fixing bug rte-france#220

.gitignore

@@ -311,6 +311,7 @@ test_jorge/
 grid2op/data_test/l2rpn_neurips_2020_track1_with_alert.zip
 issue_208_res/
 test_issue_208.py
+test_issue_220.py
 
 # profiling files
 **.prof

CHANGELOG.rst

@@ -35,6 +35,8 @@ Change Log
   (**NB** we higly recommend importing the `Runner` like `from grid2op.Runner import Runner` though !)
 - [FIXED]: some bugs in the `action_space.get_all_unitary_redispatch` and `action_space.get_all_unitary_curtail`
 - [FIXED]: some bugs in the `GreedyAgent` and `TopologyGreedy`
+- [FIXED]: `Issue#220 <https://github.com/rte-france/Grid2Op/issues/220>`_ `flow_bus_matrix` did not took into
+  account disconnected powerlines, leading to impossibility to compute this matrix in some cases.
 - [ADDED] support for the "alarm operator" / "attention budget" feature
 - [ADDED] retrieval of the `max_step` (ie the maximum number of step that can be performed for the current episode)
   in the observation

grid2op/Observation/BaseObservation.py

@@ -1371,9 +1371,9 @@ def flow_bus_matrix(self, active_flow=True, as_csr_matrix=False):
             if self.shunts_data_available:
                 sh_vect = self._shunt_q
 
-        data = np.zeros(nb_bus + lor_bus.shape[0] + lex_bus.shape[0], dtype=dt_float)
         nb_lor = np.sum(lor_conn)
         nb_lex = np.sum(lex_conn)
+        data = np.zeros(nb_bus + nb_lor + nb_lex, dtype=dt_float)
 
         # if two generators / loads / storage unit are connected at the same bus
         # this is why i go with matrix product and sparse matrices

grid2op/tests/test_issue_220.py

@@ -0,0 +1,33 @@
+# Copyright (c) 2019-2020, RTE (https://www.rte-france.com)
+# See AUTHORS.txt
+# This Source Code Form is subject to the terms of the Mozilla Public License, version 2.0.
+# If a copy of the Mozilla Public License, version 2.0 was not distributed with this file,
+# you can obtain one at http://mozilla.org/MPL/2.0/.
+# SPDX-License-Identifier: MPL-2.0
+# This file is part of Grid2Op, Grid2Op a testbed platform to model sequential decision making in power systems.
+
+import unittest
+import warnings
+import numpy as np
+
+import grid2op
+
+
+class Issue220Tester(unittest.TestCase):
+    def setUp(self) -> None:
+        with warnings.catch_warnings():
+            warnings.filterwarnings("ignore")
+            self.env = grid2op.make('l2rpn_case14_sandbox', test=True)
+            self.env.seed(0)
+            self.env.reset()
+
+    def test_flow_bus_matrix(self):
+        obs = self.env.reset()
+        res, _ = obs.flow_bus_matrix()
+        assert res.shape == (14, 14)
+        action = self.env.action_space()
+        action.change_line_status = [9]
+        # two powerlines will be disconnected: powerline 9 (action) and powerline 13 ("cascading failure")
+        new_obs, reward, done, info = self.env.step(action)
+        res, _ = new_obs.flow_bus_matrix()
+        assert res.shape == (14, 14)