xrspatial.preview.preview#

xrspatial.preview.preview(agg, width=1000, height=None, method='mean', name='preview')[source]#

Downsample a raster to target pixel dimensions.

For dask-backed arrays, the operation is lazy: each chunk is reduced independently, so peak memory is bounded by the largest chunk plus the small output array. A 30 TB raster can be previewed at 1000x1000 with only a few MB of RAM.

Parameters:

  • agg (xr.DataArray) – Input raster (2D).

  • width (int, default 1000) – Target width in pixels.

  • height (int, optional) – Target height in pixels. If not provided, computed from width preserving the aspect ratio of agg.

  • method (str, default 'mean') –

    Downsampling method. One of:

    • 'mean': block averaging.

    • 'median': block median.

    • 'max': block maximum.

    • 'min': block minimum.

    • 'nearest': stride-based subsampling (fastest, no smoothing).

    • 'bilinear': bilinear interpolation via scipy.ndimage.zoom.

  • name (str, default 'preview') – Name for the output DataArray.

Returns:

Downsampled raster with updated coordinates.

Return type:

xr.DataArray