Computes the field value inside the volume of the (batched) `geometry`. The field value may be determined by integrating over the volume, sampling the central value or any other way. The batch dimensions of `geometry` are matched with this field. The `geometry` must not share any
(field: Union[Field, Geometry, FieldInitializer, Callable],
geometry: Geometry or Field or Tensor,
at: str = 'center',
boundary: Union[Extrapolation, Tensor, Number] = None,
dot_face_normal: Optional[Geometry] = None,
**kwargs)
| 73 | |
| 74 | |
| 75 | def sample(field: Union[Field, Geometry, FieldInitializer, Callable], |
| 76 | geometry: Geometry or Field or Tensor, |
| 77 | at: str = 'center', |
| 78 | boundary: Union[Extrapolation, Tensor, Number] = None, |
| 79 | dot_face_normal: Optional[Geometry] = None, |
| 80 | **kwargs) -> math.Tensor: |
| 81 | """ |
| 82 | Computes the field value inside the volume of the (batched) `geometry`. |
| 83 | |
| 84 | The field value may be determined by integrating over the volume, sampling the central value or any other way. |
| 85 | |
| 86 | The batch dimensions of `geometry` are matched with this field. |
| 87 | The `geometry` must not share any channel dimensions with this field. |
| 88 | Spatial dimensions of `geometry` can be used to sample a grid of geometries. |
| 89 | |
| 90 | See Also: |
| 91 | `Field.at()`, [Resampling overview](https://tum-pbs.github.io/PhiFlow/Fields.html#resampling-fields). |
| 92 | |
| 93 | Args: |
| 94 | field: Source `Field` to sample. |
| 95 | geometry: Single or batched `phi.geom.Geometry` or `Field` or location `Tensor`. |
| 96 | When passing a `Field`, its `elements` are used as sample points. |
| 97 | When passing a vector-valued `Tensor`, a `Point` geometry will be created. |
| 98 | at: One of 'center', 'face', 'vertex' |
| 99 | boundary: Target extrapolation. |
| 100 | dot_face_normal: If not `None` and , `field` is a vector field and `at=='face'`, the dot product between sampled field vectors and the face normals is returned instead. |
| 101 | **kwargs: Sampling arguments, e.g. to specify the numerical scheme. |
| 102 | By default, linear interpolation is used. |
| 103 | Grids also support 6th order implicit sampling at mid-points. |
| 104 | |
| 105 | Returns: |
| 106 | Sampled values as a `phi.math.Tensor` |
| 107 | """ |
| 108 | # --- Process args --- |
| 109 | assert at in ['center', 'face', 'vertex'] |
| 110 | if at == 'face': |
| 111 | assert boundary is not None, "boundaries must be given when sampling at faces" |
| 112 | geometry = _get_geometry(geometry) |
| 113 | boundary = as_boundary(boundary, geometry) if boundary is not None else None |
| 114 | if dot_face_normal is True: |
| 115 | dot_face_normal = geometry |
| 116 | if isinstance(field, Geometry): |
| 117 | from ._field_math import mask |
| 118 | field = mask(field) |
| 119 | if isinstance(field, FieldInitializer): |
| 120 | values = field._sample(geometry, at, boundary, **kwargs) |
| 121 | if dot_face_normal is not None and at == 'face' and channel(values): |
| 122 | if _are_axis_aligned(dot_face_normal.face_normals): |
| 123 | values = math.stack([values[{'vector': i, '~vector': i}] for i in range(geometry.spatial_rank)], dual(**geometry.shape['vector'].untyped_dict)) |
| 124 | else: |
| 125 | raise NotImplementedError |
| 126 | field = Field(geometry, values, boundary) |
| 127 | if callable(field): |
| 128 | values = sample_function(field, geometry, at, boundary) |
| 129 | field = Field(geometry, values, boundary) |
| 130 | # --- Resample --- |
| 131 | assert isinstance(field, Field), f"field must be a Field, Geometry or initializer but got {type(field)}" |
| 132 | if at == 'center': |
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