stems.masking module

Helpers with data masks (clouds, qa/qc, etc)

References

• https://github.com/USGS-EROS/landsat-ldope-tools/blob/master/src/unpack_collection_bits.c

stems.masking.bitpack_to_coding(bitpack, bitinfo, fill=0, dtype=None)

Unpack a bipacked QA/QC band to some coding (e.g. CFMask)

Parameters

• bitpack (np.ndarray, dask.array.Array, or xr.DataArray) – Bitpacked data

• bitinfo (Dict[int, Sequence[Tuple[Int, Int, Int]]) – A dict mapping output codes to bit unpacking info(s) (offsets, widths, and values) for use in unpacking. Should be ordered in order of preference with values listed first possibly overwriting later ones

• fill (int, float, etc, optional) – Fill value to initialize array with (e.g., your “clear” value, since qa/qc bands usually indicate issues with data)

• dtype (np.dtype, optional) – Output NumPy datatype. If None, output will be same datatype as input bitpack

Returns

CFmask look-alike array

Return type

array

stems.masking.checkbit(data, offset, width=1, value=3)

Unpack a bit into True/False

Parameters

• data (np.ndarray, da.Array, xr.DataArray) – Bitpacked array data

• offset (int) – Bit offset

• width (int, optional) – Width of bitpacking (e.g., 1=>[0, 1], 2=>[0, 1, 2, 3])

• value (int, optional) – If width > 1, specify the value required to be True (e.g., 3 for ‘high’, 2 for ‘medium’, etc. in some codings)

Returns

True or False value of unpacked bit(s)

Return type

array-like, dtype=bool