Bases: object
Container class to store the results of single isophote fit.
The extracted data sample at the given isophote (sampled intensities along the elliptical path on the image) is also kept as an attribute of this class. The container concept helps in segregating information directly related to the sample, from information that more closely relates to the fitting process, such as status codes, errors for isophote parameters, and the like.
EllipseSample instance
The sample information.
The number of iterations used to fit the isophote.
The status of the fitting operation.
The fitting stop code:
0: Normal.
1: Fewer than the pre-specified fraction of the extracted data points are valid.
2: Exceeded maximum number of iterations.
3: Singular matrix in harmonic fit, results may not be valid. This also signals an insufficient number of data points to fit.
4: Small or wrong gradient, or ellipse diverged. Subsequent ellipses at larger or smaller semimajor axis may have the same constant geometric parameters. It’s also used when the user turns off the fitting algorithm via the
maxritfitting parameter (see theEllipseclass).5: Ellipse diverged; not even the minimum number of iterations could be executed. Subsequent ellipses at larger or smaller semimajor axis may have the same constant geometric parameters.
-1: Internal use.
The root-mean-square of intensity values along the elliptical path.
The error of the mean (rms / sqrt(# data points)).
The ellipticity error.
The position angle error (radians).
The error associated with the center x coordinate.
The error associated with the center y coordinate.
The estimate of pixel standard deviation (rms * sqrt(average sector integration area)).
The local radial intensity gradient.
The measurement error of the local radial intensity gradient.
The relative error of local radial intensity gradient.
The sum of all pixels inside the ellipse.
The total number of valid pixels inside the ellipse.
The sum of all pixels inside a circle with the same sma as the ellipse.
The total number of valid pixels inside a circle with the same sma as the ellipse.
The average sector area on the isophote (pixel**2).
The number of extracted data points.
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.
The higher order harmonics that measure the deviations from a perfect ellipse. These values are actually the raw harmonic amplitudes divided by the local radial gradient and the semimajor axis length, so they can directly be compared with each other. The b4 parameter is positive for galaxies with disky (kite-like) isophotes and negative for galaxies with boxy isophotes.
The errors associated with the a3, b3, a4, and b4 attributes.
Attributes Summary
Methods Summary
Attributes Documentation
The ellipticity of the ellipse.
The position angle (radians) of the ellipse.
The semimajor axis length (pixels).
The center x coordinate (pixel).
The center y coordinate (pixel).
Methods Documentation
Fix the geometry of a problematic isophote to be identical to the input isophote.
This method should be called when the fitting goes berserk and delivers an isophote with bad geometry, such as ellipticity > 1 or another meaningless situation. This is not a problem in itself when fitting any given isophote, but will create an error when the affected isophote is used as starting guess for the next fit.
Isophote instance
The isophote from which to take the geometry information.
Return the (x, y) coordinates where the image was sampled in order to get the intensities associated with this isophote.
ndarray
The x and y coordinates as 1D arrays.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4