Tips

Silencing status updates

To silence status updates to standard out, set silent=True:

import xagg as xa
xa.set_defaults(silent=True)

You can also silence a single operation using with:

# Calculate weightmaps without status updates
with xa.set_defaults(silent=True):
   weightmap = xa.pixel_overlaps(ds,gdf)

Note that the silent=True option in individual functions will be slowly deprecated over the next few versions in favor of using one of the two options above.

Saving weights file

If calculating weights from rasters is taking a substantial amount of time (e.g., your raster is very high resolution), you can save the calculated weights using:

# Create weightmap
weightmap = xa.pixel_overlaps(ds,gdf,silent=True)

# Save weightmap
weightmap.to_file('weights')

# Read weightmap
weightmap = xa.read_wm('weights')

# Continue as usual...
aggregated = xa.aggregate(ds,weightmap)

Note that weightmap.to_file(fn) creates and populates a separate _directory_ named fn to be able to store all the relevant components of the weightmap class, including shapefiles with the geometry of the input polygons, the dataframe with the pixel overlap data, the source grid, and any additional weight grids.

This feature is still slightly experimental, so please let us know your experiences!

Speed up overlap calculation

At the expense of increased memory usage, processing may be sped up using an alternate calculation method (impl='dot_product')

import xagg as xa
# Set dot_product as default backend implementation
xa.set_defaults(impl='dot_product')

Note that the impl=dot_product option in individual functions will be slowly deprecated over the next few versions in favor of using the option setting approach above (or using with xa.set_defaults(impl='dot_product'): ).

Create diagnostic figure to inspect raster/polygon overlaps

Once you have created a weightmap, the following code will create a diagnostic figure, showing a particular polygon (or groups of polygons) + the grid cells that overlap it, colored by the relative overlap of each grid cell with the polygon (NB: this currently only works if xa.pixel_overlaps() is run with subset_to_bbox=False, or using xa.subset_find() as detailed in Detailed Code Run):

# Querying polygon by column of the polygon `gdf`
weightmap.diag_fig({'name':'Alaska'},ds)

# Plotting the first polygon in the polygon `gdf`
weightmap.diag_fig(0,ds)