BaseColumnView

class lsst.afw.table.BaseColumnView

Bases: lsst.afw.table._BaseColumnViewBase

Attributes Summary

schema
table

Methods Summary

extract(*patterns, **kwds)	Extract a dictionary of {<name>: <column-array>} in which the field names match the given shell-style glob pattern(s).
get(key)	Get a column view; key may be a key object or the name of a field.
getAllBits(self)
getBits([keys])	Get the bits associated with the specified keys.
getSchema(self)
getTable(self)
get_bool_array(key)	Get the value of a flag column as a boolean array; key must be a key object or the name of a field.
set(key, value)	Set a full column to an array or scalar; key may be a key object or the name of a field.

Attributes Documentation

schema

table

Methods Documentation

extract(*patterns, **kwds)

Extract a dictionary of {<name>: <column-array>} in which the field names match the given shell-style glob pattern(s).

Any number of glob patterns may be passed (including none); the result will be the union of all the result of each glob considered separately.

Note that extract(“*”, copy=True) provides an easy way to transform a row-major ColumnView into a possibly more efficient set of contiguous NumPy arrays.

This routines unpacks Flag columns into full boolean arrays and covariances into dense (i.e. non-triangular packed) arrays with dimension (N,M,M), where N is the number of records and M is the dimension of the covariance matrix. String fields are silently ignored.

Parameters:

patterns : Array of str

List of glob patterns to use to select field names.

kwds : dict

Dictionary of additional keyword arguments. May contain:

items : list

The result of a call to self.schema.extract(); this will be used instead of doing any new matching, and allows the pattern matching to be reused to extract values from multiple records. This keyword is incompatible with any position arguments and the regex, sub, and ordered keyword arguments.

where : array index expression

Any expression that can be passed as indices to a NumPy array, including slices, boolean arrays, and index arrays, that will be used to index each column array. This is applied before arrays are copied when copy is True, so if the indexing results in an implicit copy no unnecessary second copy is performed.

copy : bool

If True, the returned arrays will be contiguous copies rather than strided views into the catalog. This ensures that the lifetime of the catalog is not tied to the lifetime of a particular catalog, and it also may improve the performance if the array is used repeatedly. Default is False.

regex : str or re pattern

A regular expression to be used in addition to any glob patterns passed as positional arguments. Note that this will be compared with re.match, not re.search.

sub : str

A replacement string (see re.MatchObject.expand) used to set the dictionary keys of any fields matched by regex.

ordered : bool

If True, a collections.OrderedDict will be returned instead of a standard dict, with the order corresponding to the definition order of the Schema. Default is False.

Returns:

d : dict

Dictionary of extracted name-column array sets.

Raises:

ValueError

Raised if a list of items is supplied with additional keywords.

get(key)

Get a column view; key may be a key object or the name of a field.

getAllBits(self: lsst.afw.table._BaseColumnViewBase) → lsst.afw.table.BitsColumn

getBits(keys=None)

Get the bits associated with the specified keys.

Parameters:

key : str

Key to retrieve. Unlike the C++ version, each key may be a field name or a key, and if keys is None then all bits are returned.

Returns:

bits : int

Integer array of the requested bitmask.

getSchema(self: lsst.afw.table._BaseColumnViewBase) → lsst.afw.table.Schema

getTable(self: lsst.afw.table.BaseColumnView) → lsst.afw.table.BaseTable

get_bool_array(key)

Get the value of a flag column as a boolean array; key must be a key object or the name of a field.

Parameters:

key : lsst.afw.table.KeyFlag

Flag column to search for.

Returns:

value : list of bool

Array of booleans corresponding to the flag.

Raises:

TypeError

Raised if the key is not a KeyFlag.

set(key, value)

Set a full column to an array or scalar; key may be a key object or the name of a field.