ObservationTable¶

class gammapy.data.ObservationTable(data=None, masked=False, names=None, dtype=None, meta=None, copy=True, rows=None, copy_indices=True, **kwargs)[source]¶

Bases: astropy.table.Table

Observation table.

Data format specification: Observation index table

Attributes Summary

`ColumnClass`
`colnames`
`dtype`
`groups`
`has_masked_columns`	True if table has any `MaskedColumn` columns.
`has_masked_values`	True if column in the table has values which are masked.
`has_mixin_columns`	True if table has any mixin columns (defined as columns that are not Column subclasses).
`iloc`	Return a TableILoc object that can be used for retrieving indexed rows in the order they appear in the index.
`indices`	Return the indices associated with columns of the table as a TableIndices object.
`info`
`loc`	Return a TableLoc object that can be used for retrieving rows by index in a given data range.
`loc_indices`	Return a TableLocIndices object that can be used for retrieving the row indices corresponding to given table index key value or values.
`mask`
`masked`
`meta`
`pointing_galactic`	Pointing positions as Galactic (`SkyCoord`).
`pointing_radec`	Pointing positions as ICRS (`SkyCoord`).
`time_ref`	Time reference (`Time`).
`time_start`	Observation start time (`Time`).
`time_stop`	Observation stop time (`Time`).
`write`

Methods Summary

`add_column`(col[, index, name, …])	Add a new column to the table using `col` as input.
`add_columns`(cols[, indexes, names, copy, …])	Add a list of new columns the table using `cols` data objects.
`add_index`(colnames[, engine, unique])	Insert a new index among one or more columns.
`add_row`([vals, mask])	Add a new row to the end of the table.
`argsort`([keys, kind, reverse])	Return the indices which would sort the table according to one or more key columns.
`as_array`([keep_byteorder, names])	Return a new copy of the table in the form of a structured np.ndarray or np.ma.MaskedArray object (as appropriate).
`convert_bytestring_to_unicode`()	Convert bytestring columns (dtype.kind=’S’) to unicode (dtype.kind=’U’) using UTF-8 encoding.
`convert_unicode_to_bytestring`()	Convert unicode columns (dtype.kind=’U’) to bytestring (dtype.kind=’S’) using UTF-8 encoding.
`copy`([copy_data])	Return a copy of the table.
`field`(item)	Return column[item] for recarray compatibility.
`filled`([fill_value])	Return copy of self, with masked values filled.
`from_pandas`(dataframe[, index])	Create a `Table` from a `pandas.DataFrame` instance
`get_obs_idx`(obs_id)	Get row index for given `obs_id`.
`group_by`(keys)	Group this table by the specified `keys`
`index_column`(name)	Return the positional index of column `name`.
`index_mode`(mode)	Return a context manager for an indexing mode.
`insert_row`(index[, vals, mask])	Add a new row before the given `index` position in the table.
`itercols`()	Iterate over the columns of this table.
`iterrows`(*names)	Iterate over rows of table returning a tuple of values for each row.
`keep_columns`(names)	Keep only the columns specified (remove the others).
`keys`()
`more`([max_lines, max_width, show_name, …])	Interactively browse table with a paging interface.
`pformat`([max_lines, max_width, show_name, …])	Return a list of lines for the formatted string representation of
`pformat_all`([max_lines, max_width, …])	Return a list of lines for the formatted string representation of
`pprint`([max_lines, max_width, show_name, …])	Print a formatted string representation of the table.
`pprint_all`([max_lines, max_width, …])	Print a formatted string representation of the entire table.
`read`(filename, **kwargs)	Read an observation table from file.
`remove_column`(name)	Remove a column from the table.
`remove_columns`(names)	Remove several columns from the table.
`remove_indices`(colname)	Remove all indices involving the given column.
`remove_row`(index)	Remove a row from the table.
`remove_rows`(row_specifier)	Remove rows from the table.
`rename_column`(name, new_name)	Rename a column.
`rename_columns`(names, new_names)	Rename multiple columns.
`replace_column`(name, col[, copy])	Replace column `name` with the new `col` object.
`reverse`()	Reverse the row order of table rows.
`select_obs_id`(obs_id)	Get `ObservationTable` containing only `obs_id`.
`select_observations`([selection])	Select subset of observations.
`select_range`(selection_variable, value_range)	Make an observation table, applying some selection.
`select_time_range`(time_range[, …])	Make an observation table, applying a time selection.
`show_in_browser`([max_lines, jsviewer, …])	Render the table in HTML and show it in a web browser.
`show_in_notebook`([tableid, css, …])	Render the table in HTML and show it in the IPython notebook.
`sort`([keys, reverse])	Sort the table according to one or more keys.
`summary`()	Summary info string (str).
`to_pandas`([index])	Return a `pandas.DataFrame` instance
`values_equal`(other)	Element-wise comparison of table with another table, list, or scalar.

Attributes Documentation

ColumnClass¶

colnames¶

dtype¶

groups¶

has_masked_columns¶

True if table has any MaskedColumn columns.

This does not check for mixin columns that may have masked values, use the has_masked_values property in that case.

has_masked_values¶

True if column in the table has values which are masked.

This may be relatively slow for large tables as it requires checking the mask values of each column.

has_mixin_columns¶: True if table has any mixin columns (defined as columns that are not Column subclasses).

iloc¶: Return a TableILoc object that can be used for retrieving indexed rows in the order they appear in the index.

indices¶: Return the indices associated with columns of the table as a TableIndices object.

info¶

loc¶: Return a TableLoc object that can be used for retrieving rows by index in a given data range. Note that both loc and iloc work only with single-column indices.

loc_indices¶: Return a TableLocIndices object that can be used for retrieving the row indices corresponding to given table index key value or values.

mask¶

masked¶

meta¶

pointing_galactic¶: Pointing positions as Galactic (SkyCoord).

pointing_radec¶: Pointing positions as ICRS (SkyCoord).

time_ref¶: Time reference (Time).

time_start¶: Observation start time (Time).

time_stop¶: Observation stop time (Time).

write = <astropy.table.connect.TableWrite object>¶

Methods Documentation

add_column(col, index=None, name=None, rename_duplicate=False, copy=True, default_name=None)¶

Add a new column to the table using col as input. If index is supplied then insert column before index position in the list of columns, otherwise append column to the end of the list.

The col input can be any data object which is acceptable as a Table column object or can be converted. This includes mixin columns and scalar or length=1 objects which get broadcast to match the table length.

To add several columns at once use add_columns() or simply call add_column() for each one. There is very little performance difference in the two approaches.

Parameters

colobject: Data object for the new column
indexint or None: Insert column before this position or at end (default).
namestr: Column name
rename_duplicatebool: Uniquify column name if it already exist. Default is False.
copybool: Make a copy of the new column. Default is True.
default_namestr or None: Name to use if both name and col.info.name are not available. Defaults to col{number_of_columns}.

Examples

Create a table with two columns ‘a’ and ‘b’, then create a third column ‘c’ and append it to the end of the table:

>>> t = Table([[1, 2], [0.1, 0.2]], names=('a', 'b'))
>>> col_c = Column(name='c', data=['x', 'y'])
>>> t.add_column(col_c)
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y

Add column ‘d’ at position 1. Note that the column is inserted before the given index:

>>> t.add_column(['a', 'b'], name='d', index=1)
>>> print(t)
 a   d   b   c
--- --- --- ---
  1   a 0.1   x
  2   b 0.2   y

Add second column named ‘b’ with rename_duplicate:

>>> t = Table([[1, 2], [0.1, 0.2]], names=('a', 'b'))
>>> t.add_column(1.1, name='b', rename_duplicate=True)
>>> print(t)
 a   b  b_1
--- --- ---
  1 0.1 1.1
  2 0.2 1.1

Add an unnamed column or mixin object in the table using a default name or by specifying an explicit name with name. Name can also be overridden:

>>> t = Table([[1, 2], [0.1, 0.2]], names=('a', 'b'))
>>> t.add_column(['a', 'b'])
>>> t.add_column(col_c, name='d')
>>> print(t)
 a   b  col2  d
--- --- ---- ---
  1 0.1    a   x
  2 0.2    b   y

add_columns(cols, indexes=None, names=None, copy=True, rename_duplicate=False)¶

Add a list of new columns the table using cols data objects. If a corresponding list of indexes is supplied then insert column before each index position in the original list of columns, otherwise append columns to the end of the list.

The cols input can include any data objects which are acceptable as Table column objects or can be converted. This includes mixin columns and scalar or length=1 objects which get broadcast to match the table length.

From a performance perspective there is little difference between calling this method once or looping over the new columns and calling add_column() for each column.

Parameters

colslist of objects: List of data objects for the new columns
indexeslist of ints or None: Insert column before this position or at end (default).
nameslist of str: Column names
copybool: Make a copy of the new columns. Default is True.
rename_duplicatebool: Uniquify new column names if they duplicate the existing ones. Default is False.

Examples

Create a table with two columns ‘a’ and ‘b’, then create columns ‘c’ and ‘d’ and append them to the end of the table:

>>> t = Table([[1, 2], [0.1, 0.2]], names=('a', 'b'))
>>> col_c = Column(name='c', data=['x', 'y'])
>>> col_d = Column(name='d', data=['u', 'v'])
>>> t.add_columns([col_c, col_d])
>>> print(t)
 a   b   c   d
--- --- --- ---
  1 0.1   x   u
  2 0.2   y   v

Add column ‘c’ at position 0 and column ‘d’ at position 1. Note that the columns are inserted before the given position:

>>> t = Table([[1, 2], [0.1, 0.2]], names=('a', 'b'))
>>> t.add_columns([['x', 'y'], ['u', 'v']], names=['c', 'd'],
...               indexes=[0, 1])
>>> print(t)
 c   a   d   b
--- --- --- ---
  x   1   u 0.1
  y   2   v 0.2

Add second column ‘b’ and column ‘c’ with rename_duplicate:

>>> t = Table([[1, 2], [0.1, 0.2]], names=('a', 'b'))
>>> t.add_columns([[1.1, 1.2], ['x', 'y']], names=('b', 'c'),
...               rename_duplicate=True)
>>> print(t)
 a   b  b_1  c
--- --- --- ---
  1 0.1 1.1  x
  2 0.2 1.2  y

Add unnamed columns or mixin objects in the table using default names or by specifying explicit names with names. Names can also be overridden:

>>> t = Table()
>>> col_b = Column(name='b', data=['u', 'v'])
>>> t.add_columns([[1, 2], col_b])
>>> t.add_columns([[3, 4], col_b], names=['c', 'd'])
>>> print(t)
col0  b   c   d
---- --- --- ---
   1   u   3   u
   2   v   4   v

add_index(colnames, engine=None, unique=False)¶

Insert a new index among one or more columns. If there are no indices, make this index the primary table index.

Parameters

colnamesstr or list: List of column names (or a single column name) to index
enginetype or None: Indexing engine class to use, from among SortedArray, BST, FastBST, FastRBT, and SCEngine. If the supplied argument is None (by default), use SortedArray.
uniquebool: Whether the values of the index must be unique. Default is False.

add_row(vals=None, mask=None)¶

Add a new row to the end of the table.

The vals argument can be:

sequence (e.g. tuple or list): Column values in the same order as table columns.
mapping (e.g. dict): Keys corresponding to column names. Missing values will be filled with np.zeros for the column dtype.
None: All values filled with np.zeros for the column dtype.

This method requires that the Table object “owns” the underlying array data. In particular one cannot add a row to a Table that was initialized with copy=False from an existing array.

The mask attribute should give (if desired) the mask for the values. The type of the mask should match that of the values, i.e. if vals is an iterable, then mask should also be an iterable with the same length, and if vals is a mapping, then mask should be a dictionary.

Parameters

valstuple, list, dict or None: Use the specified values in the new row
masktuple, list, dict or None: Use the specified mask values in the new row

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1,2],[4,5],[7,8]], names=('a','b','c'))
>>> print(t)
 a   b   c
--- --- ---
  1   4   7
  2   5   8

Adding a new row with entries ‘3’ in ‘a’, ‘6’ in ‘b’ and ‘9’ in ‘c’:

>>> t.add_row([3,6,9])
>>> print(t)
  a   b   c
  --- --- ---
  1   4   7
  2   5   8
  3   6   9

argsort(keys=None, kind=None, reverse=False)¶

Return the indices which would sort the table according to one or more key columns. This simply calls the numpy.argsort function on the table with the order parameter set to keys.

Parameters

keysstr or list of str: The column name(s) to order the table by
kind{‘quicksort’, ‘mergesort’, ‘heapsort’}, optional: Sorting algorithm.
reversebool: Sort in reverse order (default=False)

Returns

index_arrayndarray, int: Array of indices that sorts the table by the specified key column(s).

as_array(keep_byteorder=False, names=None)¶

Return a new copy of the table in the form of a structured np.ndarray or np.ma.MaskedArray object (as appropriate).

Parameters

keep_byteorderbool, optional: By default the returned array has all columns in native byte order. However, if this option is True this preserves the byte order of all columns (if any are non-native).
nameslist, optional:: List of column names to include for returned structured array. Default is to include all table columns.

Returns

table_arraynp.ndarray (unmasked) or np.ma.MaskedArray (masked): Copy of table as a numpy structured array

convert_bytestring_to_unicode()¶

Convert bytestring columns (dtype.kind=’S’) to unicode (dtype.kind=’U’) using UTF-8 encoding.

Internally this changes string columns to represent each character in the string with a 4-byte UCS-4 equivalent, so it is inefficient for memory but allows scripts to manipulate string arrays with natural syntax.

convert_unicode_to_bytestring()¶

Convert unicode columns (dtype.kind=’U’) to bytestring (dtype.kind=’S’) using UTF-8 encoding.

When exporting a unicode string array to a file, it may be desirable to encode unicode columns as bytestrings.

copy(copy_data=True)¶

Return a copy of the table.

Parameters

copy_databool: If True (the default), copy the underlying data array. Otherwise, use the same data array. The meta is always deepcopied regardless of the value for copy_data.

field(item)¶: Return column[item] for recarray compatibility.

filled(fill_value=None)¶

Return copy of self, with masked values filled.

If input fill_value supplied then that value is used for all masked entries in the table. Otherwise the individual fill_value defined for each table column is used.

Parameters

fill_valuestr: If supplied, this fill_value is used for all masked entries in the entire table.

Returns

filled_tableTable: New table with masked values filled

classmethod from_pandas(dataframe, index=False)¶

Create a Table from a pandas.DataFrame instance

In addition to converting generic numeric or string columns, this supports conversion of pandas Date and Time delta columns to Time and TimeDelta columns, respectively.

Parameters

dataframepandas.DataFrame: A pandas pandas.DataFrame instance
indexbool: Include the index column in the returned table (default=False)

Returns

tableTable: A Table (or subclass) instance

Raises

ImportError: If pandas is not installed

Examples

Here we convert a pandas.DataFrame instance to a QTable.

