with dictionaries #1076