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()