utils - Utilities#

gammapy.utils.coordinates Package#

Astronomical coordinate calculation utility functions.

Functions#

`cartesian`(r, theta)	Convert polar coordinates to cartesian coordinates.
`fov_to_sky`(lon, lat, lon_pnt, lat_pnt)	Transform field-of-view coordinates to sky coordinates.
`galactic`(x, y, z[, obs_pos])	Compute galactic coordinates lon, lat and distance.
`motion_since_birth`(v, age, theta, phi)	Compute motion of a object with given velocity, direction and age.
`polar`(x, y)	Convert cartesian coordinates to polar coordinates.
`sky_to_fov`(lon, lat, lon_pnt, lat_pnt)	Transform sky coordinates to field-of-view coordinates.
`velocity_glon_glat`(x, y, z, vx, vy, vz)	Compute projected angular velocity in galactic coordinates.

Variables#

D_SUN_TO_GALACTIC_CENTER

A Quantity represents a number with some associated unit.

gammapy.utils.integrate Module#

Functions#

trapz_loglog(y, x[, axis])

Integrate using the composite trapezoidal rule in log-log space.

gammapy.utils.interpolation Module#

Interpolation utilities

Functions#

`interpolate_profile`(x, y[, interp_scale])	Helper function to interpolate one-dimensional profiles.
`interpolation_scale`([scale])	Interpolation scaling.

Classes#

ScaledRegularGridInterpolator(points, values)

Thin wrapper around scipy.interpolate.RegularGridInterpolator.

gammapy.utils.fits Module#

Functions#

earth_location_from_dict(meta)

Create EarthLocation from FITS header dict.

Classes#

`LazyFitsData`([cache])	A lazy FITS data descriptor.
`HDULocation`(hdu_class[, base_dir, file_dir, ...])	HDU localisation, loading and Gammapy object mapper.

gammapy.utils.random Package#

Random probability distribution helpers.

Functions#

`draw`(low, high, size, dist[, random_state])	Allows drawing of random numbers from any distribution.
`get_random_state`(init)	Get a `numpy.random.RandomState` instance.
`normalize`(func, x_min, x_max)	Normalize a 1D function over a given range.
`pdf`(func)	One-dimensional PDF of a given radial surface density.
`sample_powerlaw`(x_min, x_max, gamma[, size, ...])	Sample random values from a power law distribution.
`sample_sphere`(size[, lon_range, lat_range, ...])	Sample random points on the sphere.
`sample_sphere_distance`([distance_min, ...])	Sample random distances if the 3-dim space density is constant.
`sample_times`(size, rate[, dead_time, ...])	Make random times assuming a Poisson process.

Classes#

InverseCDFSampler(pdf[, axis, random_state])

Inverse CDF sampler.

gammapy.utils.regions Module#

Regions helper functions.

Throughout Gammapy, we use regions to represent and work with regions.

https://astropy-regions.readthedocs.io

We might add in other conveniences and features here, e.g. sky coord contains without a WCS (see “sky and pixel regions” in PIG 10), or some HEALPix integration.

TODO: before Gammapy v1.0, discuss what to do about gammapy.utils.regions. Options: keep as-is, hide from the docs, or to remove it completely (if the functionality is available in astropy-regions directly.

Functions#

`compound_region_to_regions`(region)	Create list of regions from compound regions.
`make_concentric_annulus_sky_regions`(center, ...)	Make a list of concentric annulus regions.
`make_orthogonal_rectangle_sky_regions`(...[, ...])	Utility returning an array of regions to make orthogonal projections
`regions_to_compound_region`(regions)	Create compound region from list of regions, by creating the union.

gammapy.utils.scripts Module#

Utils to create scripts and command-line tools

Functions#

`get_images_paths`([folder])	Generator yields a Path for each image used in notebook.
`make_path`(path)	Expand environment variables on `Path` construction.
`read_yaml`(filename[, logger])	Read YAML file.
`recursive_merge_dicts`(a, b)	Recursively merge two dictionaries.
`write_yaml`(dictionary, filename[, logger, ...])	Write YAML file.

gammapy.utils.table Module#

Table helper utilities.

Functions#

`hstack_columns`(table, table_other)	Stack the column data horizontally
`table_from_row_data`(rows, **kwargs)	Helper function to create table objects from row data.
`table_row_to_dict`(row[, make_quantity])	Make one source data dict.
`table_standardise_units_copy`(table)	Standardise units for all columns in a table in a copy.
`table_standardise_units_inplace`(table)	Standardise units for all columns in a table in place.

gammapy.utils.testing Module#

Utilities for testing

Functions#

`assert_quantity_allclose`(actual, desired[, ...])	Assert all-close for `astropy.units.Quantity` objects.
`assert_skycoord_allclose`(actual, desired)	Assert all-close for `astropy.coordinates.SkyCoord` objects.
`assert_time_allclose`(actual, desired[, atol])	Assert all-close for `astropy.time.Time` objects.
`mpl_plot_check`()	Matplotlib plotting test context manager.
`requires_data`([name])	Decorator to declare required data for tests.
`requires_dependency`(name)	Decorator to declare required dependencies for tests.

Classes#

Checker()

Base class for checker classes in Gammapy.

gammapy.utils.time Module#

Time related utility functions.

Functions#

`absolute_time`(time_delta, meta)	Convert a MET into human readable date and time.
`time_ref_from_dict`(meta[, format, scale])	Calculate the time reference from metadata.
`time_ref_to_dict`(time[, scale])	TODO: document and test.
`time_relative_to_ref`(time, meta)	Convert a time using an existing reference.

gammapy.utils.units Module#

Units and Quantity related helper functions

Functions#

`standardise_unit`(unit)	Standardise unit.
`unit_from_fits_image_hdu`(header)	Read unit from a FITS image HDU.