Returns a new table containing the data from both tables. The rows are
combined based on the common values in the column(s) by. The option 'by' can
be a list of column names. When this is the case, merging is based on
multiple columns.
For example, the two tables below
==== ====
x y
==== ====
1 10
2 15
3 20
==== ====
==== ====
x u
==== ====
1 100
3 200
4 400
==== ====
when merged by column x, produce the following output:
===== ===== =====
x y u
===== ===== =====
1 10 100
2 15 None
3 20 200
4 None 400
===== ===== =====
Definition at line 3130 of file table.py.