pypolyline 0.2.4

Fast Google Polyline encoding and decoding using Rust FFI

Fast Google Polyline Encoding and Decoding

Installation

pip install pypolyline
Please use a recent (>= 8.1.2) version of pip.

Supported Python Versions

• Python 2.7
• Python 3.6
• Python 3.7

Supported Platforms

• Linux (manylinux1-compatible)
• OS X
• Windows 32-bit / 64-bit

Usage

Coordinates must be in (Longitude, Latitude) order

from pypolyline.util import encode_coordinates, decode_polyline

coords = [
            [52.64125, 23.70162],
            [52.64938, 23.70154],
            [52.64957, 23.68546],
            [52.64122, 23.68549],
            [52.64125, 23.70162]
         ]

# precision is 5 for Google Polyline, 6 for OSRM / Valhalla
polyline = encode_coordinates(coords, 5)
# polyline is 'ynh`IcftoCyq@Ne@ncBds@EEycB'
decoded_coords = decode_polyline(polyline, 5)

Attempts to decode an invalid Polyline will throw util.EncodingError
Attempts to encode invalid coordinates will throw util.DecodingError

Cython Module 🔥

If you're comfortable with a lack of built-in exceptions, you may use the compiled Cython version of the functions, giving a 3x speedup over the ctypes functions:

from pypolyline.cutil import encode_coordinates, decode_polyline

• Longitude errors will return strings beginning with Longitude error:
• Latitude errors will return strings beginning with Latitude error:
• Polyline errors will return [[nan, nan]]

How it Works

FFI and a Rust binary

Is It Fast

…Yes.
You can verify this by installing the polyline and cgpolyencode packages, then running benchmarks.py, a calibrated benchmark using cProfile.
On a 1.8 GHz Intel Core i7, The pure-Python test runs in ~21 s, the C++ (cgpolyencode.GPolyEncoder) test runs in around 600 ms, and The Rust + Cython benchmark runs in around 400 ms (33% faster).

License

MIT