added line_plot option

Author: boothby

dwave_networkx/drawing/chimera_layout.py

@@ -20,7 +20,7 @@
 import networkx as nx
 from networkx import draw
 
-from dwave_networkx.drawing.qubit_layout import draw_qubit_graph, draw_embedding, draw_yield, normalize_size_and_aspect
+from dwave_networkx.drawing.qubit_layout import draw_qubit_graph, draw_embedding, draw_yield, normalize_size_and_aspect, draw_lineplot
 from dwave_networkx.generators.chimera import chimera_graph, find_chimera_indices, chimera_coordinates
 
 
@@ -151,7 +151,10 @@ def chimera_node_placer_2d(m, n, t, scale=1., center=None, dim=2, normalize_kwar
     """
     import numpy as np
 
-    center_pad = 1
+    line_plot = False if normalize_kwargs is None else normalize_kwargs.get('line_plot')
+
+    center_pad = 0 if line_plot else 1
+
     tile_center = t // 2
     tile_length = t + 2 + center_pad  # 2 for spacing between tiles
 
@@ -203,7 +206,18 @@ def _xy_coords(i, j, u, k):
         # convention for Chimera-lattice pictures is to invert the y-axis
         return np.hstack((xy * scale, paddims)) + center
 
-    return _xy_coords
+    if line_plot:
+        qubit_dx = np.hstack(([(t + 1)/2, 0], paddims)) * scale
+        qubit_dy = np.hstack(([0, (t + 1)/2], paddims)) * scale
+        def _line_coords(i, j, u, k):
+            xy = _xy_coords(i, j, u, k)
+            if u:
+                return np.vstack((xy - qubit_dx, xy + qubit_dx))
+            else:
+                return np.vstack((xy - qubit_dy, xy + qubit_dy))
+        return _line_coords
+    else:
+        return _xy_coords
 
 
 def draw_chimera(G, **kwargs):
@@ -226,6 +240,14 @@ def draw_chimera(G, **kwargs):
         form {edge: bias, ...}. Each bias should be numeric. Self-loop
         edges (i.e., :math:`i=j`) are treated as linear biases.
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the `pos` parameter which is not used by this
@@ -291,6 +313,14 @@ def draw_chimera_embedding(G, *args, **kwargs):
         the same vertices in G), and the drawing will display these overlaps as
         concentric circles.
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the `pos` parameter which is not used by this
@@ -327,6 +357,14 @@ def draw_chimera_yield(G, **kwargs):
     fault_style : string, optional (default='dashed')
         Edge fault line style (solid|dashed|dotted|dashdot)
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the `pos` parameter which is not used by this

dwave_networkx/drawing/pegasus_layout.py

@@ -19,7 +19,7 @@
 import networkx as nx
 from networkx import draw
 
-from dwave_networkx.drawing.qubit_layout import draw_qubit_graph, draw_embedding, draw_yield, normalize_size_and_aspect
+from dwave_networkx.drawing.qubit_layout import draw_qubit_graph, draw_embedding, draw_yield, normalize_size_and_aspect, draw_lineplot
 from dwave_networkx.generators.pegasus import pegasus_graph, pegasus_coordinates
 from dwave_networkx.drawing.chimera_layout import chimera_node_placer_2d
 
@@ -133,6 +133,11 @@ def pegasus_node_placer_2d(G, scale=1., center=None, dim=2, crosses=False, norma
     """
     import numpy as np
 
+    line_plot = False if normalize_kwargs is None else normalize_kwargs.get('line_plot')
+
+    if line_plot:
+        crosses = False
+
     m = G.graph['rows']
     h_offsets = G.graph["horizontal_offsets"]
     v_offsets = G.graph["vertical_offsets"]
@@ -180,7 +185,19 @@ def _xy_coords(u, w, k, z):
         # convention for Pegasus-lattice pictures is to invert the y-axis
         return np.hstack((xy * scale, paddims)) + center
 
