How To Create Bounding Box In Python

BoundingBox¶

class photutils.aperture. BoundingBox ( ixmin , ixmax , iymin , iymax ) [source] ¶

Bases: object

A rectangular bounding box in integer (not float) pixel indices.

Parameters

ixmin, ixmax, iymin, iymax int: The bounding box pixel indices. Note that the upper values ( iymax and ixmax ) are exclusive as for normal slices in Python. The lower values ( ixmin and iymin ) must not be greater than the respective upper values ( ixmax and iymax ).

Examples

                                >>>                                from                photutils.aperture                import                BoundingBox

                                >>>                                # constructing a BoundingBox like this is cryptic:                >>>                                bbox                =                BoundingBox                (                1                ,                10                ,                2                ,                20                )

                                >>>                                # it's better to use keyword arguments for readability:                >>>                                bbox                =                BoundingBox                (                ixmin                =                1                ,                ixmax                =                10                ,                iymin                =                2                ,                iymax                =                20                )                >>>                                bbox                # nice repr, useful for interactive work                BoundingBox(ixmin=1, ixmax=10, iymin=2, iymax=20)

                                >>>                                # sometimes it's useful to check if two bounding boxes are the same                >>>                                bbox                ==                BoundingBox                (                ixmin                =                1                ,                ixmax                =                10                ,                iymin                =                2                ,                iymax                =                20                )                True                >>>                                bbox                ==                BoundingBox                (                ixmin                =                7                ,                ixmax                =                10                ,                iymin                =                2                ,                iymax                =                20                )                False

                                >>>                                # "center" and "shape" can be useful when working with numpy arrays                >>>                                bbox                .                center                # numpy order: (y, x)                (10.5, 5.0)                >>>                                bbox                .                shape                # numpy order: (y, x)                (18, 9)

                                >>>                                # "extent" is useful when plotting the BoundingBox with matplotlib                >>>                                bbox                .                extent                # matplotlib order: (x, y)                (0.5, 9.5, 1.5, 19.5)

Attributes Summary

`center`	The `(y, x)` center of the bounding box.
`extent`	The extent of the mask, defined as the `(xmin, xmax, ymin, ymax)` bounding box from the bottom-left corner of the lower-left pixel to the upper-right corner of the upper-right pixel.
`shape`	The `(ny, nx)` shape of the bounding box.

Methods Summary

`as_artist` (**kwargs)	Return a `matplotlib.patches.Rectangle` that represents the bounding box.
`as_patch` (**kwargs)	Deprecated since version 0.7.
`from_float` (xmin, xmax, ymin, ymax)	Return the smallest bounding box that fully contains a given rectangle defined by float coordinate values.
`get_overlap_slices` (shape)	Get slices for the overlapping part of the bounding box and an 2D array.
`intersection` (other)	Return a `BoundingBox` representing the intersection of this `BoundingBox` with another `BoundingBox` .
`plot` ([axes, origin])	Plot the `BoundingBox` on a matplotlib `Axes` instance.
`to_aperture` ()	Return a `RectangularAperture` that represents the bounding box.
`union` (other)	Return a `BoundingBox` representing the union of this `BoundingBox` with another `BoundingBox` .

Attributes Documentation

center ¶: The (y, x) center of the bounding box.

extent ¶

The extent of the mask, defined as the (xmin, xmax, ymin, ymax) bounding box from the bottom-left corner of the lower-left pixel to the upper-right corner of the upper-right pixel.

The upper edges here are the actual pixel positions of the edges, i.e., they are not "exclusive" indices used for python indexing. This is useful for plotting the bounding box using Matplotlib.

shape ¶: The (ny, nx) shape of the bounding box.

Methods Documentation

as_artist ( ** kwargs ) [source] ¶

Return a matplotlib.patches.Rectangle that represents the bounding box.

Parameters

**kwargs dict: Any keyword arguments accepted by matplotlib.patches.Patch .

Returns

result matplotlib.patches.Rectangle: A matplotlib rectangular patch.

