Source code for astropy.table.row

# Licensed under a 3-clause BSD style license - see LICENSE.rst

import collections
from collections import OrderedDict
from operator import index as operator_index

import numpy as np

[docs]class Row: """A class to represent one row of a Table object. A Row object is returned when a Table object is indexed with an integer or when iterating over a table:: >>> from astropy.table import Table >>> table = Table([(1, 2), (3, 4)], names=('a', 'b'), ... dtype=('int32', 'int32')) >>> row = table[1] >>> row <Row index=1> a b int32 int32 ----- ----- 2 4 >>> row['a'] 2 >>> row[1] 4 """ def __init__(self, table, index): # Ensure that the row index is a valid index (int) index = operator_index(index) n = len(table) if index < -n or index >= n: raise IndexError('index {} out of range for table with length {}' .format(index, len(table))) # Finally, ensure the index is positive [#8422] and set Row attributes self._index = index % n self._table = table def __getitem__(self, item): try: # Try the most common use case of accessing a single column in the Row. # Bypass the TableColumns __getitem__ since that does more testing # and allows a list of tuple or str, which is not the right thing here. out = OrderedDict.__getitem__(self._table.columns, item)[self._index] except (KeyError, TypeError): if self._table._is_list_or_tuple_of_str(item): cols = [self._table[name] for name in item] out = self._table.__class__(cols, copy=False)[self._index] else: # This is only to raise an exception out = self._table.columns[item][self._index] return out def __setitem__(self, item, val): if self._table._is_list_or_tuple_of_str(item): self._table._set_row(self._index, colnames=item, vals=val) else: self._table.columns[item][self._index] = val def _ipython_key_completions_(self): return self.colnames def __eq__(self, other): if self._table.masked: # Sent bug report to numpy-discussion group on 2012-Oct-21, subject: # "Comparing rows in a structured masked array raises exception" # No response, so this is still unresolved. raise ValueError('Unable to compare rows for masked table due to bug') return self.as_void() == other def __ne__(self, other): if self._table.masked: raise ValueError('Unable to compare rows for masked table due to bug') return self.as_void() != other def __array__(self, dtype=None): """Support converting Row to np.array via np.array(table). Coercion to a different dtype via np.array(table, dtype) is not supported and will raise a ValueError. If the parent table is masked then the mask information is dropped. """ if dtype is not None: raise ValueError('Datatype coercion is not allowed') return np.asarray(self.as_void()) def __len__(self): return len(self._table.columns) def __iter__(self): index = self._index for col in self._table.columns.values(): yield col[index]
[docs] def keys(self): return self._table.columns.keys()
[docs] def values(self): return self.__iter__()
@property def table(self): return self._table @property def index(self): return self._index
[docs] def as_void(self): """ Returns a *read-only* copy of the row values in the form of np.void or objects. This corresponds to the object types returned for row indexing of a pure numpy structured array or masked array. This method is slow and its use is discouraged when possible. Returns ------- void_row : ``numpy.void`` or ```` Copy of row values. ``numpy.void`` if unmasked, ```` else. """ index = self._index cols = self._table.columns.values() vals = tuple(np.asarray(col)[index] for col in cols) if self._table.masked: mask = tuple(col.mask[index] if hasattr(col, 'mask') else False for col in cols) void_row =[vals], mask=[mask], dtype=self.dtype)[0] else: void_row = np.array([vals], dtype=self.dtype)[0] return void_row
@property def meta(self): return self._table.meta @property def columns(self): return self._table.columns @property def colnames(self): return self._table.colnames @property def dtype(self): return self._table.dtype def _base_repr_(self, html=False): """ Display row as a single-line table but with appropriate header line. """ index = self.index if (self.index >= 0) else self.index + len(self._table) table = self._table[index:index + 1] descr_vals = [self.__class__.__name__, f'index={self.index}'] if table.masked: descr_vals.append('masked=True') return table._base_repr_(html, descr_vals, max_width=-1, tableid=f'table{id(self._table)}') def _repr_html_(self): return self._base_repr_(html=True) def __repr__(self): return self._base_repr_(html=False) def __str__(self): index = self.index if (self.index >= 0) else self.index + len(self._table) return '\n'.join(self.table[index:index + 1].pformat(max_width=-1)) def __bytes__(self): return str(self).encode('utf-8')