-    return _xy_coords
+
+    if line_plot:
+        qubit_dx = np.hstack(([5.75, 0], paddims)) * scale
+        qubit_dy = np.hstack(([0, 5.75], paddims)) * scale
+        def _line_coords(u, w, k, z):
+            xy = _xy_coords(u, w, k, z)
+            if u:
+                return np.vstack((xy - qubit_dx, xy + qubit_dx))
+            else:
+                return np.vstack((xy - qubit_dy, xy + qubit_dy))
+        return _line_coords
+    else:
+        return _xy_coords
 
 
 def draw_pegasus(G, crosses=False, **kwargs):
@@ -207,7 +224,16 @@ def draw_pegasus(G, crosses=False, **kwargs):
     crosses: boolean (optional, default False)
         If True, :math:`K_{4,4}` subgraphs are shown in a cross
         rather than L configuration. Ignored if G is defined with
-        ``nice_coordinates=True``.
+        ``nice_coordinates=True`` or ``line_plot=True``.
+
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
 
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
@@ -277,6 +303,15 @@ def draw_pegasus_embedding(G, *args, crosses=False, **kwargs):
         If True, chains in ``emb`` may overlap (contain the same vertices
         in G), and these overlaps are displayed as concentric circles.
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the ``pos`` parameter, which is not used by this
@@ -315,7 +350,16 @@ def draw_pegasus_yield(G, crosses=False, **kwargs):
     crosses: boolean (optional, default False)
         If True, :math:`K_{4,4}` subgraphs are shown in a cross
         rather than L configuration. Ignored if G is defined with
-        ``nice_coordinates=True``.
+        ``nice_coordinates=True`` or ``line_plot=True``.
+
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
 
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,

dwave_networkx/drawing/qubit_layout.py

@@ -23,13 +23,16 @@
 from networkx import draw
 
 from dwave_networkx.drawing.distinguishable_colors import distinguishable_color_map
+from itertools import repeat, chain
+
+from numbers import Number
 
 __all__ = ['draw_qubit_graph']
 
 
 def draw_qubit_graph(G, layout, linear_biases={}, quadratic_biases={},
                      nodelist=None, edgelist=None, cmap=None, edge_cmap=None, vmin=None, vmax=None,
-                     edge_vmin=None, edge_vmax=None, midpoint=None,
+                     edge_vmin=None, edge_vmax=None, midpoint=None, line_plot=False,
                      **kwargs):
     """Draws graph G according to layout.
 
@@ -60,6 +63,16 @@ def draw_qubit_graph(G, layout, linear_biases={}, quadratic_biases={},
         be. If not provided, the colormap will default to the middle of
         min/max values provided.
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  Qubit line segments are given
+        twice the width of edges.  Layout should be a dict of the form
+        {node: ((x0, y0), (y0, x0)), ...} -- instead of coordinates, the nodes
+        are associated with endpoints of n-dimensional line segments.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the `pos` parameter which is not used by this
@@ -178,15 +191,21 @@ def node_color(v):
         if ax is None:
             ax = fig.add_axes([0.01, 0.01, 0.98, 0.98])
 
-    draw(G, layout, ax=ax, nodelist=nodelist, edgelist=edgelist,
-         cmap=cmap, edge_cmap=edge_cmap, vmin=vmin, vmax=vmax, edge_vmin=edge_vmin,
-         edge_vmax=edge_vmax,
-         **kwargs)
+    if line_plot:
+        draw_lineplot(G, layout, ax=ax, nodelist=nodelist, edgelist=edgelist,
+             cmap=cmap, edge_cmap=edge_cmap, vmin=vmin, vmax=vmax, edge_vmin=edge_vmin,
+             edge_vmax=edge_vmax,
+             **kwargs)
+    else:
+        draw(G, layout, ax=ax, nodelist=nodelist, edgelist=edgelist,
+             cmap=cmap, edge_cmap=edge_cmap, vmin=vmin, vmax=vmax, edge_vmin=edge_vmin,
+             edge_vmax=edge_vmax,
+             **kwargs)
 
 
 def draw_embedding(G, layout, emb, embedded_graph=None, interaction_edges=None,
                    chain_color=None, unused_color=(0.9,0.9,0.9,1.0), cmap=None,
-                   show_labels=False, overlapped_embedding=False, **kwargs):
+                   show_labels=False, overlapped_embedding=False, line_plot=False, **kwargs):
     """Draws an embedding onto the graph G, according to layout.
 
