pysersic.priors

Attributes

`base_sky_types`
`base_sky_params`
`base_profile_types`
`base_profile_params`

Classes

`BaseSkyPrior`
`NoSkyPrior`
`FlatSkyPrior`
`TiltedPlaneSkyPrior`
`BasePrior`
`PySersicSourcePrior`	Class used for priors for single source fitting in PySersic
`PySersicMultiPrior`	Class used for priors for multi source fitting in PySersic
`SourceProperties`	A Class used to estimate initial guesses for source properties.

Functions

`render_tilted_plane_sky`(X, Y, back, x_sl, y_sl)
`update_prior_suffix`(→ BasePrior)	Change the suffix of a pysersic prior
`estimate_sky`(→ Tuple[float, float, int])	Estimate the sky background using the edge of the cutout
`autoprior`(→ PySersicSourcePrior)	Simple wrapper function to generate a prior using the built-in defaults. This can be used as a starting place but may not work for all sources

Module Contents

pysersic.priors.base_sky_types = ['none', 'flat', 'tilted-plane']

pysersic.priors.base_sky_params

pysersic.priors.render_tilted_plane_sky(X, Y, back, x_sl, y_sl)

pysersic.priors.base_profile_types = ['sersic', 'doublesersic', 'sersic_exp', 'sersic_pointsource', 'pointsource', 'exp', 'dev', 'spergel']

pysersic.priors.base_profile_params

class pysersic.priors.BaseSkyPrior(sky_guess: float, sky_guess_err: float, suffix: str = '')

Bases: equinox.Module

type: eqx.AbstractClassVar()

repr_dict: dict

suffix: str

dist_dict: dict

reparam_dict: dict

abstract sample(X: jax.numpy.array, Y: jax.numpy.array)

update_prior(name: str, mu: float, sigma: float)

Update prior for a given parameter, assumed to be Gaussian with mu and sigma

Parameters:

name (str) – Name of parameter
mu (float) – Location for prior
sigma (float) – width of prior

__repr__()

class pysersic.priors.NoSkyPrior(sky_guess: float, sky_guess_err: float, suffix: str = '')

Bases: BaseSkyPrior

type: str = 'None'

sample(X, Y)

class pysersic.priors.FlatSkyPrior(sky_guess: float, sky_guess_err: float, suffix: str = '')

Bases: BaseSkyPrior

type: str = 'flat'

sample(X, Y)

class pysersic.priors.TiltedPlaneSkyPrior(sky_guess: float, sky_guess_err: float, suffix: str = '')

Bases: BaseSkyPrior

type: str = 'TiltedPlane'

sample(X, Y)

class pysersic.priors.BasePrior(sky_type='none', sky_guess=None, sky_guess_err=None, suffix='')

Bases: equinox.Module

sky_type: str

repr_dict: dict

suffix: str

dist_dict: dict

reparam_dict: dict

sky_prior: equinox.Module: Base class for priors with sky sampling included

property param_names

sample_sky(X: jax.numpy.array, Y: jax.numpy.array) → float

Sample sky parameters and return sky model

Parameters:

X (jax.numpy.array) – 2D mesh grid of pixel x pixel indices
Y (jax.numpy.array) – 2D mesh grid of pixel y pixel indices

Returns:

sampled and rendered sky model

Return type:

float

_set_dist(var_name: str, dist: BasePrior._set_dist.dist) → None

Set prior for a given variable

Parameters:

var_name (str) – variable name
dist (dist.Distribution) – Numpyro distribution object specifying prior

_get_dist(var_name: str) → numpyro.distributions.Distribution

Get prior for a given variable

Parameters:: var_name (str) – variable name
Returns:: Numpyro distribution clas describing prior
Return type:: dist.Distribution

set_gaussian_prior(var_name: str, loc: float, scale: float) → PySersicSourcePrior

Set a Gaussian prior for a variable

Parameters:

var_name (str) – variable name
loc (float) – mean
scale (float) – standard deviation

Returns:

returns self to allow chaining

Return type:

PySersicSourcePrior

set_uniform_prior(var_name: str, low: float, high: float) → PySersicSourcePrior

Set a uniform prior for a variable

Parameters:

var_name (str) – variable name
low (float) – lower bound
high (float) – upper bound

Returns:

returns self to allow chaining

Return type:

PySersicSourcePrior

set_truncated_gaussian_prior(var_name: str, loc: float, scale: float, low: float | None = None, high: float | None = None) → PySersicSourcePrior

Set a truncated Gaussian prior for a given variable

Parameters:

var_name (str) – variable name
loc (float) – mean
scale (float) – standard deviation
low (Optional[float], optional) – lower bound, by default None
high (Optional[float], optional) – upper bound, by default None

Returns:

Returns self to allow chaining

Return type:

PySersicSourcePrior

set_custom_prior(var_name: str, prior_dist: numpyro.distributions.Distribution, reparam: numpyro.infer.reparam.Reparam | None = None) → PySersicSourcePrior

Set a custom distribution as the prior for a given variable

Parameters:

var_name (str) – variable name
prior_dist (dist.Distribution) – Numpyro Distribution object describing prior
reparam (Optional[infer.reparam.Reparam], optional) – Optional reparamaterization to use for variable, by default None

Returns:

Returns self to allow chaining

Return type:

PySersicSourcePrior

__call__() → jax.numpy.array

Sample variables from prior

Returns:: sampled variables
Return type:: jax.numpy.array

class pysersic.priors.PySersicSourcePrior(profile_type: str, sky_type: str | None = 'none', sky_guess: float | None = None, sky_guess_err: float | None = None, suffix: str | None = '')

Bases: BasePrior

Class used for priors for single source fitting in PySersic

profile_type: str

__repr__() → str

check_vars(verbose=False) → bool

Function to check if all variable for the specified profile type are set with no extras

Parameters:: verbose (bool, optional) – Wheter to print out missing and extra variables, by default False
Returns:: True if all variable for given type are present with no extra, False otherwise
Return type:: bool

Bases: BasePrior

Class used for priors for multi source fitting in PySersic

catalog: dict

N_sources: int

suffix = ''

__repr__() → str

pysersic.priors.update_prior_suffix(prior: BasePrior, new_suffix: str) → BasePrior

Change the suffix of a pysersic prior

Parameters:

prior (BasePrior) – Either a Source or Multi Prior,
new_suffix (str) – new suffix for variables

Returns:

Prior with updated suffix

Return type:

BasePrior

class pysersic.priors.SourceProperties(image: numpy.array | jax.numpy.array, mask: numpy.array | jax.numpy.array = None)

A Class used to estimate initial guesses for source properties. If no guesses are provided, then the class will estimate them using the photutls package and the data_properties() function.

measure_properties(**kwargs) → SourceProperties

Measure default properties of the source

Returns:: returns self
Return type:: SourceProperties

set_sky_guess(sky_guess: float | None = None, sky_guess_err: float | None = None, n_pix_sample: int = 5, **kwargs) → SourceProperties

Measure or set guess for initial sky background level. If no estimate is provided, the median of the n_pix_sample number of pixels around each edge is used

Parameters:

sky_guess (Optional[float], optional) – Initial guess for level of background, by default None
sky_guess_err (Optional[float], optional) – Uncertainity on inital guess, by default None
n_pix_sample (int, optional) – Number of pixels around each edge to use to estimate sky level if neccesary, by default 5

Returns:

returns self

Return type:

SourceProperties

set_flux_guess(flux_guess: float | None = None, flux_guess_err: float | None = None, **kwargs) → SourceProperties

Measure or set guess for initial flux. If no estimate is provided, the flux of the source in estimated as the total flux within the sgmentatated region for the source

Parameters:

flux_guess (Optional[float], optional) – Initial guess for flux, by default None
flux_guess_err (Optional[float], optional) – Uncertainty on initial guess, by default None

Returns:

returns self

Return type:

SourceProperties

set_r_eff_guess(r_eff_guess: float | None = None, r_eff_guess_err: float | None = None, **kwargs) → SourceProperties

Measure or set guess for effective radius. If no estimate is provided, the r_eff of the source in estimated using photutils

Parameters:

r_eff_guess (Optional[float], optional) – Initial guess for effective radius, by default None
r_eff_guess_err (Optional[float], optional) – Uncertainty on initial guess, by default None

Returns:

returns self

Return type:

SourceProperties

set_theta_guess(theta_guess: float | None = None, **kwargs) → SourceProperties

Measure or set guess for initial position angle. If no estimate is provided, the position angle of the source in estimated using the data_properties() function from photutils

Parameters:: theta_guess (Optional[float], optional) – Estimate of the position angle in radians, by default None
Returns:: returns self
Return type:: SourceProperties

set_position_guess(position_guess: Iterable[float, float] | None = None, **kwargs) → SourceProperties

Measure or set guess for initial position. If no estimate is provided, the position of the source in estimated using the data_properties() function from photutils

Parameters:: position_guess (Optional[Iterable[float,float]], optional) – A 2 element list, tuple or array which contain the x,y pixel values of the inital guess for the centroid, by default None
Returns:: returns self
Return type:: SourceProperties

generate_prior(profile_type: str, sky_type: str | None = 'none', suffix: str | None = '') → PySersicSourcePrior

Function to generate default priors based on a given image and profile type

Parameters:

profile_type (str) – Type of profile
sky_type (str, default 'none') – Type of sky model to use, must be one of: ‘none’, ‘flat’, ‘tilted-plane’
suffix (str, default '') – Add suffix onto all source related variables, generally only used to number sources in MultiPrior

Returns:

Pysersic prior object to be used to initialize FitSingle

Return type:

PySersicSourcePrior

visualize(figsize: Tuple[float, float] = (6.0, 6.0), cmap: str = 'gray', scale: float = 1.0) → None

Display a figure summarizing the current guess for the source properties

Parameters:

figsize (Tuple[float,float], optional) – figure, by default (6.,6.)
cmap (str, optional) – color map, by default ‘gray’
scale (float, optional) – number of +/- std’s at which to clip image, by default 1

pysersic.priors.estimate_sky(image: numpy.array, mask: numpy.array | None = None, n_pix_sample: int = 5) → Tuple[float, float, int]

Estimate the sky background using the edge of the cutout

Parameters:

im (np.array) – image, either an array or masked array
mask (Optional[np.array], optional) – mask to apply, if im is not a masked array already, by default None
n_pix_sample (int, optional) – number of pixels around the edge to use, by default 5

Returns:

a tuple containing the median, standard deviation and number of pixels used

Return type:

Tuple[float,float,int]

pysersic.priors.autoprior(image: numpy.array, profile_type: str, mask: numpy.array = None, sky_type: str = 'none') → PySersicSourcePrior

Simple wrapper function to generate a prior using the built-in defaults. This can be used as a starting place but may not work for all sources

Parameters:

image (np.array) – science image
profile_type (str) – Type of profile to be fit
mask (np.array, optional) – pixel by pixel mask, by default None
sky_type (str) – Type of sky to fit, default ‘none’

Returns:

Prior object that can be used in initializing FitSingle

Return type:

PySersicSourcePrior