scipp.fold¶

scipp.fold(x, dim, sizes=None, dims=None, shape=None)¶

Fold a single dimension of a variable or data array into multiple dims.

Parameters

x (VariableLike) – Variable or DataArray to fold.
dim (str) – A single dim label that will be folded into more dims.
sizes (Optional[Dict[str, int]]) – A dict mapping new dims to new shapes.
dims (Optional[Union[List[str], Tuple[str]]]) – A list of new dims labels.
shape (Optional[Sequence[int]]) – A list of new dim shapes.

Raises

If the volume of the old shape is not equal to the volume of the new shape.

Returns

Variable or DataArray with requested dimension labels and shape.

Return type

VariableLike

Examples:

>>> v = sc.arange('x', 6)
>>> v
<scipp.Variable> (x: 6)      int64  [dimensionless]  [0, 1, ..., 4, 5]
>>> sc.fold(v, dim='x', sizes={'y': 2, 'z': 3})
<scipp.Variable> (y: 2, z: 3)      int64  [dimensionless]  [0, 1, ..., 4, 5]
>>> sc.fold(v, dim='x', sizes={'y': 2, 'z': 3}).values
array([[0, 1, 2],
       [3, 4, 5]])

>>> sc.fold(v, dim='x', dims=['y', 'z'], shape=[2, 3])
<scipp.Variable> (y: 2, z: 3)      int64  [dimensionless]  [0, 1, ..., 4, 5]

>>> a = sc.DataArray(0.1 * sc.arange('x', 6), coords={'x': sc.arange('x', 6)})
>>> sc.fold(a, dim='x', sizes={'y': 2, 'z': 3})
<scipp.DataArray>
Dimensions: Sizes[y:2, z:3, ]
Coordinates:
  x                           int64  [dimensionless]  (y, z)  [0, 1, ..., 4, 5]
Data:
                            float64  [dimensionless]  (y, z)  [0.000000, 0.100000, ..., 0.400000, 0.500000]
>>> sc.fold(a, dim='x', sizes={'y': 2, 'z': 3}).data.values
array([[0. , 0.1, 0.2],
       [0.3, 0.4, 0.5]])
>>> sc.fold(a, dim='x', sizes={'y': 2, 'z': 3}).coords['x'].values
array([[0, 1, 2],
       [3, 4, 5]])