     If interaction_edges is not None, then only display the couplers in that
@@ -240,6 +259,16 @@ def draw_embedding(G, layout, emb, embedded_graph=None, interaction_edges=None,
         the same vertices in G), and the drawing will display these overlaps as
         concentric circles.
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  Qubit line segments are given
+        twice the width of edges.  Layout should be a dict of the form
+        {node: ((x0, y0), (y0, x0)), ...} -- instead of coordinates, the nodes
+        are associated with endpoints of n-dimensional line segments.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the `pos` parameter which is not used by this
@@ -252,6 +281,12 @@ def draw_embedding(G, layout, emb, embedded_graph=None, interaction_edges=None,
     except ImportError:
         raise ImportError("Matplotlib and numpy required for draw_chimera()")
 
+    if line_plot and show_labels:
+        raise NotImplementedError("line_plot style drawings do not currently support node labels")
+    
+    if line_plot and overlapped_embedding:
+        raise NotImplementedError("line_plot style drawings do not currently support overlapped embeddings")
+
     if nx.utils.is_string_like(unused_color):
         from matplotlib.colors import colorConverter
         alpha = kwargs.get('alpha', 1.0)
@@ -371,15 +406,25 @@ def show(p, q, u, v): return True
                 c = emb[v]
                 labels[list(c)[0]] = str(v)
 
-    # draw the background (unused) graph first
-    if unused_color is not None:
-        draw(G, layout, nodelist=nodelist, edgelist=background_edgelist,
-             node_color=node_color, edge_color=background_edge_color,
-             **kwargs)
+    if line_plot:
+        if unused_color is not None:
+            draw_lineplot(G, layout, nodelist=nodelist, edgelist=background_edgelist,
+                 node_color=node_color, edge_color=background_edge_color,
+                 **kwargs)
 
-    draw(G, layout, nodelist=nodelist, edgelist=edgelist,
-         node_color=node_color, edge_color=edge_color, labels=labels,
-         **kwargs)
+        draw_lineplot(G, layout, nodelist=nodelist, edgelist=edgelist,
+             node_color=node_color, edge_color=edge_color, z_offset = 10,
+             **kwargs)    
+    else:
+        # draw the background (unused) graph first
+        if unused_color is not None:
+            draw(G, layout, nodelist=nodelist, edgelist=background_edgelist,
+                 node_color=node_color, edge_color=background_edge_color,
+                 **kwargs)
+
+        draw(G, layout, nodelist=nodelist, edgelist=edgelist,
+             node_color=node_color, edge_color=edge_color, labels=labels,
+             **kwargs)
 
 
 def compute_bags(C, emb):
@@ -426,7 +471,7 @@ def unoverlapped_embedding(G, emb, interaction_edges):
 def draw_yield(G, layout, perfect_graph, unused_color=(0.9,0.9,0.9,1.0),
                fault_color=(1.0,0.0,0.0,1.0), fault_shape='o',
                fault_style='dashed', incident_fault_color=(1.0,0.8,0.8,1.0),
-               **kwargs):
+               line_plot = False, **kwargs):
     """Draws the given graph G with highlighted faults, according to layout.
 
