# core.reference.slices¶

## Module: `core.reference.slices`¶

A set of methods to get coordinate maps which represent slices in space.

## Functions¶

nipy.core.reference.slices.bounding_box(coordmap, shape)

Determine a valid bounding box from a CoordinateMap and a shape.

Parameters:
coordmapCoordinateMap or AffineTransform

Containing mapping between voxel coordinates implied by shape and physical coordinates.

shapesequence of int

shape implying array

Returns:
limits(N,) tuple of (2,) tuples of float

minimum and maximum coordinate values in output space (range) of coordmap. N is given by coordmap.ndim[1].

Examples

Make a 3D voxel to mni coordmap

```>>> from nipy.core.api import vox2mni
>>> affine = np.array([[1, 0, 0, 2],
...                    [0, 3, 0, 4],
...                    [0, 0, 5, 6],
...                    [0, 0, 0, 1]], dtype=np.float64)
>>> A = vox2mni(affine)
>>> bounding_box(A, (30,40,20))
((2.0, 31.0), (4.0, 121.0), (6.0, 101.0))
```
nipy.core.reference.slices.xslice(x, y_spec, z_spec, world)

Return an LPS slice through a 3d box with x fixed.

Parameters:
xfloat

The value at which x is fixed.

y_specsequence

A sequence with 2 values of form ((float, float), int). The (float, float) components are the min and max y values; the int is the number of points.

z_specsequence

As for y_spec but for z

worldstr or CoordinateSystem CoordSysMaker or XYZSpace

World 3D space to which resulting coordmap refers

Returns:
affine_transformAffineTransform

An affine transform that describes an plane in LPS coordinates with x fixed.

Examples

```>>> y_spec = ([-114,114], 115) # voxels of size 2 in y, starting at -114, ending at 114
>>> z_spec = ([-70,100], 86) # voxels of size 2 in z, starting at -70, ending at 100
>>> x30 = xslice(30, y_spec, z_spec, 'scanner')
>>> x30([0,0])
array([  30., -114.,  -70.])
>>> x30([114,85])
array([  30.,  114.,  100.])
>>> x30
AffineTransform(
function_domain=CoordinateSystem(coord_names=('i_y', 'i_z'), name='slice', coord_dtype=float64),
function_range=CoordinateSystem(coord_names=('scanner-x=L->R', 'scanner-y=P->A', 'scanner-z=I->S'), name='scanner', coord_dtype=float64),
affine=array([[   0.,    0.,   30.],
[   2.,    0., -114.],
[   0.,    2.,  -70.],
[   0.,    0.,    1.]])
)
>>> bounding_box(x30, (y_spec[1], z_spec[1]))
((30.0, 30.0), (-114.0, 114.0), (-70.0, 100.0))
```
nipy.core.reference.slices.yslice(y, x_spec, z_spec, world)

Return a slice through a 3d box with y fixed.

Parameters:
yfloat

The value at which y is fixed.

x_specsequence

A sequence with 2 values of form ((float, float), int). The (float, float) components are the min and max x values; the int is the number of points.

z_specsequence

As for x_spec but for z

worldstr or CoordinateSystem CoordSysMaker or XYZSpace

World 3D space to which resulting coordmap refers

Returns:
affine_transformAffineTransform

An affine transform that describes an plane in LPS coordinates with y fixed.

Examples

```>>> x_spec = ([-92,92], 93) # voxels of size 2 in x, starting at -92, ending at 92
>>> z_spec = ([-70,100], 86) # voxels of size 2 in z, starting at -70, ending at 100
>>> y70 = yslice(70, x_spec, z_spec, 'mni')
>>> y70
AffineTransform(
function_domain=CoordinateSystem(coord_names=('i_x', 'i_z'), name='slice', coord_dtype=float64),
function_range=CoordinateSystem(coord_names=('mni-x=L->R', 'mni-y=P->A', 'mni-z=I->S'), name='mni', coord_dtype=float64),
affine=array([[  2.,   0., -92.],
[  0.,   0.,  70.],
[  0.,   2., -70.],
[  0.,   0.,   1.]])
)
>>> y70([0,0])
array([-92.,  70., -70.])
>>> y70([92,85])
array([  92.,   70.,  100.])
>>> bounding_box(y70, (x_spec[1], z_spec[1]))
((-92.0, 92.0), (70.0, 70.0), (-70.0, 100.0))
```
nipy.core.reference.slices.zslice(z, x_spec, y_spec, world)

Return a slice through a 3d box with z fixed.

Parameters:
zfloat

The value at which z is fixed.

x_specsequence

A sequence with 2 values of form ((float, float), int). The (float, float) components are the min and max x values; the int is the number of points.

y_specsequence

As for x_spec but for y

worldstr or CoordinateSystem CoordSysMaker or XYZSpace

World 3D space to which resulting coordmap refers

Returns:
affine_transformAffineTransform

An affine transform that describes a plane in LPS coordinates with z fixed.

Examples

```>>> x_spec = ([-92,92], 93) # voxels of size 2 in x, starting at -92, ending at 92
>>> y_spec = ([-114,114], 115) # voxels of size 2 in y, starting at -114, ending at 114
>>> z40 = zslice(40, x_spec, y_spec, 'unknown')
>>> z40
AffineTransform(
function_domain=CoordinateSystem(coord_names=('i_x', 'i_y'), name='slice', coord_dtype=float64),
function_range=CoordinateSystem(coord_names=('unknown-x=L->R', 'unknown-y=P->A', 'unknown-z=I->S'), name='unknown', coord_dtype=float64),
affine=array([[   2.,    0.,  -92.],
[   0.,    2., -114.],
[   0.,    0.,   40.],
[   0.,    0.,    1.]])
)
>>> z40([0,0])
array([ -92., -114.,   40.])
>>> z40([92,114])
array([  92.,  114.,   40.])
>>> bounding_box(z40, (x_spec[1], y_spec[1]))
((-92.0, 92.0), (-114.0, 114.0), (40.0, 40.0))
```