Examples

Building a table

Making a table is trivial:

>>> from toytable import Table
>>> p = Table([('Owner Id', int), 'Pokemon', ('Level', int)])
>>> p.extend([
...     [1, 'Pikachu', 18],
...     [1, 'Bulbasaur', 22],
...     [1, 'Charmander', 12],
...     [3, 'Togepi', 5],
...     [1, 'Starmie', 44],
...     [9, 'Mew', 99],
... ])

Printing tables

Table objects can be printed:

>>> print p
| Owner Id (int) | Pokemon    | Level (int) |
| 1              | Pikachu    | 18          |
| 1              | Bulbasaur  | 22          |
| 1              | Charmander | 12          |
| 3              | Togepi     | 5           |
| 1              | Starmie    | 44          |
| 9              | Mew        | 99          |

Appending to tables

You can add data to Tables one row at a time. It has the same effect as using the Table.extend(iter) function:

>>> o = Table([('Owner Id', int), ('Name', str)])
>>> o.append([1, 'Ash Ketchum'])
>>> o.append([2, 'Brock'])
>>> o.append([3, 'Misty'])
>>> print o
| Owner Id (int) | Name (str)  |
| 1              | Ash Ketchum |
| 2              | Brock       |
| 3              | Misty       |

Joins on tables

Tables can be joined to other Tables:

>>> j = p.left_join(
...     keys=('Owner Id',),
...     other = o
... )
>>> print j
| Owner Id (int) | Pokemon    | Level (int) | Name (str)  |
| 1              | Pikachu    | 18          | Ash Ketchum |
| 1              | Bulbasaur  | 22          | Ash Ketchum |
| 1              | Charmander | 12          | Ash Ketchum |
| 3              | Togepi     | 5           | Misty       |
| 1              | Starmie    | 44          | Ash Ketchum |
| 9              | Mew        | 99          | None        |

Re-ordering columns

The project method allows you to re-order and remove columns from a Table:

>>> j2 = j.project('Pokemon', 'Level', 'Name')
>>> print j2
| Pokemon    | Level (int) | Name (str)  |
| Pikachu    | 18          | Ash Ketchum |
| Bulbasaur  | 22          | Ash Ketchum |
| Charmander | 12          | Ash Ketchum |
| Togepi     | 5           | Misty       |
| Starmie    | 44          | Ash Ketchum |
| Mew        | 99          | None        |

Filtering rows of a table

The restrict method allows basic filtering of a Table:

>>> restricted = j2.restrict(['Name'], lambda n: n == 'Ash Ketchum')
>>> print restricted
| Pokemon    | Level (int) | Name (str)  |
| Pikachu    | 18          | Ash Ketchum |
| Bulbasaur  | 22          | Ash Ketchum |
| Charmander | 12          | Ash Ketchum |
| Starmie    | 44          | Ash Ketchum |

Slicing Operations

Tables can also be sliced - and do exactly what you’d expect:

>>> sliced = j2[1:-1]
>>> print sliced
| Pokemon    | Level (int) | Name (str)  |
| Bulbasaur  | 22          | Ash Ketchum |
| Charmander | 12          | Ash Ketchum |
| Togepi     | 5           | Misty       |
| Starmie    | 44          | Ash Ketchum |

Copying tables

Tables can be copied - that flattens their internal structure and can result in improved performance:

>>> j3 = j2.copy()

Flattened Tables (but currently not DerivedTables) can be indexed. Indexes can be used to quickly look up rows by part of their value. Indexes eliminate the need for time-consuming search operations:

>>> i = j3.add_index(('Pokemon',)).reindex()
>>> print i[('Pikachu', )]
('Pikachu', 18, 'Ash Ketchum')