Geom#

class gammapy.maps.Geom[source]#

Bases: ABC

Map geometry base class.

See also: WcsGeom and HpxGeom.

Attributes Summary

`as_energy_true`	If the geom contains an axis named 'energy' rename it to 'energy_true'.
`center_coord`
`center_pix`
`center_skydir`
`data_shape`	Shape of the Numpy data array matching this geometry.
`has_energy_axis`	Whether geom has an energy axis (either 'energy' or 'energy_true').
`is_allsky`
`is_flat`	Whether the geom non-spatial axes have length 1, equivalent to an image.
`is_image`	Whether the geom is an image without extra dimensions.

Methods Summary

`contains`(coords)	Check if a given map coordinate is contained in the geometry.
`contains_pix`(pix)	Check if a given pixel coordinate is contained in the geometry.
`coord_to_idx`(coords[, clip])	Convert map coordinates to pixel indices.
`coord_to_pix`(coords)	Convert map coordinates to pixel coordinates.
`copy`(**kwargs)	Copy and overwrite given attributes.
`crop`(crop_width)	Crop the geometry at the edges.
`data_nbytes`([dtype])	Estimate memory usage in megabytes of the Numpy data array matching this geometry depending on the given type.
`downsample`(factor, axis_name)	Downsample the spatial dimension of the geometry by a given factor.
`drop`(axis_name)	Drop an axis from the geom.
`energy_mask`([energy_min, energy_max, ...])	Create a mask for a given energy range.
`from_hdulist`(hdulist[, hdu, hdu_bands])	Load a geometry object from a FITS HDUList.
`get_coord`([idx, flat])	Get the coordinate array for this geometry.
`get_idx`([idx, local, flat])	Get tuple of pixel indices for this geometry.
`pad`(pad_width, axis_name)	Pad the geometry at the edges.
`pix_to_coord`(pix)	Convert pixel coordinates to map coordinates.
`pix_to_idx`(pix[, clip])	Convert pixel coordinates to pixel indices.
`rename_axes`(names, new_names)	Rename axes contained in the geometry.
`replace_axis`(axis)	Replace axis with a new one.
`resample_axis`(axis)	Resample geom to a new axis binning.
`slice_by_idx`(slices)	Create a new geometry by slicing the non-spatial axes.
`solid_angle`()	Solid angle as a `Quantity` object (in `sr`).
`squash`(axis_name)	Squash geom axis.
`to_bands_hdu`([hdu_bands, format])
`to_cube`(axes)	Append non-spatial axes to create a higher-dimensional geometry.
`to_image`()	Create a 2D image geometry (drop non-spatial dimensions).
`upsample`(factor[, axis_name])	Upsample the spatial dimension of the geometry by a given factor.

Attributes Documentation

as_energy_true#: If the geom contains an axis named ‘energy’ rename it to ‘energy_true’.

center_coord#

center_pix#

center_skydir#

data_shape#: Shape of the Numpy data array matching this geometry.

has_energy_axis#: Whether geom has an energy axis (either ‘energy’ or ‘energy_true’).

is_allsky#

is_flat#: Whether the geom non-spatial axes have length 1, equivalent to an image.

is_image#: Whether the geom is an image without extra dimensions.

Methods Documentation

abstract contains(coords)[source]#

Check if a given map coordinate is contained in the geometry.

Parameters:

coordstuple or MapCoord: Tuple of map coordinates.

Returns:

containmentndarray: Bool array.

contains_pix(pix)[source]#

Check if a given pixel coordinate is contained in the geometry.

Parameters:

pixtuple: Tuple of pixel coordinates.

Returns:

containmentndarray: Bool array.

coord_to_idx(coords, clip=False)[source]#

Convert map coordinates to pixel indices.

Parameters:

coordstuple or MapCoord: Coordinate values in each dimension of the map. This can either be a tuple of numpy arrays or a MapCoord object. If passed as a tuple then the ordering should be (longitude, latitude, c_0, …, c_N) where c_i is the coordinate vector for axis i.
clipbool: Choose whether to clip indices to the valid range of the geometry. If False then indices for coordinates outside the geometry range will be set -1. Default is False.

Returns:

pixtuple: Tuple of pixel indices in image and band dimensions. Elements set to -1 correspond to coordinates outside the map.

abstract coord_to_pix(coords)[source]#

Convert map coordinates to pixel coordinates.

Parameters:

coordstuple: Coordinate values in each dimension of the map. This can either be a tuple of numpy arrays or a MapCoord object. If passed as a tuple then the ordering should be (longitude, latitude, c_0, …, c_N) where c_i is the coordinate vector for axis i.

Returns:

pixtuple: Tuple of pixel coordinates in image and band dimensions.

copy(**kwargs)[source]#

Copy and overwrite given attributes.

Parameters:

**kwargsdict: Keyword arguments to overwrite in the map geometry constructor.

Returns:

copyGeom: Copied map geometry.

abstract crop(crop_width)[source]#

Crop the geometry at the edges.

Parameters:

crop_width{sequence, array_like, int}: Number of values cropped from the edges of each axis.

Returns:

geomGeom: Cropped geometry.

data_nbytes(dtype='float32')[source]#

Estimate memory usage in megabytes of the Numpy data array matching this geometry depending on the given type.

Parameters:

dtypestr, optional: The desired data-type for the array. Default is “float32”.

Returns:

memoryQuantity: Estimated memory usage in megabytes (MB).

abstract downsample(factor, axis_name)[source]#

Downsample the spatial dimension of the geometry by a given factor.

Parameters:

factorint: Downsampling factor.
axis_namestr: Axis to downsample.

Returns:

geomGeom: Downsampled geometry.

drop(axis_name)[source]#

Drop an axis from the geom.

