OSMNX and Folium – Plotting and Isochrone on a Web Map

foliummatplotlibnetworkxopenstreetmappython

I am trying to plot an isochrone map like the one in this example onto a Folium Web Map.

I understand how to set up the colors for time/edges/nodes/polygons… I just don't understand how I could get any of that onto a Folium map…

I am having trouble understanding which object(s) to pass into the following two functions:

osmnx.plot.plot_route_folium() 
osmnx.plot.plot_graph_folium()

My code, currently, is simply following the above cited example, but I an stuck on how to incorporate Folium.

Best Answer

OSMnx does not have functionality to plot isochrones on a folium web map: see the documentation for plotting a graph with folium and for plotting a route with folium. Beyond that, you could write your own code to extend this functionality.

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[GIS] How to calculate latitude and longitude of a point in a static map

from what I understand, you have a single ungeoreferenced image, and you want to find the extent.

This can be done in QGIS

QGIS - Using Capture Coordinate

If this is an urban map with details in the corners, you can manually match up the corners using the Capture coordinate plugin.

start with an empty project
Install the OpenLayers plugin (this goes in the Web menu), and use this to show OSM for the region around your city
Install the "Capture coordinate" capture plugin, and bring up the Capture coordinate panel using the Vector > Coordinate Capture. You might want to set the sampling to EPSG:4326 to get traditional latitude, longitude coordinates
For two corner points on your png (diagonally opposite), look at the corner of your png and find its position in OSM, panning and zooming as required.
click on 'start capture', then click on the point corresponding to the corner of your image
once you have two diagonally opposite corners' coordinates, it's now simple maths to interpolate a pixel position to/from lat, lon

QGIS - Using georeferencing

This is a little more advanced, but will give you results if it's not possible to exactly pick out where the corners are (for example, if it's empty ground or in the sea)

start with empty project
use OpenLayers plugin to display OSM as before
install the Georeferencer plugin
start it up with Raster > Georeferencer
load in your png raster (first icon)
find some landmark on your png as close as possible to one corner- a building, for example, or a road junction
click on add point, and in the dialog check 'from map canvas'. If you have a mouse wheel you can pan with that. Click on the corresponding place in the OSM map.
repeat for the other 3 corners
see the GCP table? Those are your coordinates ('ground control points')
click on Transformation settings, and set up where you want to save the raster. You might want to change the crs to EPSG:4326 if you want lat,lon.
click on the Run icon (green arrow)
you'll now have a georeferenced tiff.

There's quite a good step-by-step guide here, although it's a bit out of date.

Now if you open this geotiff (add as a raster layer) you go into properties and you'll see your extent.

[GIS] Using Folium HeatMapWithTime Plugin

You can start importing your csv data (file_csv) in panda in a dataframe (df) with a code like :

import pandas as pd

df = pd.read_csv(file_csv)

(see réf. https://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_csv.html).

To convert a pandas dataframe (df) to a numpy ndarray, use this code:

df=df.values

df now becomes a numpy ndarray.

For the time, there's some documentation in the heat_map_with_time.py script. I have to look further (Ref. https://github.com/python-visualization/folium/blob/master/folium/plugins/heat_map_withtime.py)

Form the class infos:

index: Index giving the label (or timestamp) of the elements of data. Should have the same length as data, or is replaced by a simple count if not specified.

From what i understand, you need to have a time index dataframe the same size as the data dataframe (or array)

Best Answer

Related Solutions

[GIS] How to calculate latitude and longitude of a point in a static map

[GIS] Using Folium HeatMapWithTime Plugin

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