RF: Remove file-level nx imports in pipeline

Author: effigies

nipype/pipeline/engine/utils.py

@@ -21,7 +21,6 @@
 from functools import reduce
 
 import numpy as np
-import networkx as nx
 from future import standard_library
 
 from ... import logging, config, LooseVersion
@@ -55,12 +54,6 @@
 logger = logging.getLogger('nipype.workflow')
 PY3 = sys.version_info[0] > 2
 
-try:
-    dfs_preorder = nx.dfs_preorder
-except AttributeError:
-    dfs_preorder = nx.dfs_preorder_nodes
-    logger.debug('networkx 1.4 dev or higher detected')
-
 
 def _parameterization_dir(param):
     """
@@ -543,6 +536,7 @@ def _create_dot_graph(graph, show_connectinfo=False, simple_form=True):
     Ensures that edge info is pickleable.
     """
     logger.debug('creating dot graph')
+    import networkx as nx
     pklgraph = nx.DiGraph()
     for edge in graph.edges():
         data = graph.get_edge_data(*edge)
@@ -569,6 +563,7 @@ def _write_detailed_dot(graph, dotfilename):
         struct1:f2 -> struct3:here;
         }
     """
+    import networkx as nx
     text = ['digraph structs {', 'node [shape=record];']
     # write nodes
     edges = []
@@ -748,6 +743,7 @@ def evaluate_connect_function(function_source, args, first_arg):
 
 
 def get_levels(G):
+    import networkx as nx
     levels = {}
     for n in nx.topological_sort(G):
         levels[n] = 0
@@ -891,6 +887,7 @@ def _identity_nodes(graph, include_iterables):
     are included if and only if the include_iterables flag is set
     to True.
     """
+    import networkx as nx
     return [
         node for node in nx.topological_sort(graph)
         if isinstance(node.interface, IdentityInterface) and (
@@ -994,6 +991,12 @@ def generate_expanded_graph(graph_in):
     and b=[3,4] this procedure will generate a graph with sub-graphs
     parameterized as (a=1,b=3), (a=1,b=4), (a=2,b=3) and (a=2,b=4).
     """
+    import networkx as nx
+    try:
+        dfs_preorder = nx.dfs_preorder
+    except AttributeError:
+        dfs_preorder = nx.dfs_preorder_nodes
+
     logger.debug("PE: expanding iterables")
     graph_in = _remove_nonjoin_identity_nodes(graph_in, keep_iterables=True)
     # standardize the iterables as {(field, function)} dictionaries
@@ -1222,6 +1225,7 @@ def _iterable_nodes(graph_in):
 
     Return the iterable nodes list
     """
+    import networkx as nx
     nodes = nx.topological_sort(graph_in)
     inodes = [node for node in nodes if node.iterables is not None]
     inodes_no_src = [node for node in inodes if not node.itersource]
@@ -1349,6 +1353,7 @@ def export_graph(graph_in,
     Indicates whether to show the edge data on the graph. This
     makes the graph rather cluttered. default [False]
     """
+    import networkx as nx
     graph = deepcopy(graph_in)
     if use_execgraph:
         graph = generate_expanded_graph(graph)
@@ -1716,6 +1721,7 @@ def write_workflow_resources(graph, filename=None, append=None):
 def topological_sort(graph, depth_first=False):
     """Returns a depth first sorted order if depth_first is True
     """
+    import networkx as nx
     nodesort = list(nx.topological_sort(graph))
     if not depth_first:
         return nodesort, None

nipype/pipeline/engine/workflows.py

@@ -19,7 +19,6 @@
 import shutil
 
 import numpy as np
-import networkx as nx
 
 from ... import config, logging
 from ...utils.misc import str2bool
@@ -56,6 +55,7 @@ def __init__(self, name, base_dir=None):
             path to workflow storage
 
         """
+        import networkx as nx
         super(Workflow, self).__init__(name, base_dir)
         self._graph = nx.DiGraph()
 
@@ -366,6 +366,7 @@ def get_node(self, name):
     def list_node_names(self):
         """List names of all nodes in a workflow
         """
+        import networkx as nx
         outlist = []
         for node in nx.topological_sort(self._graph):
             if isinstance(node, Workflow):
@@ -482,6 +483,7 @@ def export(self,
            whether to include node and workflow config values
 
         """
+        import networkx as nx
         formats = ["python"]
         if format not in formats:
             raise ValueError('format must be one of: %s' % '|'.join(formats))
@@ -870,6 +872,7 @@ def _reset_hierarchy(self):
     def _generate_flatgraph(self):
         """Generate a graph containing only Nodes or MapNodes
         """
+        import networkx as nx
         logger.debug('expanding workflow: %s', self)
         nodes2remove = []
         if not nx.is_directed_acyclic_graph(self._graph):
@@ -942,6 +945,7 @@ def _get_dot(self,
                  level=0):
         """Create a dot file with connection info
         """
+        import networkx as nx
         if prefix is None:
             prefix = '  '
         if hierarchy is None: