unique

astropy.table.unique(input_table, keys=None, silent=False, keep='first')[source] [edit on github]

Returns the unique rows of a table.

Parameters:

input_table : Table object or a value that

will initialize a Table object

keys : str or list of str

Name(s) of column(s) used to create unique rows. Default is to use all columns.

keep : one of ‘first’, ‘last’ or ‘none’

Whether to keep the first or last row for each set of duplicates. If ‘none’, all rows that are duplicate are removed, leaving only rows that are already unique in the input. Default is ‘first’.

silent : boolean

If True, masked value column(s) are silently removed from keys. If False, an exception is raised when keys contains masked value column(s). Default is False.

Returns:

unique_table : Table object

New table containing only the unique rows of input_table.

Examples

>>> from astropy.table import unique, Table
>>> import numpy as np
>>> table = Table(data=[[1,2,3,2,3,3],
... [2,3,4,5,4,6],
... [3,4,5,6,7,8]],
... names=['col1', 'col2', 'col3'],
... dtype=[np.int32, np.int32, np.int32])
>>> table
<Table length=6>
 col1  col2  col3
int32 int32 int32
----- ----- -----
    1     2     3
    2     3     4
    3     4     5
    2     5     6
    3     4     7
    3     6     8
>>> unique(table, keys='col1')
<Table length=3>
 col1  col2  col3
int32 int32 int32
----- ----- -----
    1     2     3
    2     3     4
    3     4     5
>>> unique(table, keys=['col1'], keep='last')
<Table length=3>
 col1  col2  col3
int32 int32 int32
----- ----- -----
    1     2     3
    2     5     6
    3     6     8
>>> unique(table, keys=['col1', 'col2'])
<Table length=5>
 col1  col2  col3
int32 int32 int32
----- ----- -----
    1     2     3
    2     3     4
    2     5     6
    3     4     5
    3     6     8
>>> unique(table, keys=['col1', 'col2'], keep='none')
<Table length=4>
 col1  col2  col3
int32 int32 int32
----- ----- -----
    1     2     3
    2     3     4
    2     5     6
    3     6     8
>>> unique(table, keys=['col1'], keep='none')
<Table length=1>
 col1  col2  col3
int32 int32 int32
----- ----- -----
    1     2     3