IsophoteList#

class photutils.isophote.IsophoteList(iso_list)[source]#

Bases: object

Container class that provides the same attributes as the Isophote class, but for a list of isophotes.

The attributes of this class are arrays representing the values of the attributes for the entire list of Isophote instances. See the Isophote class for a description of the attributes.

The class extends the list functionality, thus provides basic list behavior such as slicing, appending, and support for ‘+’ and ‘+=’ operators.

Parameters:

iso_listlist of Isophote: A list of Isophote instances.

Attributes Summary

`a3`	A third-order harmonic coefficient.
`a3_err`	The error associated with `a3`.
`a4`	A fourth-order harmonic coefficient.
`a4_err`	The error associated with `a4`.
`b3`	A third-order harmonic coefficient.
`b3_err`	The error associated with `b3`.
`b4`	A fourth-order harmonic coefficient.
`b4_err`	The error associated with `b3`.
`ellip_err`	The ellipticity error.
`eps`	The ellipticity of the ellipse.
`grad`	The local radial intensity gradient.
`gradient_err`	The measurement error of the local radial intensity gradient.
`gradient_rel_err`	The relative error of local radial intensity gradient.
`int_err`	The error of the mean intensity (rms / sqrt(# data points)).
`intens`	The mean intensity value along the elliptical path.
`n_data`	The number of extracted data points.
`n_flag`	The number of discarded data points.
`n_iter`	The number of iterations used to fit the isophote.
`npix_c`	The total number of valid pixels inside a circle with the same `sma` as the ellipse.
`npix_e`	The total number of valid pixels inside the ellipse.
`pa`	The position angle (radians) of the ellipse.
`pa_err`	The position angle error (radians).
`pix_stddev`	The estimate of pixel standard deviation (rms * sqrt(average sector integration area)).
`rms`	The root-mean-square of intensity values along the elliptical path.
`sample`	The isophote `EllipseSample` information.
`sarea`	The average sector area on the isophote (pixel**2).
`sma`	The semimajor axis length (pixels).
`stop_code`	The fitting stop code.
`tflux_c`	The sum of all pixels inside a circle with the same `sma` as the ellipse.
`tflux_e`	The sum of all pixels inside the ellipse.
`valid`	The status of the fitting operation.
`x0`	The center x coordinate (pixel).
`x0_err`	The error associated with the center x coordinate.
`y0`	The center y coordinate (pixel).
`y0_err`	The error associated with the center y coordinate.

Methods Summary

`append`(value)	Append an isophote to the list.
`extend`(value)	Extend the list with the isophotes from another `IsophoteList` instance.
`get_closest`(sma)	Return the `Isophote` instance that has the closest semimajor axis length to the input semimajor axis.
`get_names`()	Get the names of the properties of an `IsophoteList` instance.
`insert`(index, value)	Insert an isophote at a given index.
`sort`()	Sort the list of isophotes by semimajor axis length.
`to_table`([columns])	Convert an `IsophoteList` instance to a `QTable` with the main isophote parameters.

Attributes Documentation

a3#

A third-order harmonic coefficient.

See the fit_upper_harmonic() function for details.

a3_err#: The error associated with a3.

a4#

A fourth-order harmonic coefficient.

See the fit_upper_harmonic() function for details.

a4_err#: The error associated with a4.

b3#

A third-order harmonic coefficient.

See the fit_upper_harmonic() function for details.

b3_err#: The error associated with b3.

b4#

A fourth-order harmonic coefficient.

See the fit_upper_harmonic() function for details.

b4_err#: The error associated with b3.

ellip_err#: The ellipticity error.

eps#: The ellipticity of the ellipse.

grad#: The local radial intensity gradient.

gradient_err#: The measurement error of the local radial intensity gradient.

gradient_rel_err#: The relative error of local radial intensity gradient.

int_err#: The error of the mean intensity (rms / sqrt(# data points)).

intens#: The mean intensity value along the elliptical path.

n_data#: The number of extracted data points.

n_flag#

The number of discarded data points.

Data points can be discarded either because they are physically outside the image frame boundaries, because they were rejected by sigma-clipping, or they are masked.

n_iter#: The number of iterations used to fit the isophote.

npix_c#: The total number of valid pixels inside a circle with the same sma as the ellipse.

npix_e#: The total number of valid pixels inside the ellipse.

pa#: The position angle (radians) of the ellipse.

pa_err#: The position angle error (radians).

pix_stddev#: The estimate of pixel standard deviation (rms * sqrt(average sector integration area)).

rms#: The root-mean-square of intensity values along the elliptical path.

sample#: The isophote EllipseSample information.

sarea#: The average sector area on the isophote (pixel**2).

sma#: The semimajor axis length (pixels).

stop_code#: The fitting stop code.

tflux_c#: The sum of all pixels inside a circle with the same sma as the ellipse.

tflux_e#: The sum of all pixels inside the ellipse.

valid#: The status of the fitting operation.

x0#: The center x coordinate (pixel).

x0_err#: The error associated with the center x coordinate.

y0#: The center y coordinate (pixel).

y0_err#: The error associated with the center y coordinate.

Methods Documentation

append(value)[source]#

Append an isophote to the list.

Parameters:

valueIsophote: The isophote to be appended.

extend(value)[source]#

Extend the list with the isophotes from another IsophoteList instance.

Parameters:

valueIsophoteList: The isophotes to be appended.

get_closest(sma)[source]#

Return the Isophote instance that has the closest semimajor axis length to the input semimajor axis.

Parameters:

smafloat: The semimajor axis length.

Returns:

isophoteIsophote instance: The isophote with the closest semimajor axis value.

get_names()[source]#

Get the names of the properties of an IsophoteList instance.

Returns:

list_nameslist: A list of the names of the properties.

insert(index, value)[source]#

Insert an isophote at a given index.

Parameters:

indexint: The index where to insert the isophote.
valueIsophote: The isophote to be inserted.

sort()[source]#: Sort the list of isophotes by semimajor axis length.

to_table(columns='main')[source]#

Convert an IsophoteList instance to a QTable with the main isophote parameters.

Parameters:

columnslist of str: A list of properties to export from the isophote list. If columns is ‘all’ or ‘main’, it will pick all or few of the main properties.

Returns:

resultQTable: An astropy QTable with the main isophote parameters.