cf.Field.set_quantize_on_write

Field.set_quantize_on_write(quantization=None, algorithm=None, quantization_nsd=None, quantization_nsb=None)

Set a quantize-on-write instruction.

Quantization eliminates false precision, usually by rounding the least significant bits of floating-point mantissas to zeros, so that a subsequent compression on disk is more efficient.

The existence of a quantize-on-write instruction does not mean that the data in memory has been quantized, rather it means that if the data is written to a netCDF dataset with cf.write, then quantization will be applied to the data in the netCDF dataset on disk, leaving the data in memory unchanged.

An existing quantization-on-write instruction is removed prior to the new setting.

Added in version (cfdm): 1.12.2.0

See also

get_quantize_on_write, del_quantize_on_write, _set_quantization

Parameters:

quantization: Quantization or None, optional

The quantize-on-write instructions. By default, or if None, a Quantization objects with no parameters is used.

Its parameters may be overridden by the algorithm, quantization_nsd or quantization_nsb keywords. If the “implementation” parameter is defined then it is removed (because it will get reset during a subsequent call to cf.write).

algorithm: str or None, optional

Set the “algorithm” parameter of quantization.

quantization_nsd: int or None, optional

Set the “quantization_nsd” parameter of quantization.

quantization_nsb: int or None, optional

Set the “quantization_nsb” parameter of quantization.

Returns:

None

Examples

>>> f.set_quantize_on_write(algorithm='bitgroom', quantization_nsd=6)

>>> q = cf.Quantization({'algorithm': 'bitgroom',
...                               'quantization_nsd': 6})
>>> f.set_quantize_on_write(q)

Use the quantization metadata from another construct, overriding its per-variable quantization parameter:

>>> q = g.get_quantization()
>>> f.set_quantize_on_write(q, quantization_nsd=13)