Plot a route along a networkx spatial graph.

    Parameters
    ----------
    G : networkx multidigraph
    route : list
        the route as a list of nodes
    bbox : tuple
        bounding box as north,south,east,west - if None will calculate from
        spatial extents of data. if passing a bbox, you probably also want to
        pass margin=0 to constrain it.
    fig_height : int
        matplotlib figure height in inches
    fig_width : int
        matplotlib figure width in inches
    margin : float
        relative margin around the figure
    axis_off : bool
        if True turn off the matplotlib axis
    bgcolor : string
        the background color of the figure and axis
    show : bool
        if True, show the figure
    save : bool
        if True, save the figure as an image file to disk
    close : bool
        close the figure (only if show equals False) to prevent display
    file_format : string
        the format of the file to save (e.g., 'jpg', 'png', 'svg')
    filename : string
        the name of the file if saving
    dpi : int
        the resolution of the image file if saving
    annotate : bool
        if True, annotate the nodes in the figure
    node_color : string
        the color of the nodes
    node_size : int
        the size of the nodes
    node_alpha : float
        the opacity of the nodes
    node_edgecolor : string
        the color of the node's marker's border
    node_zorder : int
        zorder to plot nodes, edges are always 2, so make node_zorder 1 to plot
        nodes beneath them or 3 to plot nodes atop them
    edge_color : string
        the color of the edges' lines
    edge_linewidth : float
        the width of the edges' lines
    edge_alpha : float
        the opacity of the edges' lines
    use_geom : bool
        if True, use the spatial geometry attribute of the edges to draw
        geographically accurate edges, rather than just lines straight from node
        to node
    origin_point : tuple
        optional, an origin (lat, lon) point to plot instead of the origin node
    destination_point : tuple
        optional, a destination (lat, lon) point to plot instead of the
        destination node
    route_color : string
        the color of the route
    route_linewidth : int
        the width of the route line
    route_alpha : float
        the opacity of the route line
    orig_dest_node_alpha : float
        the opacity of the origin and destination nodes
    orig_dest_node_size : int
        the size of the origin and destination nodes
    orig_dest_node_color : string
        the color of the origin and destination nodes
    orig_dest_point_color : string
        the color of the origin and destination points if being plotted instead
        of nodes

    Returns
    -------
    fig, ax : tuple

def plot_graph_route(G, route, bbox=None, fig_height=6, fig_width=None,
                     margin=0.02, bgcolor='w', axis_off=True, show=True,
                     save=False, close=True, file_format='png', filename='temp',
                     dpi=300, annotate=False, node_color='#999999',
                     node_size=15, node_alpha=1, node_edgecolor='none',
                     node_zorder=1, edge_color='#999999', edge_linewidth=1,
                     edge_alpha=1, use_geom=True, origin_point=None,
                     destination_point=None, route_color='r', route_linewidth=4,
                     route_alpha=0.5, orig_dest_node_alpha=0.5,
                     orig_dest_node_size=100, orig_dest_node_color='r',
                     orig_dest_point_color='b'):
    """
    Plot a route along a networkx spatial graph.

    Parameters
    ----------
    G : networkx multidigraph
    route : list
        the route as a list of nodes
    bbox : tuple
        bounding box as north,south,east,west - if None will calculate from
        spatial extents of data. if passing a bbox, you probably also want to
        pass margin=0 to constrain it.
    fig_height : int
        matplotlib figure height in inches
    fig_width : int
        matplotlib figure width in inches
    margin : float
        relative margin around the figure
    axis_off : bool
        if True turn off the matplotlib axis
    bgcolor : string
        the background color of the figure and axis
    show : bool
        if True, show the figure
    save : bool
        if True, save the figure as an image file to disk
    close : bool
        close the figure (only if show equals False) to prevent display
    file_format : string
        the format of the file to save (e.g., 'jpg', 'png', 'svg')
    filename : string
        the name of the file if saving
    dpi : int
        the resolution of the image file if saving
    annotate : bool
        if True, annotate the nodes in the figure
    node_color : string
        the color of the nodes
    node_size : int
        the size of the nodes
    node_alpha : float
        the opacity of the nodes
    node_edgecolor : string
        the color of the node's marker's border
    node_zorder : int
        zorder to plot nodes, edges are always 2, so make node_zorder 1 to plot
        nodes beneath them or 3 to plot nodes atop them
    edge_color : string
        the color of the edges' lines
    edge_linewidth : float
        the width of the edges' lines
    edge_alpha : float
        the opacity of the edges' lines
    use_geom : bool
        if True, use the spatial geometry attribute of the edges to draw
        geographically accurate edges, rather than just lines straight from node
        to node
    origin_point : tuple
        optional, an origin (lat, lon) point to plot instead of the origin node
    destination_point : tuple
        optional, a destination (lat, lon) point to plot instead of the
        destination node
    route_color : string
        the color of the route
    route_linewidth : int
        the width of the route line
    route_alpha : float
        the opacity of the route line
    orig_dest_node_alpha : float
        the opacity of the origin and destination nodes
    orig_dest_node_size : int
        the size of the origin and destination nodes
    orig_dest_node_color : string
        the color of the origin and destination nodes
    orig_dest_point_color : string
        the color of the origin and destination points if being plotted instead
        of nodes

    Returns
    -------
    fig, ax : tuple
    """

    # plot the graph but not the route
    fig, ax = plot_graph(G, bbox=bbox, fig_height=fig_height, fig_width=fig_width,
                         margin=margin, axis_off=axis_off, bgcolor=bgcolor,
                         show=False, save=False, close=False, filename=filename,
                         dpi=dpi, annotate=annotate, node_color=node_color,
                         node_size=node_size, node_alpha=node_alpha,
                         node_edgecolor=node_edgecolor, node_zorder=node_zorder,
                         edge_color=edge_color, edge_linewidth=edge_linewidth,
                         edge_alpha=edge_alpha, use_geom=use_geom)

    # the origin and destination nodes are the first and last nodes in the route
    origin_node = route[0]
    destination_node = route[-1]

    if origin_point is None or destination_point is None:
        # if caller didn't pass points, use the first and last node in route as
        # origin/destination
        origin_destination_lats = (G.nodes[origin_node]['y'], G.nodes[destination_node]['y'])
        origin_destination_lons = (G.nodes[origin_node]['x'], G.nodes[destination_node]['x'])
    else:
        # otherwise, use the passed points as origin/destination
        origin_destination_lats = (origin_point[0], destination_point[0])
        origin_destination_lons = (origin_point[1], destination_point[1])
        orig_dest_node_color = orig_dest_point_color

    # scatter the origin and destination points
    ax.scatter(origin_destination_lons, origin_destination_lats, s=orig_dest_node_size,
               c=orig_dest_node_color, alpha=orig_dest_node_alpha, edgecolor=node_edgecolor, zorder=4)

    # plot the route lines
    lines = node_list_to_coordinate_lines(G, route, use_geom)

    # add the lines to the axis as a linecollection
    lc = LineCollection(lines, colors=route_color, linewidths=route_linewidth, alpha=route_alpha, zorder=3)
    ax.add_collection(lc)

    # save and show the figure as specified
    fig, ax = save_and_show(fig, ax, save, show, close, filename, file_format, dpi, axis_off)
    return fig, ax