pystencils.field.fields

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pystencils.field.fields#

pystencils.field.fields(description=None, index_dimensions=0, layout=None, field_type=FieldType.GENERIC, **kwargs)#

Creates pystencils fields from a string description.

The description must be a string of the form "name(index-shape) [name(index-shape) ...]: <data-type>[<dimension-or-shape>]", where:

  • name is the name of the respective field

  • (index-shape) is a tuple of integers describing the shape of the tensor on each field node (can be omitted for scalar fields)

  • <data-type> is the numerical data type of the field’s entries; this can be any type parseable by create_type, as well as dyn for DynamicType.NUMERIC_TYPE and dynidx for DynamicType.INDEX_TYPE.

  • <dimension-or-shape> can be a dimensionality (e.g. 1D, 2D, 3D) or a tuple of integers defining the spatial shape of the field.

Examples

Create a 3D scalar field of default numeric type:
>>> f = fields("f(1): [2D]")
>>> str(f.dtype)
'DynamicType.NUMERIC_TYPE'
Create a 2D scalar and vector field of 64-bit float type:
>>> s, v = fields("s, v(2): double[2D]")
>>> assert s.spatial_dimensions == 2 and s.index_dimensions == 0
>>> assert (v.spatial_dimensions, v.index_dimensions, v.index_shape) == (2, 1, (2,))
Create an integer field of shape (10, 20):
>>> f = fields("f : int32[10, 20]")
>>> f.has_fixed_shape, f.shape
(True, (10, 20))
Numpy arrays can be used as template for shape and data type of field:
>>> arr_s, arr_v = np.zeros([20, 20]), np.zeros([20, 20, 2])
>>> s, v = fields("s, v(2)", s=arr_s, v=arr_v)
>>> assert s.index_dimensions == 0 and s.dtype.numpy_dtype == arr_s.dtype
>>> assert v.index_shape == (2,)
Format string can be left out, field names are taken from keyword arguments.
>>> fields(f1=arr_s, f2=arr_s)
[f1: float64[20,20], f2: float64[20,20]]
The keyword names index_dimension and layout have special meaning, don’t use them for field names
>>> f = fields(f=arr_v, index_dimensions=1)
>>> assert f.index_dimensions == 1
>>> f = fields("pdfs(19) : float32[3D]", layout='fzyx')
>>> f.layout
(2, 1, 0)
Return type:

Field | list[Field]

Returns:

Sequence of fields created from the description

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