Sequence management

The Entities' creation section provides documentation on Sequence creation. Now that we know how to create a new Sequence, this section focuses on describing the sequence's attributes and utility methods.

In this section, it is assumed that the my_config.py module contains an already implemented configuration.

Sequence attributes

A sequence is identified by a unique identifier id that Taipy generates. A sequence also holds various properties accessible as an attribute of the sequence:

add data_nodes, parent_ids

• subscribers: The list of Tuples (callback, params) representing the subscribers.
• properties: The complete dictionary of the sequence properties. It includes a copy of the properties of the sequence configuration, in addition to the properties provided at the creation and runtime.
• tasks: The dictionary holds the sequence's various tasks. The key corresponds to the config_id of the task while the value is the task itself.
• data_nodes: The dictionary holding the various data nodes of the sequence. The key corresponds to the data node's config_id (while the value is the data node itself).
• owner_id: The identifier of the owner, which can be a scenario, cycle, or None.
• version: The string indicates the application version of the sequence to instantiate. If not provided, the current version is used. For more details, refer to version management.
• Each property of the properties dictionary is also directly exposed as an attribute.
• Each nested entity is also exposed as an attribute of the sequence. The attribute name corresponds to the config_id of the nested entity.

Example

import taipy as tp
from datetime import datetime
import my_config

scenario = tp.create_scenario(my_config.monthly_scenario_cfg, name="Monthly scenario")
sales_sequence = scenario.sales_sequence
sales_sequence.name = "Sequence for sales prediction"

# There was no subscription, so subscribers is an empty list
sequence.subscribers # []
# The properties dictionary equals {"name": "Sequence for sales prediction"}. It
# contains all the properties, including the `name` provided at the creation
sequence.properties # {"name": "Sequence for sales prediction"}
# The `name` property is also exposed directly as an attribute. It
# equals "Sequence for sales prediction"
sequence.name
# The training task entity is exposed as an attribute of the sequence
training_task = sequence.training
# The predicting task entity as well
predicting_task = sequence.predicting
# The data nodes are also exposed as attributes of the sequence.
current_month_data_node = sequence.current_month

Get a sequence

There are two ways to retrieve a sequence:

The first method is by getting it from its parent scenario, using the sequence name as an attribute. The second method to access a sequence is from its id using the taipy.get() method.

import taipy as tp
import my_config

scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
sequence = scenario.sales_sequence

sequence_retrieved = tp.get(sequence.id)
sequence == sequence_retrieved

Here the two variables sequence and sequence_retrieved are equal.

Get all sequences

All the sequences can be retrieved using the method taipy.get_sequences(). This method returns the list of all existing sequences.

Delete a sequence

A sequence can be deleted by using taipy.delete() which takes the sequence id as a parameter. The deletion is also propagated to the nested tasks, data nodes, and jobs if they are not shared with any other sequence.

Get parent scenarios

To get the parent entities of a sequence (i.e., scenarios) you can use either the method DataNode.get_parents() or the function taipy.get_parents(). Both return the parents of the sequence.

Example

import taipy as tp
import my_config

# Create a scenario from a config
scenario = tp.create_scenario(my_config.monthly_scenario_cfg)

# Retrieve a sequence
sequence = scenario.sales_sequence_cfg

# Retrieve the parent entities of the sequence
parent_entities = sequence.get_parents()  # {'scenarios': [Scenario 1]}

# Retrieve the parent entities of the sequence
tp.get_parents(sequence)  # {'scenarios': [Scenario 1]}

The next sections show the task management.