     Parameters
@@ -461,6 +506,16 @@ def draw_yield(G, layout, perfect_graph, unused_color=(0.9,0.9,0.9,1.0),
     fault_style : string, optional (default='dashed')
         Edge fault line style (solid|dashed|dotted,dashdot)
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  Qubit line segments are given
+        twice the width of edges.  Layout should be a dict of the form
+        {node: ((x0, y0), (y0, x0)), ...} -- instead of coordinates, the nodes
+        are associated with endpoints of n-dimensional line segments.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the `pos` parameter which is not used by this
@@ -481,22 +536,36 @@ def draw_yield(G, layout, perfect_graph, unused_color=(0.9,0.9,0.9,1.0),
     incident_edgelist = edgeset(perfect_graph.edges) - edgeset(perfect_graph.subgraph(nodelist).edges)
     faults_edgelist = edgeset(perfect_graph.subgraph(nodelist).edges) - edgeset(G.edges)
 
-    faults_node_color = [fault_color for v in faults_nodelist]
-    faults_edge_color = [fault_color for e in faults_edgelist]
-    incident_edge_color = [incident_fault_color for e in incident_edgelist]
+    if line_plot:
+        if unused_color is not None:
+            node_color = [fault_color if v in faults_nodelist else unused_color for v in perfect_graph]
+            long_edgelist = list(edgeset(perfect_graph.edges) - incident_edgelist - faults_edgelist)
+        else:
+            node_color = []
+            long_edgelist = []
+        edge_color = [unused_color]*len(long_edgelist)
+        long_edgelist.extend(incident_edgelist)
+        edge_color.extend([incident_fault_color]*len(incident_edgelist))
+        long_edgelist.extend(faults_edgelist)
+        edge_color.extend([fault_color]*len(faults_edgelist))
+        draw_lineplot(perfect_graph, layout, edgelist=long_edgelist, node_color=node_color, edge_color=edge_color, **kwargs)
+    else:
+        faults_node_color = [fault_color for v in faults_nodelist]
+        faults_edge_color = [fault_color for e in faults_edgelist]
+        incident_edge_color = [incident_fault_color for e in incident_edgelist]
 
-    # Draw edges first, in the order (unused, incident, faults)
-    if unused_color is not None:
-        unused_edge_color = [unused_color for e in G.edges()]
-        nx.draw_networkx_edges(G, layout, edge_color=unused_edge_color, **kwargs)
-    nx.draw_networkx_edges(perfect_graph, layout, incident_edgelist, style=fault_style, edge_color=incident_edge_color, **kwargs)
-    nx.draw_networkx_edges(perfect_graph, layout, faults_edgelist, style=fault_style, edge_color=faults_edge_color, **kwargs)
+        # Draw edges first, in the order (unused, incident, faults)
+        if unused_color is not None:
+            unused_edge_color = [unused_color for e in G.edges()]
+            nx.draw_networkx_edges(G, layout, edge_color=unused_edge_color, **kwargs)
+        nx.draw_networkx_edges(perfect_graph, layout, incident_edgelist, style=fault_style, edge_color=incident_edge_color, **kwargs)
+        nx.draw_networkx_edges(perfect_graph, layout, faults_edgelist, style=fault_style, edge_color=faults_edge_color, **kwargs)
 
-    # Draw nodes second, in the order (unused, faults)
-    if unused_color is not None:
-        unused_node_color = [unused_color for e in G]
-        nx.draw_networkx_nodes(G, layout, node_color = unused_node_color, **kwargs)
-    nx.draw_networkx_nodes(perfect_graph, layout, faults_nodelist, node_shape=fault_shape, node_color=faults_node_color, **kwargs)
+        # Draw nodes second, in the order (unused, faults)
+        if unused_color is not None:
+            unused_node_color = [unused_color for e in G]
+            nx.draw_networkx_nodes(G, layout, node_color = unused_node_color, **kwargs)
+        nx.draw_networkx_nodes(perfect_graph, layout, faults_nodelist, node_shape=fault_shape, node_color=faults_node_color, **kwargs)
 
 
 def normalize_size_and_aspect(scale, node_scale, kwargs):
@@ -532,3 +601,162 @@ def normalize_size_and_aspect(scale, node_scale, kwargs):
         else:
             kwargs['width'] = 2*(fig_scale / scale)
 
