# Moment_AT — Generates various moment maps of a cube.¶

This module defines the Moment_AT class.

class admit.at.Moment_AT.Moment_AT(**keyval)[source]

AT for generating moments from an input cube BDP.

The produced Moment_BDP(s) hold moment images and line information for the produced moments.

Keywords
moments: list of ints

The moments to be computed. An individual BDP is created for each moment. See CASA’s immoments documentation for a description of the moments that can be computed. Default: [0]. Moments are:

• -1 - mean value of the spectrum
• 0 - integrated value of the spectrum
• 1 - intensity weighted coordinate;traditionally used to get ‘velocity fields’
• 2 - intensity weighted dispersion of the coordinate; traditionally used to get “velocity dispersion”
• 3 - median of I
• 4 - median coordinate
• 5 - standard deviation about the mean of the spectrum
• 6 - root mean square of the spectrum
• 7 - absolute mean deviation of the spectrum
• 8 - maximum value of the spectrum
• 9 - coordinate of the maximum value of the spectrum
• 10 - minimum value of the spectrum
numsigma: list of floats
The lower cutoff level for each moment in terms of sigma, an entry for each moment can be given, or a single value can be given which will be applied to all moments. Default: [2.0].
sigma: float
The noise level to be used for calculating the cutoff values. Negative values indicate that the AT should compute the value. Inherited from the global RMS found in the CubeStats_BDP, if provided. Default: -1.0.
chans: string
The 0-based channels to operate on, in normal CASA style. Examples are “2~10” for channels 2 through 10. Default: “” (all channels).
mom0clip: float
The clip level in the mom0 map below which other moment maps will be masked, but not to the mom0 map. This is in sigma units of that moment-0 map. Default: 0.0 (not applied).
zoom: int
Image zoom ratio applied to the moment map plots. This does not affect the base (CASA) image itself. Default: 1.

Input BDPs

SpwCube_BDP or LineCube_BDP: count: 1
Spectral cube to take the moment(s) of, as from an Ingest_AT, ContinuumSub_AT or LineCube_AT.
CubeStats_BDP: count: 1 (optional)
Use for determining the noise level for cutoffs. Normally from a CubeStats_AT.

Output BDPs

Moment_BDP: count: varies
Calculated moments, one for each moment requested.
Parameters: keyval : dictionary of keyword:value pairs, optional

Attributes

 _version (string) Version information.

Methods

 addinput(item[, slot]) Add a BDP input to an AT. addinputbdp(item[, slot, insert]) Add a BDP to the _bdp_in list. addoutput(item[, slot]) Add a BDP output product to an AT. addoutputbdp(item[, slot, insert]) Add a BDP to the _bdp_out list. baseDir([path]) Get/set project base directory. bestMatch(at1, at2) Determines the better match of two tasks to the current one. checkfiles() Check if the files from all the BDP_out’s in an AT exist. checktype(item) Check the type of an object to see if it is a BDP. clearinput() Clear the input BDP list. clearoutput([delete]) Clear the output BDP list. copy() Creates an independent duplicate of the task. delete() Method to delete the AT and underlying BDPs. delinput(slot) Delete a specific BDP in the _bdp_in list. deloutput(slot) Delete a specific BDP in the _bdp_out list. dir([filename]) Absolute directory reference of the ADMIT project. dryrun() Method to do a dry run of the AT, generally just checks input values for errors. enabled([state]) Returns current task enabled setting, with optional reset. execute([args]) Executes the task. freeAlias(aliases[, alias]) Deletes alias reservation, if present. get(attrib) Method to get the given attributes value getProject() Retrieves project ID associated with the task. getVersion() Return the version string. getdtd(fl) Method to write out the dtd data. geteffectivelevel() Method to get the effective logging level of the logging subsystem getkey(key) Retrieval value for a key. getloggername() Method to get the name of the logger for this AT instance getlogginglevel() Method to get the current logging level of the AT haskey(key) Query if a key exists for an AT. html(inheader) Method to represent the current AT in HTML format. id([strip]) Returns task ID number. isAutoAlias([withEmpty, compat]) Whether the task alias appears to be auto-generated. isequal(at) Method to determine if two ATs are the same. isstale() Returns whether the AT is out of date. len2() Returns the length of _bdp_in and _bdp_out in a tuple. link() Increments the task link count. markChanged() Mark an AT that it’s state was changed, so it would need to be rerun. markUpToDate() Resets _stale to indicate that the AT does not need to be run. merge(at[, aliases]) Merges attributes from another task. mkdir(dirname) Make a directory in the ADMIT hierarchy. mkext(filename, ext[, alias]) Return a new filename with a new extension with optional ADMIT alias. newId(tid) Assigns the task a new ID number. reset(a) Performs an in-place shallow copy. run() The run method, calculates the moments and creates the BDP(s) running([state]) Returns current task execution flag, with optional reset. save() Save (write) any BDPs connected to this AT. set(item, val) Method to set protected attributes, rather than direct access setAlias(aliases[, alias, auto]) Sets and registers the task alias, guaranteed unique among registered aliases. setProject(pid) Adds a project ID to task ID. set_bdp_in([bdpin]) Validate the _valid_bdp_in list and digest it into the appropriate attributes. set_bdp_out([bout]) Validate the _valid_bdp_out list and digest it into the appropriate attributes. seteffectivelevel(level) Method to set the effective logging level of the logging subsystem setkey([name, value, isinit]) Set keyword value. setloggername(name) Method to set the name of the logger for this AT instance setlogginglevel(level) Method to set the logging level show() Return the AT type. statusicons() return some html icons representing the enabled/stale status of this task summary() Returns the summary dictionary from the AT, for merging into the ADMIT Summary object. unlink() Decrements the task link count. userdata() Returns the user dictionary from the AT, for merging into the ADMIT userdata object. validateinput([describe]) Method to validate the _bdp_in’s against a dictionary of expected types. validatekeys() Method to error check all input keys. write(node) Method to write the AT to disk.
run()[source]

The run method, calculates the moments and creates the BDP(s)

Parameters: None None
summary()[source]

Returns the summary dictionary from the AT, for merging into the ADMIT Summary object.

admit.at.Moment_AT.nppb(image)[source]

work out the flux correction, number of points per beam