MaskedColumn¶
-
class
astropy.table.
MaskedColumn
[source] [edit on github]¶ Bases:
astropy.table.Column
,astropy.table._column_mixins._MaskedColumnGetitemShim
,numpy.ma.MaskedArray
Define a masked data column for use in a Table object.
Parameters: - data : list, ndarray or None
Column data values
- name : str
Column name and key for reference within Table
- mask : list, ndarray or None
Boolean mask for which True indicates missing or invalid data
- fill_value : float, int, str or None
Value used when filling masked column elements
- dtype : numpy.dtype compatible value
Data type for column
- shape : tuple or ()
Dimensions of a single row element in the column data
- length : int or 0
Number of row elements in column data
- description : str or None
Full description of column
- unit : str or None
Physical unit
- format : str or None or function or callable
Format string for outputting column values. This can be an “old-style” (
format % value
) or “new-style” (str.format
) format specification string or a function or any callable object that accepts a single value and returns a string.- meta : dict-like or None
Meta-data associated with the column
Examples
A MaskedColumn is similar to a Column except that it includes
mask
andfill_value
attributes. It can be created in two different ways:Provide a
data
value but notshape
orlength
(which are inferred from the data).Examples:
col = MaskedColumn(data=[1, 2], name='name') col = MaskedColumn(data=[1, 2], name='name', mask=[True, False]) col = MaskedColumn(data=[1, 2], name='name', dtype=float, fill_value=99)
The
mask
argument will be cast as a boolean array and specifies which elements are considered to be missing or invalid.The
dtype
argument can be any value which is an acceptable fixed-size data-type initializer for the numpy.dtype() method. See https://docs.scipy.org/doc/numpy/reference/arrays.dtypes.html. Examples include:- Python non-string type (float, int, bool)
- Numpy non-string type (e.g. np.float32, np.int64, np.bool_)
- Numpy.dtype array-protocol type strings (e.g. ‘i4’, ‘f8’, ‘S15’)
If no
dtype
value is provide then the type is inferred usingnp.array(data)
. Whendata
is provided then theshape
andlength
arguments are ignored.Provide
length
and optionallyshape
, but notdata
Examples:
col = MaskedColumn(name='name', length=5) col = MaskedColumn(name='name', dtype=int, length=10, shape=(3,4))
The default
dtype
isnp.float64
. Theshape
argument is the array shape of a single cell in the column.
Attributes Summary
data
Return the current data, as a view of the original underlying data. fill_value
Filling value. info
Container for meta information like name, description, format. name
The name of this column. Methods Summary
convert_unit_to
(new_unit[, equivalencies])Converts the values of the column in-place from the current unit to the given unit. copy
([order, data, copy_data])Return a copy of the current instance. filled
([fill_value])Return a copy of self, with masked values filled with a given value. insert
(obj, values[, mask, axis])Insert values along the given axis before the given indices and return a new MaskedColumn
object.more
([max_lines, show_name, show_unit])Interactively browse column with a paging interface. pformat
([max_lines, show_name, show_unit, …])Return a list of formatted string representation of column values. pprint
([max_lines, show_name, show_unit, …])Print a formatted string representation of column values. Attributes Documentation
-
data
¶ Return the current data, as a view of the original underlying data.
-
fill_value
¶ Filling value.
-
info
¶ Container for meta information like name, description, format.
This is required when the object is used as a mixin column within a table, but can be used as a general way to store meta information. In this case it just adds the
mask_val
attribute.
-
name
¶ The name of this column.
Methods Documentation
-
convert_unit_to
(new_unit, equivalencies=[]) [edit on github]¶ Converts the values of the column in-place from the current unit to the given unit.
To change the unit associated with this column without actually changing the data values, simply set the
unit
property.Parameters: - new_unit : str or
astropy.units.UnitBase
instance The unit to convert to.
- equivalencies : list of equivalence pairs, optional
A list of equivalence pairs to try if the unit are not directly convertible. See Equivalencies.