>>> import numpy as np
>>> import pandas as pd
>>> from astropy.table import QTable

>>> time = pd.Series(['1998-01-01', '2002-01-01'], dtype='datetime64[ns]')
>>> dt = pd.Series(np.array([1, 300], dtype='timedelta64[s]'))
>>> df = pd.DataFrame({'time': time})
>>> df['dt'] = dt
>>> df['x'] = [3., 4.]
>>> with pd.option_context('display.max_columns', 20):
...     print(df)
        time       dt    x
0 1998-01-01 00:00:01  3.0
1 2002-01-01 00:05:00  4.0

>>> QTable.from_pandas(df)
<QTable length=2>
          time            dt      x
         object         object float64
----------------------- ------ -------
1998-01-01T00:00:00.000    1.0     3.0
2002-01-01T00:00:00.000  300.0     4.0

get_obs_idx(obs_id)[source]¶

Get row index for given obs_id.

Raises KeyError if observation is not available.

Parameters

obs_idint, list: observation ids

Returns

idxlist: indices corresponding to obs_id

group_by(keys)¶

Group this table by the specified keys

This effectively splits the table into groups which correspond to unique values of the keys grouping object. The output is a new TableGroups which contains a copy of this table but sorted by row according to keys.

The keys input to group_by can be specified in different ways:

String or list of strings corresponding to table column name(s)

Numpy array (homogeneous or structured) with same length as this table

Table with same length as this table

Parameters

keysstr, list of str, numpy array, or Table: Key grouping object

Returns

outTable: New table with groups set

index_column(name)¶

Return the positional index of column name.

Parameters

namestr: column name

Returns

indexint: Positional index of column name.

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3], ['x', 'y', 'z']],
...           names=('a', 'b', 'c'))
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y
  3 0.3   z

Get index of column ‘b’ of the table:

>>> t.index_column('b')
1

index_mode(mode)¶

Return a context manager for an indexing mode.

Parameters

modestr: Either ‘freeze’, ‘copy_on_getitem’, or ‘discard_on_copy’. In ‘discard_on_copy’ mode, indices are not copied whenever columns or tables are copied. In ‘freeze’ mode, indices are not modified whenever columns are modified; at the exit of the context, indices refresh themselves based on column values. This mode is intended for scenarios in which one intends to make many additions or modifications in an indexed column. In ‘copy_on_getitem’ mode, indices are copied when taking column slices as well as table slices, so col[i0:i1] will preserve indices.

insert_row(index, vals=None, mask=None)¶

Add a new row before the given index position in the table.

The vals argument can be:

sequence (e.g. tuple or list): Column values in the same order as table columns.
mapping (e.g. dict): Keys corresponding to column names. Missing values will be filled with np.zeros for the column dtype.
None: All values filled with np.zeros for the column dtype.

The mask attribute should give (if desired) the mask for the values. The type of the mask should match that of the values, i.e. if vals is an iterable, then mask should also be an iterable with the same length, and if vals is a mapping, then mask should be a dictionary.

Parameters

valstuple, list, dict or None: Use the specified values in the new row
masktuple, list, dict or None: Use the specified mask values in the new row

itercols()¶

Iterate over the columns of this table.

Examples

To iterate over the columns of a table:

>>> t = Table([[1], [2]])
>>> for col in t.itercols():
...     print(col)
col0
----
   1
col1
----
   2

Using itercols() is similar to for col in t.columns.values() but is syntactically preferred.

iterrows(*names)¶

Iterate over rows of table returning a tuple of values for each row.

This method is especially useful when only a subset of columns are needed.

The iterrows method can be substantially faster than using the standard Table row iteration (e.g. for row in tbl:), since that returns a new ~astropy.table.Row object for each row and accessing a column in that row (e.g. row['col0']) is slower than tuple access.

Parameters

nameslist: List of column names (default to all columns if no names provided)

Returns

rowsiterator returning tuples of row values

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table({'a': [1, 2, 3],
...            'b': [1.0, 2.5, 3.0],
...            'c': ['x', 'y', 'z']})

To iterate row-wise using column names:

>>> for a, c in t.iterrows('a', 'c'):
...     print(a, c)
1 x
2 y
3 z

keep_columns(names)¶

Keep only the columns specified (remove the others).

Parameters

nameslist: A list containing the names of the columns to keep. All other columns will be removed.

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1, 2, 3],[0.1, 0.2, 0.3],['x', 'y', 'z']],
...           names=('a', 'b', 'c'))
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y
  3 0.3   z

Specifying only a single column name keeps only this column. Keep only column ‘a’ of the table:

>>> t.keep_columns('a')
>>> print(t)
 a
---
  1
  2
  3

Specifying a list of column names is keeps is also possible. Keep columns ‘a’ and ‘c’ of the table:

>>> t = Table([[1, 2, 3],[0.1, 0.2, 0.3],['x', 'y', 'z']],
...           names=('a', 'b', 'c'))
>>> t.keep_columns(['a', 'c'])
>>> print(t)
 a   c
--- ---
  1   x
  2   y
  3   z

keys()¶

more(max_lines=None, max_width=None, show_name=True, show_unit=None, show_dtype=False)¶

Interactively browse table 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_linesint: Maximum number of lines in table output
max_widthint or None: Maximum character width of output
show_namebool: Include a header row for column names. Default is True.
show_unitbool: Include a header row for unit. Default is to show a row for units only if one or more columns has a defined value for the unit.
show_dtypebool: Include a header row for column dtypes. Default is True.

pformat(max_lines=None, max_width=None, show_name=True, show_unit=None, show_dtype=False, html=False, tableid=None, align=None, tableclass=None)¶

Return a list of lines for the formatted string representation of

the table.

