The data types that are available in Sympathy include Table, ADAF, Text, and lists of these types, but if the need should arise you can also make your own data type.
Please keep in mind that this is an advanced operation that is not needed for most users. Furthermore:
Nodes can only be connected to other nodes that use the same data type. So a node using your own data type can only be connected to other nodes that use your own data type.
Do not duplicate functionality for several different data types. For example Select rows operation should probably only exist for Table.
Create paths to and from Table or some other native data type so people using your nodes can still benefit from the standard library and any third party libraries using the standard data types. See Working with ADAF for an example.
By following this guide, you should be able to create a new composite data type out of the existing fundamental data types in sympathy. An example of such a data type is the ADAF. Even many types of data which are not most naturally represented as a hierarchical collection of tables can be created in this fashion. For example an array type could be created by using a single table and building a specialized and more restrictive typeutil interface. Even the ubiquitous Table can be said to be a composite data type as it is a wrapper around the more fundamental sytable type.
Create typeutils class¶
This is a basic example of how to create an alias name for an existing type which does not introduce additional instance fields. TypeAlias classes introducing additional fields will have to re-implement more methods, these are outside the scope of this chapter. See Data types for reference material.
Creating a new type, requires subclassing
sympathy.api.typeutil.TypeAlias and wrapping the class in the
The TypeAlias class has the following API (simplified version):
- class sympathy.api.typeutil.TypeAlias(filename: str | None = None, mode: str = 'r', **kwargs)
Base for implementing custom sympathy types. Data serialization is performed through self._data which is setup by __init__ and contains the storage level representation of the data.
If the object introduces additional instance fields, __deepcopy__ and sync likely have to be re-implemented. Carefully, read the relevant docstrings.
Do not implement __init__, instead implement init.
- names(kind=None, fields=None, **kwargs)
Return data related to names of some kind. In fact, names can go beyond finding names and find for example types.
Useful if this type has some kind of names that would be useful in adjust_parameters.
kind (str) – The kind of names your are interested in.
fields (str or [str]) – The fields you would like to include in the result. For example, name and type.
Normally, containing scalar elements if fields is scalar and tuple of multiple such elements when fields is list.
- Return type:
list or iterator
This is the only mandatory step towards creating your own data type. Create a
new Python file anywhere in the package folder of your library. To locate the
package folder first find out which library format that you are using:
New Library Format or Old Library Format and then locate <package-name> in that
Library structure. Name the python file as your data type, all lower case. In
our example the <package-name> is boblib and we will place the file at
boblib/twin_tables.py. Open your new file and add a TypeAlias subclass called
TwinTables wrapped in the typeutil decorator. Use the method
init to do
import os from sympathy.api import typeutil # Full path to the directory where this file is located. _directory = os.path.abspath(os.path.dirname(__file__)) @typeutil.typeutil('sytypealias twin_tables = (first: table, second: table)') class TwinTables(typeutil.TypeAlias): """Twin tables.""" @property def first(self): return self._data.first @property def second(self): return self._data.second @classmethod def viewer(cls): from . import twin_tables_viewer return twin_tables_viewer.TwinTablesViewer @classmethod def icon(cls): return os.path.join(_directory, 'port_twin_tables.svg')
The argument to the decorator is the declaration of your data type. It can
contain a combination of basic data types (such as
other composite types (such as
table), and container types
Create a list of elements by surrounding the name of a type in brackets. For example
Create a dictionary of elements by surrounding the name of a type in curly braces. For example
A record contains a few fixed elements. Create a record by surrounding key-value pairs with parenthesis. For example
(projects: sytable, coffee_budget: sytable). The values must all be valid types and the keys must all be valid python identifiers. As seen in the example above the elements are available as attributes of the record.
The instance variable
self._data will contain the declared data structure.
Where applicable, stuff in
self._data will be wrapped in the correct
typeutil class. In the above example the tables will be wrapped in the
sympathy.api.table.Table, but if the declared type had
'(first: sytable, second: sytable)', the tables would be bare
types.sytable objects and not wrapped in the typeutils class.
The typeutil class should contain any interface to the data that you want to
expose to nodes working with this data type. In our example the interface is
simply two instance variables called
second, but for example
the typeutils class for the table type defines many methods for reading and
writing data and the ADAF typeutil even defines several additional classes.
Locate port type¶
In order for the type to be fully usable, Sympathy needs to be able to locate it. It is located using a function called library_types() that should be present in the __init__.py file of your package.
Example from the standard library:
# Filename sylib/__init__.py import sympathy.api def library_types(): return [ sympathy.api.adaf.ADAF, sympathy.api.datasource.Datasource, sympathy.api.figure.Figure, sympathy.api.report.File, sympathy.api.table.Table, sympathy.api.text.Text, ]
For TwinTables it would look something like:
# Filename boblib/__init__.py from . import twin_tables def library_types(): return [twin_tables.TwinTables]
Create port type¶
This step is not strictly necessary but will make it easier to create nodes
that use your data type. Add a new port type function to the same file as your
typeutils class. It should be similar to the static methods of the
from sympathy.utils import port def TwinTables(description, name=None): return port.CustomPort('twin_tables', description, name=name)
Create an example node¶
Create a node that uses the new port type:
import numpy as np from sympathy.api import node as synode from sympathy.api.nodeconfig import Ports from boblib.twin_tables import TwinTables class TwinTablesExample(synode.Node): """ Outputs a twin table with one column in the first table with values 1-99. """ name = 'Twin tables example' description = 'Outputs a twin table with one column in first table with values 1-99.' icon = 'example.svg' nodeid = 'org.sysess.sympathy.examples.twintablesexample' author = 'Magnus Sanden <firstname.lastname@example.org>' copyright = '(c) 2014 Combine Control Systems AB' version = '1.0' outputs = Ports([TwinTables('Output', name='port1')]) def execute(self, node_context): """Execute node""" tablefile = node_context.output['port1'].first data = np.arange(1, 101, dtype=int) tablefile.set_name('Output Example') tablefile.set_column_from_array('Enumeration', data)
Look at the data on the out port by right-clicking on it and choosing Copy File Path To Clipboard and pasting the path into HDF5View.
Adding an icon¶
To customize your new type by adding an icon, first create an svg icon for TwinTables. See the icons in Sympathy/Gui/Resources/icons/ports for more details about what the platform icons look like.
Icons should have a width and height of 16. Use an existing platform icon as a template if you are uncertain. If this criteria is not met, the icon will be scaled and cropped to a width and height of 16 automatically.
Once the icon is created, copy it to boblib/port_twin_tables.svg. The free software Inkscape can be used to create the icons.
Extend the data viewer¶
To be able to view the data on ports of type twin_tables, a new viewer needs to be created.
Add a module called twin_tables_viewer.py to boblib/twin_tables_viewer.py with the following code:
from sympathy.api import table from sympathy.api import qt2 from sympathy.api.typeutil import ViewerBase class TwinTablesViewer(ViewerBase): def __init__(self, data=None, console=None, parent=None): super().__init__(parent) TableViewer = table.Table.viewer() self._table1_viewer = TableViewer() self._table2_viewer = TableViewer() layout = qt2.QtWidgets.QVBoxLayout() layout.addWidget(self._table1_viewer) layout.addWidget(self._table2_viewer) self.setLayout(layout) self.update_data(data) def data(self): return self._data def update_data(self, data): self._data = data if data is not None: self._table1_viewer.update_data(data.first) self._table2_viewer.update_data(data.second)