xcorduroy 0.0.1

Dask aware lightweight DEM utilities for Xarray

xCorduroy - Dask aware lightweight DEM utilities for Xarray

xcorduroy is a lightweight [dask, numpy, xarray and xproj] Xarray accessor for library for calculating hillshade, slope angle and aspects from DEMs.

** Warning: experimental**

Usage

Installation

uv add "xcorduroy @ git+https://github.com/norlandrhagen/corduroy"
# or 
pip install "git+https://github.com/norlandrhagen/corduroy"

Notebooks

An example notebook can be found in notebooks/DEM_example.ipynb

Example

import xarray as xr
import xcorduroy # This is needed for the .dem accessor
import xproj # This is needed for the .proj accessor

# Load a 2D Raster DEM
ds = xr.open_dataset("DEM.zarr", engine="zarr", chunks="auto")

# Make sure you have a crs registered
ds = ds.proj.assign_crs("EPSG:4326")

# Calculate hillshade. Note you can use the `dem` accessor.
hillshade = ds['dem'].dem.hillshade()
slope = ds['dem'].dem.slope()
aspect = ds['dem'].dem.aspect()


# Plotting
fig, axes = plt.subplots(2, 2, figsize=(12, 10), sharex=True, sharey=True)

ds['dem'].plot(ax=axes[0, 0], cmap='terrain', add_colorbar=True)
axes[0, 0].set_title("Input DEM")

slope.plot(ax=axes[0, 1], cmap='magma')
axes[0, 1].set_title("Slope")

aspect.plot(ax=axes[1, 0], cmap='twilight')
axes[1, 0].set_title("Aspect")

hillshade.plot(ax=axes[1, 1], cmap='gray')
axes[1, 1].set_title("Hillshade")

plt.tight_layout()

Methods

The three current methods implemented are .hillshade(), .slope() and .aspect(). The hillshade method is based off of the Horn, 1981 method. Details can be found in src/corduroy/DEM.py. They are inspired by similar methods in xdem and xarray-spatial. If you are looking for well-validated functions for scientific analysis, check out either of them. This library is a limited scope lightweight take on some of the methods, not a replacement.

Development

This project uses uv for dependency management, pytest and hypothesis for testing, ty for type-checking and ruff for linting.

Sync development environment

uv sync --all-extras

Run type checking

uv run ty check 

Run linter

uv run pre-commit run all-files

Run tests

uv run pytest tests/

What's in the name

Corduroy is a textured snow surface left by groomers that forms regular peaks and valleys.