+
+def draw_lineplot(G, layout, *, ax, node_size, width, nodelist=None,
+                  edgelist=None, node_color='blue', edge_color='black',
+                  cmap=None, vmin=None, vmax=None, edge_cmap=None,
+                  edge_vmin=None, edge_vmax=None, z_offset=0):
+    """Draws the graph G with line segments representing nodes
+
+    This function is meant to be a drop-in replacement for :func:`networkx.draw`
+    where nodes are associated with line segments (specified as 2x2 matrices
+    [[x0, y0], [x1, y1]]).  This function makes significant assumptions about
+    the edges of the graph G, that hold when G is a Chimera, Pegasus, or Zephyr
+    graph and the line segments are provided by :func:`chimera_layout`,
+    :func:`pegasus_layout` and :func:`zephyr_layout` respectively.  These graphs
+    have three classes of edges:
+
+        * internal edges between qubits whose line segments are perpendicular
+            and intersect at a point, which we draw with a circle located at the
+            point of intersection,
+        * external edges between qubits whose line segments are colinear, which
+            we draw as a line segment between the nearest endpoints, and
+        * odd edges between parallel qubits whose line segments are parallel and
+          overlap in a perpendicular projection, which we draw as a line segment
+          between the midpoints of the respective perpendicular projections
+
+    Parameters
+    ----------
+
+    G : networkx.Graph
+        A graph constructed by :func:`chimera_layout`, :func:`pegasus_layout, or
+        :func:`zephyr_layout`
+
+    pos : dict
+        A dictionary with nodes as keys and 2x2 matrices [[x0, y0], [x1, y1]]
+        representing the line segments of nodes.
+
+    ax : matplotlib.Axis
+        The matplotlib Axis object to draw the graph on.
+
+    node_size : float
+        The size (in area) of the circles used to depict internal edges.
+
+    width : float
+        The width of line segments associated with edges, and half the width of
+        line segments associated with nodes.
+
+    nodelist : iterable or None (default=None)
+        The set of nodes to draw.  If None, all nodes from G are drawn.
+
+    edgelist : iterable or None (default=None)
+        The set of edges to draw.  If both nodelist and edgelist are None, all
+        edges of G are drawn.  If edgelist is None, all edges from the subgraph
+        ``G.subgraph(nodelist)`` are drawn.
+
+    node_color : iterable or string (default='blue')
+        The sequence of colors to use in drawing nodes of G.  If node_color is
+        not a string, the colors are taken in the same order as nodelist, and
+        each color is either a float, a 3-tuple or 4-tuple of floats.
+
+    edge_color : iterable or string (default='black')
+        The sequence of colors to use in drawing edges of G.  If edge_color is
+        not a string, the colors are taken in the same order as edgelist, and
+        each color is either a float, a 3-tuple or 4-tuple of floats.
+
+    cmap : string or matplotlib.ColorMap or None (default=None)
+        A colormap to color nodes with.  Presumes that node_color is a sequence
+        of floats.
+
+    vmin : float or None (default=None)
+        Minimum value to use to use when normalizing node colors through cmap.
+
+    vmax : float or None (default=None)
+        Maximum value to use to use when normalizing node colors through cmap.
+
+    edge_cmap : string or matplotlib.ColorMap or None (default=None)
+        A colormap to color edges with.  Presumes that edge_color is a sequence
+        of floats.
+
+    edge_vmin : float or None (default=None)
+        Minimum value to use to use when normalizing edge colors through
+        edge_cmap
+