Raises: - astropy.units.UnitsError
If units are inconsistent
- new_unit : str or
-
copy
(order='C', data=None, copy_data=True) [edit on github]¶ Return a copy of the current instance.
If
data
is supplied then a view (reference) ofdata
is used, andcopy_data
is ignored.Parameters: - order : {‘C’, ‘F’, ‘A’, ‘K’}, optional
Controls the memory layout of the copy. ‘C’ means C-order, ‘F’ means F-order, ‘A’ means ‘F’ if
a
is Fortran contiguous, ‘C’ otherwise. ‘K’ means match the layout ofa
as closely as possible. (Note that this function and :func:numpy.copy are very similar, but have different default values for their order= arguments.) Default is ‘C’.- data : array, optional
If supplied then use a view of
data
instead of the instance data. This allows copying the instance attributes and meta.- copy_data : bool, optional
Make a copy of the internal numpy array instead of using a reference. Default is True.
Returns: - col : Column or MaskedColumn
Copy of the current column (same type as original)
-
filled
(fill_value=None)[source] [edit on github]¶ Return a copy of self, with masked values filled with a given value.
Parameters: Returns: - filled_column : Column
A copy of
self
with masked entries replaced byfill_value
(be it the function argument or the attribute ofself
).
-
insert
(obj, values, mask=None, axis=0)[source] [edit on github]¶ Insert values along the given axis before the given indices and return a new
MaskedColumn
object.Parameters: - obj : int, slice or sequence of ints
Object that defines the index or indices before which
values
is inserted.- values : array_like
Value(s) to insert. If the type of
values
is different from that of quantity,values
is converted to the matching type.values
should be shaped so that it can be broadcast appropriately- mask : boolean array_like
Mask value(s) to insert. If not supplied then False is used.
- axis : int, optional
Axis along which to insert
values
. Ifaxis
is None then the column array is flattened before insertion. Default is 0, which will insert a row.
Returns: - out :
MaskedColumn
A copy of column with
values
andmask
inserted. Note that the insertion does not occur in-place: a new masked column is returned.
-
more
(max_lines=None, show_name=True, show_unit=False) [edit on github]¶ Interactively browse column with a paging interface.
Supported keys:
f, <space> : forward one page b : back one page r : refresh same page n : next row p : previous row < : go to beginning > : go to end q : quit browsing h : print this help
Parameters: - max_lines : int
Maximum number of lines in table output.
- show_name : bool
Include a header row for column names. Default is True.
- show_unit : bool
Include a header row for unit. Default is False.
-
pformat
(max_lines=None, show_name=True, show_unit=False, show_dtype=False, html=False) [edit on github]¶ Return a list of formatted string representation of column values.
If no value of
max_lines
is supplied then the height of the screen terminal is used to setmax_lines
. If the terminal height cannot be determined then the default will be determined using theastropy.conf.max_lines
configuration item. If a negative value ofmax_lines
is supplied then there is no line limit applied.Parameters: - max_lines : int
Maximum lines of output (header + data rows)
- show_name : bool
Include column name. Default is True.
- show_unit : bool
Include a header row for unit. Default is False.
- show_dtype : bool
Include column dtype. Default is False.
- html : bool
Format the output as an HTML table. Default is False.
Returns: - lines : list
List of lines with header and formatted column values
-
pprint
(max_lines=None, show_name=True, show_unit=False, show_dtype=False) [edit on github]¶ Print a formatted string representation of column values.
If no value of
max_lines
is supplied then the height of the screen terminal is used to setmax_lines
. If the terminal height cannot be determined then the default will be determined using theastropy.conf.max_lines
configuration item. If a negative value ofmax_lines
is supplied then there is no line limit applied.Parameters: - max_lines : int
Maximum number of values in output
- show_name : bool
Include column name. Default is True.
- show_unit : bool
Include a header row for unit. Default is False.
- show_dtype : bool
Include column dtype. Default is True.