deephaven.table_listener¶
This module provides utilities for listening to table changes.
- class TableListener[source]¶
Bases:
abc.ABC
An abstract table listener class that should be subclassed by any user table listener class.
- class TableListenerHandle(t, listener, description=None)[source]¶
Bases:
object
A handle to manage a table listener’s lifecycle.
- start(do_replay=False, replay_lock='shared')[source]¶
Start the listener by registering it with the table and listening for updates.
- Parameters
do_replay (bool) – whether to replay the initial snapshot of the table, default is False
replay_lock (str) – the lock type used during replay, default is ‘shared’, can also be ‘exclusive’.
- Raises
DHError –
- Return type
None
- class TableUpdate(table, j_table_update)[source]¶
Bases:
deephaven._wrapper.JObjectWrapper
- added(cols=None)[source]¶
Returns a dict with each key being a column name and each value being a NumPy array of all the added rows in the columns.
- Parameters
cols (Union[str, List[str]) – the column(s) for which to return the added rows
- Return type
Dict
[str
,ndarray
]- Returns
a dict
- added_chunks(chunk_size, cols=None)[source]¶
Returns a generator that on each iteration, only returns a chunk of added rows in the form of a dict with each key being a column name and each value being a NumPy array of the rows in the chunk.
- Parameters
chunk_size (int) – the size of the chunk
(Union[str (cols) – the columns(s) for which to return the added rows
List[str]] – the columns(s) for which to return the added rows
- Return type
Generator
[Dict
[str
,ndarray
],None
,None
]- Returns
a generator
- j_object_type¶
alias of
io.deephaven.engine.table.TableUpdate
- modified(cols=None)[source]¶
Returns a dict with each key being a column name and each value being a NumPy array of the current values of all the modified rows in the columns.
- Parameters
cols (Union[str, List[str]) – the column(s) for which to return the added rows
- Return type
Dict
[str
,ndarray
]- Returns
a dict
- modified_chunks(chunk_size, cols=None)[source]¶
Returns a generator that on each iteration, only returns a chunk of modified rows in the form of a dict with each key being a column name and each value being a NumPy array of the current values of the rows in the chunk.
- Parameters
chunk_size (int) – the size of the chunk
(Union[str (cols) – the columns(s) for which to return the added rows
List[str]] – the columns(s) for which to return the added rows
- Return type
Generator
[Dict
[str
,ndarray
],None
,None
]- Returns
a generator
- property modified_columns¶
The list of modified columns in this update.
- modified_prev(cols=None)[source]¶
Returns a dict with each key being a column name and each value being a NumPy array of the previous values of all the modified rows in the columns.
- Parameters
cols (Union[str, List[str]) – the column(s) for which to return the added rows
- Return type
Dict
[str
,ndarray
]- Returns
a dict
- modified_prev_chunks(chunk_size, cols=None)[source]¶
Returns a generator that on each iteration, only returns a chunk of modified rows in the form of a dict with each key being a column name and each value being a NumPy array of the previous values of the rows in the chunk.
- Parameters
chunk_size (int) – the size of the chunk
(Union[str (cols) – the columns(s) for which to return the added rows
List[str]] – the columns(s) for which to return the added rows
- Return type
Generator
[Dict
[str
,ndarray
],None
,None
]- Returns
a generator
- removed(cols=None)[source]¶
Returns a dict with each key being a column name and each value being a NumPy array of all the removed rows in the columns.
- Parameters
cols (Union[str, List[str]) – the column(s) for which to return the added rows
- Return type
Dict
[str
,ndarray
]- Returns
a dict
- removed_chunks(chunk_size, cols=None)[source]¶
Returns a generator that on each iteration, only returns a chunk of removed rows in the form of a dict with each key being a column name and each value being a NumPy array of the rows in the chunk.
- Parameters
chunk_size (int) – the size of the chunk
(Union[str (cols) – the columns(s) for which to return the added rows
List[str]] – the columns(s) for which to return the added rows
- Return type
Generator
[Dict
[str
,ndarray
],None
,None
]- Returns
a generator
- listen(t, listener, description=None, do_replay=False, replay_lock='shared')[source]¶
This is a convenience function that creates a TableListenerHandle object and immediately starts it to listen for table updates.
The function returns the created TableListenerHandle object whose ‘stop’ method can be called to stop listening. If it goes out of scope and is garbage collected, the listener will stop receiving any table updates.
- Parameters
t (Table) – table to listen to
listener (Union[Callable, TableListener]) – listener for table changes
description (str, optional) – description for the UpdatePerformanceTracker to append to the listener’s entry description, default is None
do_replay (bool) – whether to replay the initial snapshot of the table, default is False
replay_lock (str) – the lock type used during replay, default is ‘shared’, can also be ‘exclusive’
- Returns
a TableListenerHandle
- Raises
DHError –