+    edge_vmax : float or None (default=None)
+        Maximum value to use to use when normalizing edge colors through
+        edge_cmap
+    
+    z_offset : int (default=0)
+        An offset to the zorder that various elements are drawn in.  Edge lines
+        are drawn with zorder=z_offset; horizontal node lines are drawn with
+        zorder=zoffset+1; vertical node lines are drawn with zorder=zoffset+2,
+        and edge circles are drawn with zorder=zoffset+3.  This parameter can be
+        used to layer line plots over or under eachother.
+    """
+
+    from networkx.drawing.nx_pylab import apply_alpha
+    import numpy as np
+    from matplotlib.collections import LineCollection, CircleCollection
+
+    if not isinstance(node_size, Number) or not isinstance(width, Number):
+        raise NotImplementedError("Varying node size and edge width per element in line plots is not implemented")
+
+    if edgelist is None:
+        if nodelist is not None:
+            edgelist = G.subgraph(nodelist).edges
+        else:
+            edgelist = G.edges
+    if nodelist is None:
+        nodelist = G
+
+    node_color = apply_alpha(node_color, 1, nodelist, cmap=cmap, vmin=vmin, vmax=vmax)
+    node_lines = np.array([layout[v] for v in nodelist], dtype='float')
+    vertical = np.array([abs(x0-x1) < abs(y0-y1) for (x0, y0), (x1, y1) in node_lines], dtype='bool')
+    if node_color.shape == (1, 4):
+        vcolor = hcolor = node_color
+    else:
+        vcolor = node_color[vertical]
+        hcolor = node_color[~vertical]
+    ax.add_collection(LineCollection(node_lines[~vertical], edgecolor=hcolor, linewidths=width, zorder=1+z_offset, capstyle='round'))
+    ax.add_collection(LineCollection(node_lines[vertical], edgecolor=vcolor, linewidths=width, zorder=2+z_offset, capstyle='round'))
+
+    if edge_color is not None and len(edgelist):
+        vertical = dict(zip(nodelist, map(int, vertical)))
+        as_line = np.full(len(edgelist), False, dtype='bool')
+        edge_data = np.empty((len(edgelist), 2, 2), dtype='float')
+        for i, (u, v) in enumerate(edgelist):
+            u0, u1 = layout[u]
+            v0, v1 = layout[v]
+            orientation = vertical[u]
+            if orientation == vertical[v]:
+                as_line[i] = True
+                if u0[orientation] > v1[orientation]:
+                    # external; v1 < u0
+                    edge_data[i] = v1, u0
+                elif v0[orientation] > u1[orientation]:
+                    # external; u1 < v0
+                    edge_data[i] = u1, v0
+                elif orientation:
+                    # odd, vertical
+                    ymean = (u0[1] + u1[1] + v0[1] + v1[1])/4
+                    edge_data[i] = (u0[0], ymean), (v0[0], ymean)
+                else:
+                    # odd, horizontal
+                    xmean = (u0[0] + u1[0] + v0[0] + v1[0])/4
+                    edge_data[i] = (xmean, u0[1]), (xmean, v0[1])
+            elif orientation:
+                # internal, u is vertical and v is horizontal
+                edge_data[i, 0] = u0[0], v0[1]
+            else:
+                # internal, v is vertical and u is horizontal
+                edge_data[i, 0] = v0[0], u0[1]
+
+        edge_color = apply_alpha(edge_color, 1, edgelist, cmap=edge_cmap, vmin=edge_vmin, vmax=edge_vmax)
+        if edge_color.shape == (1, 4):
+            edge_line_color = edge_spot_color = edge_color
+        else:
+            edge_line_color = edge_color[as_line]
+            edge_spot_color = edge_color[~as_line]
+        ax.add_collection(LineCollection(edge_data[as_line], edgecolor=edge_line_color, linewidths=width/2, zorder=z_offset))
+        ax.scatter(*edge_data[~as_line, 0].T, c=edge_spot_color, zorder=3+z_offset, s=node_size)
+    ax.autoscale_view()

