astrodendro.analysis¶

class
astrodendro.analysis.
PPStatistic
(stat, metadata=None)¶ Compute properties of structures in a positionposition (PP) cube.
Parameters: structure :
Structure
instanceThe structure to compute the statistics for
metadata : dict
Keyvalue pairs of metadata
Available statistics
flux 
The integrated flux of the structure, in Jy (note that this does not include any kind of background subtraction, and is just a plain sum of the values in the structure, converted to Jy). 
major_sigma 
Major axis of the projection onto the positionposition (PP) plane, computed from the intensity weighted second moment in direction of greatest elongation in the PP plane. 
minor_sigma 
Minor axis of the projection onto the positionposition (PP) plane, computed from the intensity weighted second moment perpendicular to the major axis in the PP plane. 
position_angle 
The position angle of sky_maj, sky_min in degrees counterclockwise from the +x axis. 
radius 
Geometric mean of major_sigma and minor_sigma . 
area_exact 
The exact area of the structure on the sky. 
area_ellipse 
The area of the ellipse defined by the second moments, where the semimajor and semiminor axes used are the HWHM (halfwidth at halfmaximum) derived from the moments. 
x_cen 
The mean position of the structure in the x direction (in pixel coordinates, or in world coordinates if the WCS transformation is available in the metadata). 
y_cen 
The mean position of the structure in the y direction (in pixel coordinates, or in world coordinates if the WCS transformation is available in the metadata). 
to_mpl_ellipse (**kwargs) 
Returns a Matplotlib ellipse representing the first and second moments of the structure. 
Methods (detail)

PPStatistic.
to_mpl_ellipse
(**kwargs)¶ Returns a Matplotlib ellipse representing the first and second moments of the structure.
Any keyword arguments are passed to
Ellipse

class
astrodendro.analysis.
PPVStatistic
(stat, metadata=None)¶ Compute properties of structures in a positionpositionvelocity (PPV) cube.
Parameters: structure :
Structure
instanceThe structure to compute the statistics for
metadata : dict
Keyvalue pairs of metadata
Available statistics
flux 
The integrated flux of the structure, in Jy (note that this does not include any kind of background subtraction, and is just a plain sum of the values in the structure, converted to Jy). 
major_sigma 
Major axis of the projection onto the positionposition (PP) plane, computed from the intensity weighted second moment in direction of greatest elongation in the PP plane. 
minor_sigma 
Minor axis of the projection onto the positionposition (PP) plane, computed from the intensity weighted second moment perpendicular to the major axis in the PP plane. 
position_angle 
The position angle of sky_maj, sky_min in degrees counterclockwise from the +x axis (note that this is the +x axis in pixel coordinates, which is the x axis for conventional astronomy images). 
radius 
Geometric mean of major_sigma and minor_sigma . 
area_exact 
The exact area of the structure on the sky. 
area_ellipse 
The area of the ellipse defined by the second moments, where the semimajor and semiminor axes used are the HWHM (halfwidth at halfmaximum) derived from the moments. 
x_cen 
The mean position of the structure in the x direction. 
y_cen 
The mean position of the structure in the y direction. 
v_cen 
The mean velocity of the structure (where the velocity axis can be specified by the vaxis metadata parameter, which defaults to 0 following the Numpy convention  the third axis in the FITS convention). 
v_rms 
Intensityweighted second moment of velocity (where the velocity axis can be specified by the vaxis metadata parameter, which defaults to 0 following the Numpy convention  the third axis in the FITS convention). 
to_mpl_ellipse (**kwargs) 
Returns a Matplotlib ellipse representing the first and second moments of the structure. 
Methods (detail)

PPStatistic.
to_mpl_ellipse
(**kwargs) Returns a Matplotlib ellipse representing the first and second moments of the structure.
Any keyword arguments are passed to
Ellipse

astrodendro.analysis.
pp_catalog
(structures, metadata, fields=None, verbose=True)¶ Iterate over a collection of positionposition (PP) structures, extracting several quantities from each, and building a catalog.
Parameters: structures : iterable of Structures
The structures to catalog (e.g., a dendrogram)
metadata : dict
The metadata used to compute the catalog
fields : list of strings, optional
The quantities to extract. If not provided, defaults to all PPV statistics
verbose : bool, optional
If True (the default), will generate warnings about missing metadata
Returns: table : a
Table
instanceThe resulting catalog

astrodendro.analysis.
ppv_catalog
(structures, metadata, fields=None, verbose=True)¶ Iterate over a collection of positionpositionvelocity (PPV) structures, extracting several quantities from each, and building a catalog.
Parameters: structures : iterable of Structures
The structures to catalog (e.g., a dendrogram)
metadata : dict
The metadata used to compute the catalog
fields : list of strings, optional
The quantities to extract. If not provided, defaults to all PPV statistics
verbose : bool, optional
If True (the default), will generate warnings about missing metadata
Returns: table : a
Table
instanceThe resulting catalog