If no value of max_lines is supplied then the height of the screen terminal is used to set max_lines. If the terminal height cannot be determined then the default is taken from the configuration item astropy.conf.max_lines. If a negative value of max_lines is supplied then there is no line limit applied.

The same applies for max_width except the configuration item is astropy.conf.max_width.

Parameters

max_linesint or None: Maximum number of rows to output
max_widthint or None: Maximum character width of output
show_namebool: Include a header row for column names. Default is True.
show_unitbool: Include a header row for unit. Default is to show a row for units only if one or more columns has a defined value for the unit.
show_dtypebool: Include a header row for column dtypes. Default is True.
htmlbool: Format the output as an HTML table. Default is False.
tableidstr or None: An ID tag for the table; only used if html is set. Default is “table{id}”, where id is the unique integer id of the table object, id(self)
alignstr or list or tuple or None: Left/right alignment of columns. Default is right (None) for all columns. Other allowed values are ‘>’, ‘<’, ‘^’, and ‘0=’ for right, left, centered, and 0-padded, respectively. A list of strings can be provided for alignment of tables with multiple columns.
tableclassstr or list of str or None: CSS classes for the table; only used if html is set. Default is None.

Returns

lineslist: Formatted table as a list of strings.

pformat_all(max_lines=-1, max_width=-1, show_name=True, show_unit=None, show_dtype=False, html=False, tableid=None, align=None, tableclass=None)¶

Return a list of lines for the formatted string representation of

the entire table.

If no value of max_lines is supplied then the height of the screen terminal is used to set max_lines. If the terminal height cannot be determined then the default is taken from the configuration item astropy.conf.max_lines. If a negative value of max_lines is supplied then there is no line limit applied.

The same applies for max_width except the configuration item is astropy.conf.max_width.

Parameters

max_linesint or None: Maximum number of rows to output
max_widthint or None: Maximum character width of output
show_namebool: Include a header row for column names. Default is True.
show_unitbool: Include a header row for unit. Default is to show a row for units only if one or more columns has a defined value for the unit.
show_dtypebool: Include a header row for column dtypes. Default is True.
htmlbool: Format the output as an HTML table. Default is False.
tableidstr or None: An ID tag for the table; only used if html is set. Default is “table{id}”, where id is the unique integer id of the table object, id(self)
alignstr or list or tuple or None: Left/right alignment of columns. Default is right (None) for all columns. Other allowed values are ‘>’, ‘<’, ‘^’, and ‘0=’ for right, left, centered, and 0-padded, respectively. A list of strings can be provided for alignment of tables with multiple columns.
tableclassstr or list of str or None: CSS classes for the table; only used if html is set. Default is None.

Returns

lineslist: Formatted table as a list of strings.

pprint(max_lines=None, max_width=None, show_name=True, show_unit=None, show_dtype=False, align=None)¶

Print a formatted string representation of the table.

If no value of max_lines is supplied then the height of the screen terminal is used to set max_lines. If the terminal height cannot be determined then the default is taken from the configuration item astropy.conf.max_lines. If a negative value of max_lines is supplied then there is no line limit applied.

The same applies for max_width except the configuration item is astropy.conf.max_width.

Parameters

max_linesint or None: Maximum number of lines in table output.
max_widthint or None: Maximum character width of output.
show_namebool: Include a header row for column names. Default is True.
show_unitbool: Include a header row for unit. Default is to show a row for units only if one or more columns has a defined value for the unit.
show_dtypebool: Include a header row for column dtypes. Default is True.
alignstr or list or tuple or None: Left/right alignment of columns. Default is right (None) for all columns. Other allowed values are ‘>’, ‘<’, ‘^’, and ‘0=’ for right, left, centered, and 0-padded, respectively. A list of strings can be provided for alignment of tables with multiple columns.

pprint_all(max_lines=-1, max_width=-1, show_name=True, show_unit=None, show_dtype=False, align=None)¶

Print a formatted string representation of the entire table.

This method is the same as astropy.table.Table.pprint except that the default max_lines and max_width are both -1 so that by default the entire table is printed instead of restricting to the size of the screen terminal.

Parameters

max_linesint or None: Maximum number of lines in table output.
max_widthint or None: Maximum character width of output.
show_namebool: Include a header row for column names. Default is True.
show_unitbool: Include a header row for unit. Default is to show a row for units only if one or more columns has a defined value for the unit.
show_dtypebool: Include a header row for column dtypes. Default is True.
alignstr or list or tuple or None: Left/right alignment of columns. Default is right (None) for all columns. Other allowed values are ‘>’, ‘<’, ‘^’, and ‘0=’ for right, left, centered, and 0-padded, respectively. A list of strings can be provided for alignment of tables with multiple columns.

classmethod read(filename, **kwargs)[source]¶

Read an observation table from file.

Parameters

filenamepathlib.Path, str: Filename

remove_column(name)¶

Remove a column from the table.

