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table.py
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173 lines (143 loc) · 4.46 KB
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"""
=============
Row tests
=============
>>> row = Row([1, 2, 3, 4])
>>> row[1]
2
>>> row[1:3]
Row([2, 3])
=============
Table tests
=============
Create an empty table
>>> t3x4 = Table.blank(3, 4)
>>> t3x4
Table(Row([None, None, None, None]),
Row([None, None, None, None]),
Row([None, None, None, None]))
>>> for i in range(3):
... for j in range(4):
... t3x4[i][j] = chr(65 + i * 4 + j)
...
>>> t3x4
Table(Row(['A', 'B', 'C', 'D']),
Row(['E', 'F', 'G', 'H']),
Row(['I', 'J', 'K', 'L']))
>>> t3x4[1]
Row(['E', 'F', 'G', 'H'])
>>> t3x4[1:]
Table(Row(['E', 'F', 'G', 'H']),
Row(['I', 'J', 'K', 'L']))
>>> t3x4[1][2]
'G'
>>> t3x4[1, 2]
'G'
Slicing returns a table, so index 2 below would be trying to get row index 2
of a table that has only rows 0 and 1:
>>> t3x4[1:][2]
Traceback (most recent call last):
...
IndexError: no row at index 2 of 2-row table
>>> t3x4[:, 2]
Table(Row(['C']),
Row(['G']),
Row(['K']))
>>> t3x4[1:, 2]
Table(Row(['G']),
Row(['K']))
>>> t3x4[1, 2:]
Row(['G', 'H'])
>>> t3x4[:, 1:3]
Table(Row(['B', 'C']),
Row(['F', 'G']),
Row(['J', 'K']))
>>> t3x4[:, :]
Table(Row(['A', 'B', 'C', 'D']),
Row(['E', 'F', 'G', 'H']),
Row(['I', 'J', 'K', 'L']))
>>> t3x4[:, :] == t3x4
True
===============
Error handling
===============
>>> t3x4[5]
Traceback (most recent call last):
...
IndexError: no row at index 5 of 3-row table
>>> t3x4[1,]
Traceback (most recent call last):
...
IndexError: index must be [i] or [i, j]
>>> t3x4[1, 2, 3]
Traceback (most recent call last):
...
IndexError: index must be [i] or [i, j]
>>> t3x4[10:, 2]
Traceback (most recent call last):
...
ValueError: Table must have at least one row.
>>> t3x4[1, 20:]
Traceback (most recent call last):
...
ValueError: Row must have at least one cell.
"""
import collections
class Row(collections.UserList):
def __init__(self, cells):
super().__init__(cells)
if len(self) < 1:
raise ValueError('Row must have at least one cell.')
def __getitem__(self, position):
if isinstance(position, slice):
return Row(self.data[position]) # build sub-row
else:
return self.data[position] # return cell value
def __repr__(self):
return '%s(%r)' % (self.__class__.__name__, self.data)
class Table(collections.UserList):
"""A table with rows, all of the same width"""
def __init__(self, rows):
super().__init__(Row(r) for r in rows)
if len(self) < 1:
raise ValueError('Table must have at least one row.')
self.width = self.check_width()
def check_width(self):
row_widths = {len(row) for row in self.data}
if len(row_widths) > 1:
raise ValueError('All rows must have equal length.')
return row_widths.pop()
@classmethod
def blank(class_, rows, columns, filler=None):
return class_([[filler] * columns for i in range(rows)])
def __repr__(self):
prefix = '%s(' % self.__class__.__name__
indent = ' ' * len(prefix)
rows = (',\n' + indent).join(
repr(row) for row in self.data)
return prefix + rows + ')'
def _get_indexes(self, position):
if isinstance(position, tuple): # multiple indexes
if len(position) == 2: # two indexes: t[i, j]
return position
else:
raise IndexError('index must be [i] or [i, j]')
else: # one index: t[i]
return position, None
def __getitem__(self, position):
i, j = self._get_indexes(position)
if isinstance(i, slice):
if j is None: # build sub-table w/ full rows
return Table(self.data[position])
else: # build sub-table w/ sub-rows
return Table(cells[j] for cells in self.data[i])
else: # i is number
try:
row = self.data[i]
except IndexError:
msg = 'no row at index %r of %d-row table'
raise IndexError(msg % (position, len(self)))
if j is None: # return row at table[i]
return row
else:
return row[j] # return row[j] or row[a:b]