Use isort with pre-commit to enforce import guidelines (#5659)

* Add isort to pre-commit

* Run isort on all python files (except __init__.py ones)

6 files changed, 23 insertions, 17 deletions

diff --git a/networkx/drawing/nx_agraph.py b/networkx/drawing/nx_agraph.py
index a2350ef2..dc636b4b 100644
--- a/networkx/drawing/nx_agraph.py
+++ b/networkx/drawing/nx_agraph.py
@@ -19,6 +19,7 @@ See Also
 """
 import os
 import tempfile
+
 import networkx as nx
 
 __all__ = [
@@ -469,9 +470,10 @@ def display_pygraphviz(graph, path, format=None, prog=None, args=""):
     calls if you experience problems.
 
     """
-    from PIL import Image
     import warnings
 
+    from PIL import Image
+
     warnings.warn(
         "display_pygraphviz is deprecated and will be removed in NetworkX 3.0. "
         "To view a graph G using pygraphviz, use nx.nx_agraph.view_pygraphviz(G). "
diff --git a/networkx/drawing/nx_pydot.py b/networkx/drawing/nx_pydot.py
index 0aa6612a..7df22b9c 100644
--- a/networkx/drawing/nx_pydot.py
+++ b/networkx/drawing/nx_pydot.py
@@ -20,8 +20,9 @@ See Also
  - DOT Language:  http://www.graphviz.org/doc/info/lang.html
 """
 from locale import getpreferredencoding
-from networkx.utils import open_file
+
 import networkx as nx
+from networkx.utils import open_file
 
 __all__ = [
     "write_dot",
diff --git a/networkx/drawing/nx_pylab.py b/networkx/drawing/nx_pylab.py
index 6c5cb804..18ce0845 100644
--- a/networkx/drawing/nx_pylab.py
+++ b/networkx/drawing/nx_pylab.py
@@ -17,15 +17,16 @@ See Also
  - :obj:`matplotlib.patches.FancyArrowPatch`
 """
 from numbers import Number
+
 import networkx as nx
 from networkx.drawing.layout import (
-    shell_layout,
     circular_layout,
     kamada_kawai_layout,
+    planar_layout,
+    random_layout,
+    shell_layout,
     spectral_layout,
     spring_layout,
-    random_layout,
-    planar_layout,
 )
 
 __all__ = [
@@ -405,10 +406,11 @@ def draw_networkx_nodes(
     draw_networkx_edge_labels
     """
     from collections.abc import Iterable
-    import numpy as np
+
     import matplotlib as mpl
     import matplotlib.collections  # call as mpl.collections
     import matplotlib.pyplot as plt
+    import numpy as np
 
     if ax is None:
         ax = plt.gca()
@@ -636,13 +638,13 @@ def draw_networkx_edges(
     draw_networkx_edge_labels
 
     """
-    import numpy as np
     import matplotlib as mpl
+    import matplotlib.collections  # call as mpl.collections
     import matplotlib.colors  # call as mpl.colors
     import matplotlib.patches  # call as mpl.patches
-    import matplotlib.collections  # call as mpl.collections
     import matplotlib.path  # call as mpl.path
     import matplotlib.pyplot as plt
+    import numpy as np
 
     # The default behavior is to use LineCollection to draw edges for
     # undirected graphs (for performance reasons) and use FancyArrowPatches
@@ -1475,11 +1477,12 @@ def apply_alpha(colors, alpha, elem_list, cmap=None, vmin=None, vmax=None):
         Array containing RGBA format values for each of the node colours.
 
     """
-    from itertools import islice, cycle
-    import numpy as np
+    from itertools import cycle, islice
+
     import matplotlib as mpl
-    import matplotlib.colors  # call as mpl.colors
     import matplotlib.cm  # call as mpl.cm
+    import matplotlib.colors  # call as mpl.colors
+    import numpy as np
 
     # If we have been provided with a list of numbers as long as elem_list,
     # apply the color mapping.
diff --git a/networkx/drawing/tests/test_agraph.py b/networkx/drawing/tests/test_agraph.py
index 33e77c36..c99d29fb 100644
--- a/networkx/drawing/tests/test_agraph.py
+++ b/networkx/drawing/tests/test_agraph.py
@@ -1,14 +1,14 @@
 """Unit tests for PyGraphviz interface."""
 import os
 import tempfile
+
 import pytest
 
 pygraphviz = pytest.importorskip("pygraphviz")
 
 
-from networkx.utils import nodes_equal, edges_equal, graphs_equal
-
 import networkx as nx
+from networkx.utils import edges_equal, graphs_equal, nodes_equal
 
 
 class TestAGraph:
diff --git a/networkx/drawing/tests/test_layout.py b/networkx/drawing/tests/test_layout.py
index 2626c70a..f2fd90e7 100644
--- a/networkx/drawing/tests/test_layout.py
+++ b/networkx/drawing/tests/test_layout.py
@@ -1,8 +1,8 @@
 """Unit tests for layout functions."""
-import networkx as nx
-
 import pytest
 
+import networkx as nx
+
 np = pytest.importorskip("numpy")
 pytest.importorskip("scipy")
 
diff --git a/networkx/drawing/tests/test_pylab.py b/networkx/drawing/tests/test_pylab.py
index c5189fd6..33ce4e85 100644
--- a/networkx/drawing/tests/test_pylab.py
+++ b/networkx/drawing/tests/test_pylab.py
@@ -1,6 +1,6 @@
 """Unit tests for matplotlib drawing functions."""
-import os
 import itertools
+import os
 
 import pytest
 
@@ -641,8 +641,8 @@ def test_draw_edges_toggling_with_arrows_kwarg():
       - ``arrows=True`` -> FancyArrowPatches
       - ``arrows=False`` -> LineCollection
     """
-    import matplotlib.patches
     import matplotlib.collections
+    import matplotlib.patches
 
     UG = nx.path_graph(3)
     DG = nx.path_graph(3, create_using=nx.DiGraph)