This can also be done with:

del table[name]

Parameters

namestr: Name of column to remove

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3], ['x', 'y', 'z']],
...           names=('a', 'b', 'c'))
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y
  3 0.3   z

Remove column ‘b’ from the table:

>>> t.remove_column('b')
>>> print(t)
 a   c
--- ---
  1   x
  2   y
  3   z

To remove several columns at the same time use remove_columns.

remove_columns(names)¶

Remove several columns from the table.

Parameters

nameslist: A list containing the names of the columns to remove

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3], ['x', 'y', 'z']],
...     names=('a', 'b', 'c'))
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y
  3 0.3   z

Remove columns ‘b’ and ‘c’ from the table:

>>> t.remove_columns(['b', 'c'])
>>> print(t)
 a
---
  1
  2
  3

Specifying only a single column also works. Remove column ‘b’ from the table:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3], ['x', 'y', 'z']],
...     names=('a', 'b', 'c'))
>>> t.remove_columns('b')
>>> print(t)
 a   c
--- ---
  1   x
  2   y
  3   z

This gives the same as using remove_column.

remove_indices(colname)¶

Remove all indices involving the given column. If the primary index is removed, the new primary index will be the most recently added remaining index.

Parameters

colnamestr: Name of column

remove_row(index)¶

Remove a row from the table.

Parameters

indexint: Index of row to remove

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3], ['x', 'y', 'z']],
...           names=('a', 'b', 'c'))
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y
  3 0.3   z

Remove row 1 from the table:

>>> t.remove_row(1)
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  3 0.3   z

To remove several rows at the same time use remove_rows.

remove_rows(row_specifier)¶

Remove rows from the table.

Parameters

row_specifierslice, int, or array of ints: Specification for rows to remove

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3], ['x', 'y', 'z']],
...           names=('a', 'b', 'c'))
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y
  3 0.3   z

Remove rows 0 and 2 from the table:

>>> t.remove_rows([0, 2])
>>> print(t)
 a   b   c
--- --- ---
  2 0.2   y

Note that there are no warnings if the slice operator extends outside the data:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3], ['x', 'y', 'z']],
...           names=('a', 'b', 'c'))
>>> t.remove_rows(slice(10, 20, 1))
>>> print(t)
 a   b   c
--- --- ---
  1 0.1   x
  2 0.2   y
  3 0.3   z

rename_column(name, new_name)¶

Rename a column.

This can also be done directly with by setting the name attribute for a column:

table[name].name = new_name

TODO: this won’t work for mixins

Parameters

namestr: The current name of the column.
new_namestr: The new name for the column

Examples

Create a table with three columns ‘a’, ‘b’ and ‘c’:

>>> t = Table([[1,2],[3,4],[5,6]], names=('a','b','c'))
>>> print(t)
 a   b   c
--- --- ---
  1   3   5
  2   4   6

Renaming column ‘a’ to ‘aa’:

>>> t.rename_column('a' , 'aa')
>>> print(t)
 aa  b   c
--- --- ---
  1   3   5
  2   4   6

rename_columns(names, new_names)¶

Rename multiple columns.

Parameters

nameslist, tuple: A list or tuple of existing column names.
new_nameslist, tuple: A list or tuple of new column names.

Examples

Create a table with three columns ‘a’, ‘b’, ‘c’:

>>> t = Table([[1,2],[3,4],[5,6]], names=('a','b','c'))
>>> print(t)
  a   b   c
 --- --- ---
  1   3   5
  2   4   6

Renaming columns ‘a’ to ‘aa’ and ‘b’ to ‘bb’:

>>> names = ('a','b')
>>> new_names = ('aa','bb')
>>> t.rename_columns(names, new_names)
>>> print(t)
 aa  bb   c
--- --- ---
  1   3   5
  2   4   6

replace_column(name, col, copy=True)¶

Replace column name with the new col object.

The behavior of copy for Column objects is: - copy=True: new class instance with a copy of data and deep copy of meta - copy=False: new class instance with same data and a key-only copy of meta

For mixin columns: - copy=True: new class instance with copy of data and deep copy of meta - copy=False: original instance (no copy at all)

Parameters

namestr: Name of column to replace
colcolumn object (list, ndarray, Column, etc): New column object to replace the existing column
copybool: Make copy of the input col, default=True

Examples

Replace column ‘a’ with a float version of itself:

>>> t = Table([[1, 2, 3], [0.1, 0.2, 0.3]], names=('a', 'b'))
>>> float_a = t['a'].astype(float)
>>> t.replace_column('a', float_a)

reverse()¶

Reverse the row order of table rows. The table is reversed in place and there are no function arguments.

Examples

Create a table with three columns:

>>> t = Table([['Max', 'Jo', 'John'], ['Miller','Miller','Jackson'],
...         [12,15,18]], names=('firstname','name','tel'))
>>> print(t)
firstname   name  tel
--------- ------- ---
      Max  Miller  12
       Jo  Miller  15
     John Jackson  18

Reversing order:

>>> t.reverse()
>>> print(t)
firstname   name  tel
--------- ------- ---
     John Jackson  18
       Jo  Miller  15
      Max  Miller  12

select_obs_id(obs_id)[source]¶

Get ObservationTable containing only obs_id.

