fix typo in grid.py

GPRL/containers/grid.py

@@ -12,7 +12,7 @@ class FixGrid(Grid):# fix a bug in qdpy 0.1.2.1  with Deep grid (nb_items_per_bi
     def _init_grid(self) -> None:
         """Initialise the grid to correspond to the shape `self.shape`."""
         self._solutions = {x: [] for x in self._index_grid_iterator()}
-        self._nb_items_per_bin = np.zeros(self._shape, dtype=bool) #{x: 0 for x in self._index_grid_iterator()}
+        self._nb_items_per_bin = np.zeros(self._shape, dtype=int) #{x: 0 for x in self._index_grid_iterator()}
         self._fitness = {x: [] for x in self._index_grid_iterator()}
         self._features = {x: [] for x in self._index_grid_iterator()}
         self._quality = {x: None for x in self._index_grid_iterator()}
@@ -22,4 +22,4 @@ class FixGrid(Grid):# fix a bug in qdpy 0.1.2.1  with Deep grid (nb_items_per_bi
         self._nb_bins = reduce(operator.mul, self._shape)
         self.recentness_per_bin = {x: [] for x in self._index_grid_iterator()}
         self.history_recentness_per_bin = {x: [] for x in self._index_grid_iterator()}
-        self.activity_per_bin = np.zeros(self._shape, dtype=float)
\ No newline at end of file
+        self.activity_per_bin = np.zeros(self._shape, dtype=float)