Parameters:

axis_namestr: Name of the axis to remove.

Returns:

geomGeom: New geom with the axis removed.

energy_mask(energy_min=None, energy_max=None, round_to_edge=False)[source]#

Create a mask for a given energy range.

The energy bin must be fully contained to be included in the mask.

Parameters:

energy_min, energy_maxQuantity: Energy range.

Returns:

maskMap: Map containing the energy mask. The geometry of the map is the same as the geometry of the instance which called this method.

classmethod from_hdulist(hdulist, hdu=None, hdu_bands=None)[source]#

Load a geometry object from a FITS HDUList.

Parameters:

hdulistHDUList: HDU list containing HDUs for map data and bands.
hdustr or int, optional: Name or index of the HDU with the map data. Default is None.
hdu_bandsstr, optional: Name or index of the HDU with the BANDS table. If not defined this will be inferred from the FITS header of the map HDU. Default is None.

Returns:

geomGeom: Geometry object.

abstract get_coord(idx=None, flat=False)[source]#

Get the coordinate array for this geometry.

Returns a coordinate array with the same shape as the data array. Pixels outside the geometry are set to NaN. Coordinates for a single image plane can be accessed by setting idx to the index tuple of a plane.

Parameters:

idxtuple, optional: A tuple of indices with one index for each non-spatial dimension. If defined only coordinates for the image plane with this index will be returned. If none then coordinates for all pixels will be returned. Default is None.
flatbool, optional: Return a flattened array containing only coordinates for pixels contained in the geometry. Default is False.

Returns:

coordstuple: Tuple of coordinate vectors with one vector for each dimension.

abstract get_idx(idx=None, local=False, flat=False)[source]#

Get tuple of pixel indices for this geometry.

Returns all pixels in the geometry by default. Pixel indices for a single image plane can be accessed by setting idx to the index tuple of a plane.

Parameters:

idxtuple, optional: A tuple of indices with one index for each non-spatial dimension. If defined only pixels for the image plane with this index will be returned. If none then all pixels will be returned. Default is None.
localbool, optional: Flag to return local or global pixel indices. Local indices run from 0 to the number of pixels in a given image plane. Default is False.
flatbool, optional: Return a flattened array containing only indices for pixels contained in the geometry. Default is False.

Returns:

idxtuple: Tuple of pixel index vectors with one vector for each dimension.

pad(pad_width, axis_name)[source]#

Pad the geometry at the edges.

Parameters:

pad_width{sequence, array_like, int}: Number of values padded to the edges of each axis.
axis_namestr: Name of the axis to pad.

Returns:

geomGeom: Padded geometry.

abstract pix_to_coord(pix)[source]#

Convert pixel coordinates to map coordinates.

Parameters:

pixtuple: Tuple of pixel coordinates.

Returns:

coordstuple: Tuple of map coordinates.

abstract pix_to_idx(pix, clip=False)[source]#

Convert pixel coordinates to pixel indices.

Returns -1 for pixel coordinates that lie outside the map.

Parameters:

pixtuple: Tuple of pixel coordinates.
clipbool: Choose whether to clip indices to the valid range of the geometry. If False then indices for coordinates outside the geometry range will be set -1. Default is False.

Returns:

idxtuple: Tuple of pixel indices.

rename_axes(names, new_names)[source]#

Rename axes contained in the geometry.

Parameters:

nameslist or str: Names of the axes.
new_nameslist or str: New names of the axes. The list must be of same length than names.

Returns:

geomGeom: Renamed geometry.

replace_axis(axis)[source]#

Replace axis with a new one.

Parameters:

axisMapAxis: New map axis.

Returns:

mapGeom: Geom with replaced axis.

resample_axis(axis)[source]#

Resample geom to a new axis binning.

This method groups the existing bins into a new binning.

Parameters:

axisMapAxis: New map axis.

Returns:

mapGeom: Geom with resampled axis.

slice_by_idx(slices)[source]#

Create a new geometry by slicing the non-spatial axes.

Parameters:

slicesdict: Dictionary of axes names and integers or slice object pairs. Contains one element for each non-spatial dimension. For integer indexing the corresponding axes is dropped from the map. Axes not specified in the dict are kept unchanged.

Returns:

geomGeom: Sliced geometry.

Examples

>>> from gammapy.maps import MapAxis, WcsGeom
>>> import astropy.units as u
>>> energy_axis = MapAxis.from_energy_bounds(1*u.TeV, 3*u.TeV, 6)
>>> geom = WcsGeom.create(skydir=(83.63, 22.01), axes=[energy_axis], width=5, binsz=0.02)
>>> slices = {"energy": slice(0, 2)}
>>> sliced_geom = geom.slice_by_idx(slices)

abstract solid_angle()[source]#: Solid angle as a Quantity object (in sr).

squash(axis_name)[source]#

Squash geom axis.

Parameters:

axis_namestr: Axis to squash.

Returns:

geomGeom: Geom with squashed axis.

to_bands_hdu(hdu_bands=None, format='gadf')[source]#

abstract to_cube(axes)[source]#

Append non-spatial axes to create a higher-dimensional geometry.

This will result in a new geometry with N+M dimensions where N is the number of current dimensions and M is the number of axes in the list.

Parameters:

axeslist: Axes that will be appended to this geometry.

Returns:

geomGeom: Map geometry.

abstract to_image()[source]#

Create a 2D image geometry (drop non-spatial dimensions).

Returns:

geomGeom: Image geometry.

abstract upsample(factor, axis_name=None)[source]#

Upsample the spatial dimension of the geometry by a given factor.

Parameters:

factorint: Upsampling factor.
axis_namestr: Axis to upsample.

Returns:

geomGeom: Upsampled geometry.