dwave_networkx/drawing/zephyr_layout.py

@@ -19,7 +19,7 @@
 import networkx as nx
 from networkx import draw
 
-from dwave_networkx.drawing.qubit_layout import draw_qubit_graph, draw_embedding, draw_yield, normalize_size_and_aspect
+from dwave_networkx.drawing.qubit_layout import draw_qubit_graph, draw_embedding, draw_yield, normalize_size_and_aspect, draw_lineplot
 from dwave_networkx.generators.zephyr import zephyr_graph, zephyr_coordinates
 
 
@@ -123,6 +123,8 @@ def zephyr_node_placer_2d(G, scale=1., center=None, dim=2, normalize_kwargs = No
     """
     import numpy as np
 
+    line_plot = False if normalize_kwargs is None else normalize_kwargs.get('line_plot')
+
     m = G.graph['rows']
     tile_width = 2*G.graph["tile"]
 
@@ -157,7 +159,18 @@ def _xy_coords(u, w, k, j, z):
     if normalize_kwargs is not None:
         normalize_size_and_aspect(fabric_scale, 200, normalize_kwargs)
 
-    return _xy_coords
+    if line_plot:
+        qubit_dx = np.hstack(([tile_width - .25, 0], paddims)) * scale
+        qubit_dy = np.hstack(([0, tile_width - .25], paddims)) * scale
+        def _line_coords(u, w, k, j, z):
+            xy = _xy_coords(u, w, k, j, z)
+            if u:
+                return np.vstack((xy - qubit_dx, xy + qubit_dx))
+            else:
+                return np.vstack((xy - qubit_dy, xy + qubit_dy))
+        return _line_coords
+    else:
+        return _xy_coords
 
 def draw_zephyr(G, **kwargs):
     """Draws graph G in a Zephyr topology.
@@ -180,6 +193,14 @@ def draw_zephyr(G, **kwargs):
         edges in G and biases are numeric. Self-loop
         edges (i.e., :math:`i=j`) are treated as linear biases.
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the ``pos`` parameter, which is not used by this
@@ -198,9 +219,8 @@ def draw_zephyr(G, **kwargs):
     >>> plt.show()    # doctest: +SKIP
 
     """
-
-    draw_qubit_graph(G, zephyr_layout(G), **kwargs)
-
+    layout = zephyr_layout(G, normalize_kwargs = kwargs)
+    draw_qubit_graph(G, layout, **kwargs)
 
 def draw_zephyr_embedding(G, *args, **kwargs):
     """Draws an embedding onto Zephyr graph G.
@@ -244,13 +264,22 @@ def draw_zephyr_embedding(G, *args, **kwargs):
         If True, chains in ``emb`` may overlap (contain the same vertices
         in G), and these overlaps are displayed as concentric circles.
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the ``pos`` parameter, which is not used by this
        function. If ``linear_biases`` or ``quadratic_biases`` are provided,
        any provided ``node_color`` or ``edge_color`` arguments are ignored.
     """
-    draw_embedding(G, zephyr_layout(G), *args, **kwargs)
+    layout = zephyr_layout(G, normalize_kwargs = kwargs)
+    draw_embedding(G, layout, *args, **kwargs)
 
 def draw_zephyr_yield(G, **kwargs):
     """Draws the given graph G with highlighted faults, according to layout.
@@ -278,6 +307,14 @@ def draw_zephyr_yield(G, **kwargs):
     fault_style : string, optional (default='dashed')
         Edge fault line style (solid|dashed|dotted|dashdot)
 
+    line_plot : boolean (optional, default False)
+        If line_plot is True, then qubits are drawn as line segments, and edges
+        are drawn either as line segments between qubits, or as circles where
+        two qubits overlap.  In this drawing style, the interpretation the width
+        and node_size parameters (provided in kwargs) determines the area of the
+        circles, and line widths, respectively.  For more information, see
+        :func:`dwave_networkx.qubit_layout.draw_lineplot`.
+
     kwargs : optional keywords
        See networkx.draw_networkx() for a description of optional keywords,
        with the exception of the `pos` parameter which is not used by this
@@ -293,7 +330,6 @@ def draw_zephyr_yield(G, **kwargs):
         raise ValueError("Target zephyr graph needs to have columns, rows, \
         tile, and label attributes to be able to identify faulty qubits.")
 
-
     perfect_graph = zephyr_graph(m, t, coordinates=coordinates)
-
-    draw_yield(G, zephyr_layout(perfect_graph), perfect_graph, **kwargs)
+    layout = zephyr_layout(perfect_graph, normalize_kwargs = kwargs)
+    draw_yield(G, layout, perfect_graph, **kwargs)