astrodendro.analysis

class astrodendro.analysis.PPStatistic(stat, metadata=None)

Compute properties of structures in a position-position (PP) cube.

Parameters:

structure : Structure instance

The structure to compute the statistics for

metadata : dict

Key-value 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 position-position (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 position-position (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 counter-clockwise 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 semi-major and semi-minor axes used are the HWHM (half-width at half-maximum) 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 meta-data).
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 meta-data).
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 position-position-velocity (PPV) cube.

Parameters:

structure : Structure instance

The structure to compute the statistics for

metadata : dict

Key-value 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 position-position (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 position-position (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 counter-clockwise 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 semi-major and semi-minor axes used are the HWHM (half-width at half-maximum) 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	Intensity-weighted 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 position-position (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 instance

The resulting catalog

astrodendro.analysis.ppv_catalog(structures, metadata, fields=None, verbose=True)

Iterate over a collection of position-position-velocity (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 instance

The resulting catalog