Single-zone Grids can't be loaded from matfiles

[danielolsen]

🪲

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Bug summary

Trying to load a Grid from a matfile with a single zone causes a dimensional mismatch error.

Code for reproduction

A minimum code snippet required to reproduce the bug. Please make sure to minimize the
number of dependencies required.

>>> from powersimdata import Grid
>>> grid = Grid(source=PATH_TO_MATFILE, interconnect="ERCOT")
Loading bus
Loading plant
Loading heat_rate_curve
Loading gencost_before
Loading gencost_after
Loading branch
Loading sub
Loading bus2sub
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python39\lib\site-packages\powersimdata\input\grid.py", line 57, in __init__
    data = FromREISE(source)
  File "C:\Python39\lib\site-packages\powersimdata\input\scenario_grid.py", line 25, in __init__
    super().__init__()
  File "C:\Python39\lib\site-packages\powersimdata\input\abstract_grid.py", line 34, in __init__
    self._build_network()
  File "C:\Python39\lib\site-packages\powersimdata\input\scenario_grid.py", line 132, in _build_network
    self._read_network()
  File "C:\Python39\lib\site-packages\powersimdata\input\scenario_grid.py", line 102, in _read_network
    zone = pd.DataFrame(mpc.zone, columns=["zone_id", "zone_name"])
  File "C:\Python39\lib\site-packages\pandas\core\frame.py", line 672, in __init__
    mgr = ndarray_to_mgr(
  File "C:\Python39\lib\site-packages\pandas\core\internals\construction.py", line 324, in ndarray_to_mgr
    _check_values_indices_shape_match(values, index, columns)
  File "C:\Python39\lib\site-packages\pandas\core\internals\construction.py", line 393, in _check_values_indices_shape_match
    raise ValueError(f"Shape of passed values is {passed}, indices imply {implied}")
ValueError: Shape of passed values is (2, 1), indices imply (2, 2)

If we look at the matfile itself:

>>> from scipy.io import loadmat
>>> mpc = loadmat(PATH_TO_MATFILE, squeeze_me=True, struct_as_record=False)
>>> mpc["mdi"].mpc.zone
array([47, 'ERCOT'], dtype=object)

We can reproduce the same error with pandas and dummy data:

>>> import pandas as pd
>>> pd.DataFrame([1, 2], columns=[3, 4])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python39\lib\site-packages\pandas\core\frame.py", line 711, in __init__
    mgr = ndarray_to_mgr(
  File "C:\Python39\lib\site-packages\pandas\core\internals\construction.py", line 324, in ndarray_to_mgr
    _check_values_indices_shape_match(values, index, columns)
  File "C:\Python39\lib\site-packages\pandas\core\internals\construction.py", line 393, in _check_values_indices_shape_match
    raise ValueError(f"Shape of passed values is {passed}, indices imply {implied}")
ValueError: Shape of passed values is (2, 1), indices imply (2, 2)

Passing engine="REISE.jl" to the Grid constructor doesn't solve the problem.

Environment

Please specify your platform and versions of the relevant libraries you are using:

• Operating system: Windows
• PowerSimData revision: 8357023827885b936fb1aef758a09e82fdc93004
• Python version: 3.9.6