windsaloft 0.0.2

Convert U/V raster to streamlines (geojson)

windsaloft

Convert a vectorial raster field into streamlines. The output is in a convenient GeoJSON format.

Installation

Install the latest version from the Python Package Index:

$ pip install windsaloft

Usage

To create the streamlines, a vectorial field is needed:

import numpy as np
import geojson
import pygrib
import windsaloft

grib = pygrib.open('data.grib2')

U/V Components

u = grib.select(shortName='u')[0].values
v = grib.select(shortName='v')[0].values

Convert GRIBs data to "standard" -180 to 180 extent global grids

u = np.roll(u, u.shape[1] // 2, axis=1)
v = np.roll(v, v.shape[1] // 2, axis=1)

Calculate streams

feature_collection = windsaloft.jet_streams(u, v, pixel_dist=5, min_value=10, smooth=2, zigzag_degrees=45)

Write output to a file

with open('streams.geojson', 'w') as fileout:
    geojson.dump(feature_collection, fileout, sort_keys=True, separators=(',', ':'))