flowmapviz

flowmapviz is a simple package for traffic flow visualization that was created as part of a bachelor's thesis. It includes functionality for rendering a single frame of a traffic flow map, that can be used for video rendering. This functionality is based on the matplotlib and osmnx packages.

The traffic map is rendered as a network graph where the color and width of edges are determined by the number of vehicles on the road segment.

flowmapviz is mainly used in FlowMapVideo for rendering videos of traffic flow based on the data from the Ruth simulator.

Installation

python pip install https://github.com/It4innovations/FlowMapFrame

Examples

As an example, you can run an interactive slider visualization to try the configurable parameters. To run the example, download input data from Zenodo and run the following command in the terminal:

flowmapviz-example map.graphml sim_data.pickle

Step-by-step guide

The following code shows how to use the package to render a single frame of a traffic flow map.

Importing the package:

import flowmapviz

Loading graph representing the map:

import osmnx as ox
g = ox.load_graphml("map.graphml")

Loading the preprocessed data saved from FlowMapVideo:

import pandas as pd
times_dic = pd.read_pickle("sim_data.pickle")

Rendering the base map:

from flowmapviz.zoom import plot_graph_with_zoom
import matplotlib.pyplot as plt
            
fig, ax = plt.subplots()
ax = plot_graph_with_zoom(g, ax)

Rendering the traffic flow:

Min and max density define the range of values for the color scale.
Min and max width density define the range of values for the width scale.
Default linewidth is the width of the line when the density is min density.
Width modifier is the width of the line when the density is max width density.
Road types by zoom is a boolean value that determines whether the road types are filtered by zoom level.
Hidden lines width is the width of the lines that are not "visible" at the current zoom level.

from flowmapviz.plot import plot_routes, WidthStyle
import matplotlib.pyplot as plt

one_frame_data =  list(times_dic.items())[0]
nodes_from = [s['node_from'] for s in one_frame_data]
nodes_to = [s['node_to'] for s in one_frame_data]
densities = [s['counts'] for s in one_frame_data]

plot_routes(g, ax, nodes_from, nodes_to, densities,
            min_density = 1, max_density = 10,
            min_width_density = 10, max_width_density = 50,
            default_linewidth = 3, width_modifier = 1,
            width_style = WidthStyle.BOXED,
            round_edges = True,
            roadtypes_by_zoom = False, hidden_lines_width = 1,
            plot = True)

plt.show()