Examples

                                        import                    matplotlib.pyplot                    as                    plt                    from                    photutils.aperture                    import                    BoundingBox                    bbox                    =                    BoundingBox                    (                    2                    ,                    7                    ,                    3                    ,                    8                    )                    fig                    =                    plt                    .                    figure                    ()                    ax                    =                    fig                    .                    add_subplot                    (                    1                    ,                    1                    ,                    1                    )                    rng                    =                    np                    .                    random                    .                    default_rng                    (                    0                    )                    ax                    .                    imshow                    (                    rng                    .                    random                    ((                    10                    ,                    10                    )),                    interpolation                    =                    'nearest'                    ,                    cmap                    =                    'viridis'                    )                    ax                    .                    add_patch                    (                    bbox                    .                    as_artist                    (                    facecolor                    =                    'none'                    ,                    edgecolor                    =                    'white'                    ,                    lw                    =                    2.                    ))

(Source code, png, hires.png, pdf, svg)

../_images/photutils-aperture-BoundingBox-1.png

as_patch ( ** kwargs ) [source] ¶

Deprecated since version 0.7: The as_patch function is deprecated and may be removed in a future version. Use as_artist instead.

Return a matplotlib.patches.Rectangle that represents the bounding box.

Parameters

**kwargs dict: Any keyword arguments accepted by matplotlib.patches.Patch .

Returns

result matplotlib.patches.Rectangle: A matplotlib rectangular patch.

classmethod from_float ( xmin , xmax , ymin , ymax ) [source] ¶

Return the smallest bounding box that fully contains a given rectangle defined by float coordinate values.

Following the pixel index convention, an integer index corresponds to the center of a pixel and the pixel edges span from (index - 0.5) to (index + 0.5). For example, the pixel edge spans of the following pixels are:

pixel 0: from -0.5 to 0.5
pixel 1: from 0.5 to 1.5
pixel 2: from 1.5 to 2.5

In addition, because BoundingBox upper limits are exclusive (by definition), 1 is added to the upper pixel edges. See examples below.

Parameters

xmin, xmax, ymin, ymax float: Float coordinates defining a rectangle. The lower values ( xmin and ymin ) must not be greater than the respective upper values ( xmax and ymax ).

Returns

bbox BoundingBox object: The minimal BoundingBox object fully containing the input rectangle coordinates.

Examples

                                        >>>                                        from                    photutils.aperture                    import                    BoundingBox                    >>>                                        BoundingBox                    .                    from_float                    (                    xmin                    =                    1.0                    ,                    xmax                    =                    10.0                    ,                    ymin                    =                    2.0                    ,                    ymax                    =                    20.0                    )                    BoundingBox(ixmin=1, ixmax=11, iymin=2, iymax=21)

                                        >>>                                        BoundingBox                    .                    from_float                    (                    xmin                    =                    1.4                    ,                    xmax                    =                    10.4                    ,                    ymin                    =                    1.6                    ,                    ymax                    =                    10.6                    )                    BoundingBox(ixmin=1, ixmax=11, iymin=2, iymax=12)

get_overlap_slices ( shape ) [source] ¶

Get slices for the overlapping part of the bounding box and an 2D array.

Parameters

shape 2-tuple of int: The shape of the 2D array.

Returns

slices_large tuple of slices or None: A tuple of slice objects for each axis of the large array, such that large_array[slices_large] extracts the region of the large array that overlaps with the small array. None is returned if there is no overlap of the bounding box with the given image shape.
slices_small tuple of slices or None: A tuple of slice objects for each axis of an array enclosed by the bounding box such that small_array[slices_small] extracts the region that is inside the large array. None is returned if there is no overlap of the bounding box with the given image shape.

intersection ( other ) [source] ¶

Return a BoundingBox representing the intersection of this BoundingBox with another BoundingBox .

Parameters

other BoundingBox: The BoundingBox to intersect with this one.

Returns

result BoundingBox: A BoundingBox representing the intersection of the input BoundingBox with this one.

plot ( axes = None , origin = (0, 0) , ** kwargs ) [source] ¶

Plot the BoundingBox on a matplotlib Axes instance.

Parameters

axes matplotlib.axes.Axes or None , optional: The matplotlib axes on which to plot. If None , then the current Axes instance is used.
origin array_like, optional: The (x, y) position of the origin of the displayed image.
**kwargs dict: Any keyword arguments accepted by matplotlib.patches.Patch .