title: Giving nodes in an ox graph a color based on an attribute
body: <p>I have an ox graph, called G_map, with a geo data frame for nodes associated, as the following code.</p>
  <pre><code>G_nodes = ox.graph_to_gdfs(G_map,edges=False)
  </code></pre>
  <p>One of the G_nodes attributes is called 'osmid' and it's the ID of the node in open street map, so every single node has a different 'osmid'. My goal here is to plot the G_map graph giving certain nodes different colors, depending on the node ID, e.g., 'osmid'. For instance, if a node has a certain ID i would like for it to be red. I think I will have to use the osmnx function but I don't know how to do it exactly,</p>
  <pre><code>osmnx.plot.get_node_colors_by_attr()
  </code></pre>
  <p>I have also tried this:</p>
  <pre><code>node_c = ['b' if ('osmid'==25620516 or 'osmid'==25620570) else 'r' for idx in G_nodes(keys=True)]
  fig, ax = ox.plot_graph(G_map, node_color=node_c, node_edgecolor='w', node_size=30, node_zorder=3, edge_color=ec, edge_linewidth=3)
  </code></pre>
  <p>But i get an error saying:</p>
  <pre><code>TypeError: 'GeoDataFrame' object is not callable
  </code></pre>
  <p>If anyone could help me,
  Thank you!</p>