Lines on Tile Maps in Python

How to draw a line on tile-based maps in Python with Plotly.

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Lines on tile maps using Plotly Express¶

To draw a line on a map, you either can use px.line_map in Plotly Express, or go.Scattermap in Plotly Graph Objects. Here's an example of drawing a line on a tile-based map using Plotly Express.

In [1]:

import pandas as pd

us_cities = pd.read_csv("https://raw.githubusercontent.com/plotly/datasets/master/us-cities-top-1k.csv")
us_cities = us_cities.query("State in ['New York', 'Ohio']")

import plotly.express as px

fig = px.line_map(us_cities, lat="lat", lon="lon", color="State", zoom=3, height=300)

fig.update_layout(map_style="open-street-map", map_zoom=4, map_center_lat = 41,
    margin={"r":0,"t":0,"l":0,"b":0})

fig.show()

Lines on maps from GeoPandas¶

Given a GeoPandas geo-data frame with linestring or multilinestring features, one can extra point data and use px.line_map.

In [2]:

import plotly.express as px
import geopandas as gpd
import shapely.geometry
import numpy as np
import wget

# download a zipped shapefile
wget.download("https://plotly.github.io/datasets/ne_50m_rivers_lake_centerlines.zip")

# open a zipped shapefile with the zip:// pseudo-protocol
geo_df = gpd.read_file("zip://ne_50m_rivers_lake_centerlines.zip")

lats = []
lons = []
names = []

for feature, name in zip(geo_df.geometry, geo_df.name):
    if isinstance(feature, shapely.geometry.linestring.LineString):
        linestrings = [feature]
    elif isinstance(feature, shapely.geometry.multilinestring.MultiLineString):
        linestrings = feature.geoms
    else:
        continue
    for linestring in linestrings:
        x, y = linestring.xy
        lats = np.append(lats, y)
        lons = np.append(lons, x)
        names = np.append(names, [name]*len(y))
        lats = np.append(lats, None)
        lons = np.append(lons, None)
        names = np.append(names, None)

fig = px.line_map(lat=lats, lon=lons, hover_name=names,
                     map_style="open-street-map", zoom=1)
fig.show()

Lines on maps using `Scattermap` traces¶

This example uses go.Scattermap and sets the mode attribute to a combination of markers and line.

In [3]:

import plotly.graph_objects as go

fig = go.Figure(go.Scattermap(
    mode = "markers+lines",
    lon = [10, 20, 30],
    lat = [10, 20,30],
    marker = {'size': 10}))

fig.add_trace(go.Scattermap(
    mode = "markers+lines",
    lon = [-50, -60,40],
    lat = [30, 10, -20],
    marker = {'size': 10}))

fig.update_layout(
    margin ={'l':0,'t':0,'b':0,'r':0},
    map = {
        'center': {'lon': 10, 'lat': 10},
        'style': "open-street-map",
        'center': {'lon': -20, 'lat': -20},
        'zoom': 1})

fig.show()

Mapbox Maps¶

Mapbox traces are deprecated and may be removed in a future version of Plotly.py.

The earlier examples using px.line_map and go.Scattermap use Maplibre for rendering. These traces were introduced in Plotly.py 5.24 and are now the recommended way to draw lines on tile-based maps. There are also traces that use Mapbox: px.line_mapbox and go.Scattermapbox

To plot on Mapbox maps with Plotly you may need a Mapbox account and a public Mapbox Access Token. See our Mapbox Map Layers documentation for more information.

To draw a line on your map, you either can use px.line_mapbox in Plotly Express, or Scattermapbox traces. Below we show you how to draw a line on Mapbox using Plotly Express.

Here's an example of using Scattermapbox.

In [4]:

import plotly.graph_objects as go

fig = go.Figure(go.Scattermapbox(
    mode = "markers+lines",
    lon = [10, 20, 30],
    lat = [10, 20,30],
    marker = {'size': 10}))

fig.add_trace(go.Scattermapbox(
    mode = "markers+lines",
    lon = [-50, -60,40],
    lat = [30, 10, -20],
    marker = {'size': 10}))

fig.update_layout(
    margin ={'l':0,'t':0,'b':0,'r':0},
    mapbox = {
        'center': {'lon': 10, 'lat': 10},
        'style': "open-street-map",
        'center': {'lon': -20, 'lat': -20},
        'zoom': 1})

fig.show()

Reference¶

See function reference for px.line_map or https://plotly.com/python/reference/scattermap/ for more information about the attributes available.

For Mapbox-based tile maps, see function reference for px.line_mapbox or https://plotly.com/python/reference/scattermapbox/.

What About Dash?¶

Dash is an open-source framework for building analytical applications, with no Javascript required, and it is tightly integrated with the Plotly graphing library.

Learn about how to install Dash at https://dash.plot.ly/installation.

Everywhere in this page that you see fig.show(), you can display the same figure in a Dash application by passing it to the figure argument of the Graph component from the built-in dash_core_components package like this:

import plotly.graph_objects as go # or plotly.express as px
fig = go.Figure() # or any Plotly Express function e.g. px.bar(...)
# fig.add_trace( ... )
# fig.update_layout( ... )

from dash import Dash, dcc, html

app = Dash()
app.layout = html.Div([
    dcc.Graph(figure=fig)
])

app.run_server(debug=True, use_reloader=False)  # Turn off reloader if inside Jupyter