Raises KeyError if observation is not available.

Parameters

obs_id: int, list: observation ids

select_observations(selection=None)[source]¶

Select subset of observations.

Returns a new observation table representing the subset.

There are 3 main kinds of selection criteria, according to the value of the type keyword in the selection dictionary:

sky regions
time intervals (min, max)
intervals (min, max) on any other parameter present in the observation table, that can be casted into an Quantity object

Allowed selection criteria are interpreted using the following keywords in the selection dictionary under the type key.

sky_circle is a circular region centered in the coordinate
marked by the lon and lat keywords, and radius radius; uses select_sky_circle
time_box is a 1D selection criterion acting on the observation start time (TSTART); the interval is set via the time_range keyword; uses select_time_range
par_box is a 1D selection criterion acting on any parameter defined in the observation table that can be casted into an Quantity object; the parameter name and interval can be specified using the keywords variable and value_range respectively; min = max selects exact values of the parameter; uses select_range

In all cases, the selection can be inverted by activating the inverted flag, in which case, the selection is applied to keep all elements outside the selected range.

A few examples of selection criteria are given below.

Parameters

selectiondict: Dictionary with a few keywords for applying selection cuts.

Returns

obs_tableObservationTable: Observation table after selection.

Examples

>>> selection = dict(type='sky_circle', frame='galactic',
...                  lon=Angle(0, 'deg'),
...                  lat=Angle(0, 'deg'),
...                  radius=Angle(5, 'deg'),
...                  border=Angle(2, 'deg'))
>>> selected_obs_table = obs_table.select_observations(selection)

>>> selection = dict(type='time_box',
...                  time_range=Time(['2012-01-01T01:00:00', '2012-01-01T02:00:00']))
>>> selected_obs_table = obs_table.select_observations(selection)

>>> selection = dict(type='par_box', variable='ALT',
...                  value_range=Angle([60., 70.], 'deg'))
>>> selected_obs_table = obs_table.select_observations(selection)

>>> selection = dict(type='par_box', variable='OBS_ID',
...                  value_range=[2, 5])
>>> selected_obs_table = obs_table.select_observations(selection)

>>> selection = dict(type='par_box', variable='N_TELS',
...                  value_range=[4, 4])
>>> selected_obs_table = obs_table.select_observations(selection)

select_range(selection_variable, value_range, inverted=False)[source]¶

Make an observation table, applying some selection.

Generic function to apply a 1D box selection (min, max) to a table on any variable that is in the observation table and can be casted into a Quantity object.

If the range length is 0 (min = max), the selection is applied to the exact value indicated by the min value. This is useful for selection of exact values, for instance in discrete variables like the number of telescopes.

If the inverted flag is activated, the selection is applied to keep all elements outside the selected range.

Parameters

selection_variablestr: Name of variable to apply a cut (it should exist on the table).
value_rangeQuantity-like: Allowed range of values (min, max). The type should be consistent with the selection_variable.
invertedbool, optional: Invert selection: keep all entries outside the (min, max) range.

Returns

obs_tableObservationTable: Observation table after selection.

select_time_range(time_range, partial_overlap=False, inverted=False)[source]¶

Make an observation table, applying a time selection.

Apply a 1D box selection (min, max) to a table on any time variable that is in the observation table. It supports absolute times in Time format.

If the inverted flag is activated, the selection is applied to keep all elements outside the selected range.

Parameters

time_rangeTime: Allowed time range (min, max).
partial_overlapbool, optional: Include partially overlapping observations. Default is False
invertedbool, optional: Invert selection: keep all entries outside the (min, max) range.

Returns

obs_tableObservationTable: Observation table after selection.

show_in_browser(max_lines=5000, jsviewer=False, browser='default', jskwargs={'use_local_files': True}, tableid=None, table_class='display compact', css=None, show_row_index='idx')¶

Render the table in HTML and show it in a web browser.

Parameters

max_linesint: Maximum number of rows to export to the table (set low by default to avoid memory issues, since the browser view requires duplicating the table in memory). A negative value of max_lines indicates no row limit.
jsviewerbool: If True, prepends some javascript headers so that the table is rendered as a DataTables data table. This allows in-browser searching & sorting.
browserstr: Any legal browser name, e.g. 'firefox', 'chrome', 'safari' (for mac, you may need to use 'open -a "/Applications/Google Chrome.app" {}' for Chrome). If 'default', will use the system default browser.
jskwargsdict: Passed to the astropy.table.JSViewer init. Defaults to {'use_local_files': True} which means that the JavaScript libraries will be served from local copies.
tableidstr or None: An html ID tag for the table. Default is table{id}, where id is the unique integer id of the table object, id(self).
table_classstr or None: A string with a list of HTML classes used to style the table. Default is “display compact”, and other possible values can be found in https://www.datatables.net/manual/styling/classes
cssstr: A valid CSS string declaring the formatting for the table. Defaults to astropy.table.jsviewer.DEFAULT_CSS.
show_row_indexstr or False: If this does not evaluate to False, a column with the given name will be added to the version of the table that gets displayed. This new column shows the index of the row in the table itself, even when the displayed table is re-sorted by another column. Note that if a column with this name already exists, this option will be ignored. Defaults to “idx”.

show_in_notebook(tableid=None, css=None, display_length=50, table_class='astropy-default', show_row_index='idx')¶

Render the table in HTML and show it in the IPython notebook.

Parameters

tableidstr or None: An html ID tag for the table. Default is table{id}-XXX, where id is the unique integer id of the table object, id(self), and XXX is a random number to avoid conflicts when printing the same table multiple times.
table_classstr or None: A string with a list of HTML classes used to style the table. The special default string (‘astropy-default’) means that the string will be retrieved from the configuration item astropy.table.default_notebook_table_class. Note that these table classes may make use of bootstrap, as this is loaded with the notebook. See this page for the list of classes.
cssstr: A valid CSS string declaring the formatting for the table. Defaults to astropy.table.jsviewer.DEFAULT_CSS_NB.
display_lengthint, optional: Number or rows to show. Defaults to 50.
show_row_indexstr or False: If this does not evaluate to False, a column with the given name will be added to the version of the table that gets displayed. This new column shows the index of the row in the table itself, even when the displayed table is re-sorted by another column. Note that if a column with this name already exists, this option will be ignored. Defaults to “idx”.

Notes

Currently, unlike show_in_browser (with jsviewer=True), this method needs to access online javascript code repositories. This is due to modern browsers’ limitations on accessing local files. Hence, if you call this method while offline (and don’t have a cached version of jquery and jquery.dataTables), you will not get the jsviewer features.

sort(keys=None, reverse=False)¶

Sort the table according to one or more keys. This operates on the existing table and does not return a new table.

Parameters

keysstr or list of str: The key(s) to order the table by. If None, use the primary index of the Table.
reversebool: Sort in reverse order (default=False)

Examples

Create a table with 3 columns:

>>> t = Table([['Max', 'Jo', 'John'], ['Miller', 'Miller', 'Jackson'],
...            [12, 15, 18]], names=('firstname', 'name', 'tel'))
>>> print(t)
firstname   name  tel
--------- ------- ---
      Max  Miller  12
       Jo  Miller  15
     John Jackson  18

Sorting according to standard sorting rules, first ‘name’ then ‘firstname’:

>>> t.sort(['name', 'firstname'])
>>> print(t)
firstname   name  tel
--------- ------- ---
     John Jackson  18
       Jo  Miller  15
      Max  Miller  12

Sorting according to standard sorting rules, first ‘firstname’ then ‘tel’, in reverse order:

>>> t.sort(['firstname', 'tel'], reverse=True)
>>> print(t)
firstname   name  tel
--------- ------- ---
      Max  Miller  12
     John Jackson  18
       Jo  Miller  15

summary()[source]¶: Summary info string (str).

to_pandas(index=None)¶

Return a pandas.DataFrame instance

The index of the created DataFrame is controlled by the index argument. For index=True or the default None, an index will be specified for the DataFrame if there is a primary key index on the Table and if it corresponds to a single column. If index=False then no DataFrame index will be specified. If index is the name of a column in the table then that will be the DataFrame index.

In additional to vanilla columns or masked columns, this supports Table mixin columns like Quantity, Time, or SkyCoord. In many cases these objects have no analog in pandas and will be converted to a “encoded” representation using only Column or MaskedColumn. The exception is Time or TimeDelta columns, which will be converted to the corresponding representation in pandas using np.datetime64 or np.timedelta64. See the example below.

Returns

dataframepandas.DataFrame: A pandas pandas.DataFrame instance
indexNone, bool, str: Specify DataFrame index mode

Raises

ImportError: If pandas is not installed
ValueError: If the Table has multi-dimensional columns

Examples

Here we convert a table with a few mixins to a pandas.DataFrame instance.

>>> import pandas as pd
>>> from astropy.table import QTable
>>> import astropy.units as u
>>> from astropy.time import Time, TimeDelta
>>> from astropy.coordinates import SkyCoord

>>> q = [1, 2] * u.m
>>> tm = Time([1998, 2002], format='jyear')
>>> sc = SkyCoord([5, 6], [7, 8], unit='deg')
>>> dt = TimeDelta([3, 200] * u.s)

>>> t = QTable([q, tm, sc, dt], names=['q', 'tm', 'sc', 'dt'])

>>> df = t.to_pandas(index='tm')
>>> with pd.option_context('display.max_columns', 20):
...     print(df)
              q  sc.ra  sc.dec       dt
tm
1998-01-01  1.0    5.0     7.0 00:00:03
2002-01-01  2.0    6.0     8.0 00:03:20

values_equal(other)¶

Element-wise comparison of table with another table, list, or scalar.

Returns a Table with the same columns containing boolean values showing result of comparison.

Parameters

otherTable-like object or list or scalar: Object to compare with table

Examples

Compare one Table with other:

>>> t1 = Table([[1, 2], [4, 5], [-7, 8]], names=('a', 'b', 'c'))
>>> t2 = Table([[1, 2], [-4, 5], [7, 8]], names=('a', 'b', 'c'))
>>> t1.values_equal(t2)
<Table length=2>
 a     b     c
bool  bool  bool
---- ----- -----
True False False
True  True  True