Python param.Parameter() Examples

def process_dynamic_args(x, y, kind, **kwds):
    dynamic = {}
    arg_deps = []
    arg_names = []

    for k, v in list(kwds.items()) + [('x', x), ('y', y), ('kind', kind)]:
        if isinstance(v, param.Parameter):
            dynamic[k] = v
        elif panel_available and isinstance(v, pn.widgets.Widget):
            if LooseVersion(pn.__version__) < '0.6.4':
                dynamic[k] = v.param.value
            else:
                dynamic[k] = v

    for k, v in kwds.items():
        if k not in dynamic and isinstance(v, FunctionType) and hasattr(v, '_dinfo'):
            deps = v._dinfo['dependencies']
            arg_deps += list(deps)
            arg_names += list(k) * len(deps)

    return dynamic, arg_deps, arg_names 

def test_param_rename():
    "Test that Reactive renames params and properties"

    class ReactiveRename(Reactive):

        a = param.Parameter()
    
        _rename = {'a': 'b'}

    obj = ReactiveRename()

    params = obj._process_property_change({'b': 1})
    assert params == {'a': 1}

    properties = obj._process_param_change({'a': 1})
    assert properties == {'b': 1} 

def test_param_subobject_expand_no_toggle(document, comm):
    class Test(param.Parameterized):
        a = param.Parameter()

    test = Test(a=Test(name='Nested'))
    test_pane = Pane(test, expand=True,
                     expand_button=False)
    model = test_pane.get_root(document, comm=comm)

    # Assert no toggle was added
    assert len(model.children) == 3

    # Expand subpane
    _, _, subpanel = test_pane.layout.objects
    div, widget = model.children[2].children
    assert div.text == '<b>Nested</b>'
    assert isinstance(widget, BkTextInput) 

def _validate_object(self):
        dependencies = getattr(self.object, '_dinfo', None)
        if not dependencies or not dependencies.get('watch'):
            return
        fn_type = 'method' if type(self) is ParamMethod else 'function'
        self.param.warning(f"The {fn_type} supplied for Panel to display "
                           "was declared with `watch=True`, which will "
                           f"cause the {fn_type} to be called twice for "
                           "any change in a dependent Parameter. "
                           "`watch` should be False when Panel is "
                           "responsible for displaying the result "
                           f"of the {fn_type} call, while `watch=True` "
                           f"should be reserved for {fn_type}s that work "
                           "via side-effects, e.g. by modifying internal  "
                           "state of a class or global state in an "
                           "application's namespace.")

    #----------------------------------------------------------------
    # Callback API
    #---------------------------------------------------------------- 

def __call__(self, element, **kwargs):
        params = dict(kwargs)
        for k, v in kwargs.items():
            if util.is_param_method(v, has_deps=True):
                params[k] = v()
            elif isinstance(v, param.Parameter) and isinstance(v.owner, param.Parameterized):
                params[k] = getattr(v.owner, v.name)
        self.p = param.ParamOverrides(self, params,
                                      allow_extra_keywords=self._allow_extra_keywords)
        if not self.p.dynamic:
            kwargs['dynamic'] = False
            if isinstance(element, HoloMap):
                # Backwards compatibility for key argument
                return element.clone([(k, self._apply(el, key=k))
                                      for k, el in element.items()])
            elif ((self._per_element and isinstance(element, Element)) or
                  (not self._per_element and isinstance(element, ViewableElement))):
                return self._apply(element)
        elif 'streams' not in kwargs:
            kwargs['streams'] = self.p.streams
        kwargs['per_element'] = self._per_element
        kwargs['link_dataset'] = self._propagate_dataset
        return element.apply(self, **kwargs) 

def param_value_if_widget(arg):
    if isinstance(arg, Widget):
        return arg.param.value

    from .pane.ipywidget import IPyWidget
    if IPyWidget.applies(arg) and hasattr(arg, 'value'):
        name = type(arg).__name__
        if name in ipywidget_classes:
            ipy_param = ipywidget_classes[name]
        else:
            ipy_param = param.parameterized_class(name, {'value': param.Parameter()})
        ipywidget_classes[name] = ipy_param
        ipy_inst = ipy_param(value=arg.value)
        arg.observe(lambda event: ipy_inst.set_param(value=event['new']), 'value')
        return ipy_inst.param.value
    return arg 

def _yield_abbreviations_for_parameter(parameter, kwargs):
    """Get an abbreviation for a function parameter."""
    name = parameter.name
    kind = parameter.kind
    ann = parameter.annotation
    default = parameter.default
    not_found = (name, empty, empty)
    if kind in (Parameter.POSITIONAL_OR_KEYWORD, Parameter.KEYWORD_ONLY):
        if name in kwargs:
            value = kwargs.pop(name)
        elif ann is not empty:
            param.main.warning("Using function annotations to implicitly specify interactive controls is deprecated. "
                               "Use an explicit keyword argument for the parameter instead.", DeprecationWarning)
            value = ann
        elif default is not empty:
            value = default
            if isinstance(value, (Iterable, Mapping)):
                value = fixed(value)
        else:
            yield not_found
        yield (name, value, default)
    elif kind == Parameter.VAR_KEYWORD:
        # In this case name=kwargs and we yield the items in kwargs with their keys.
        for k, v in kwargs.copy().items():
            kwargs.pop(k)
            yield k, v, empty 

def test_link():
    "Link two Reactive objects"

    class ReactiveLink(Reactive):

        a = param.Parameter()

    obj = ReactiveLink()
    obj2 = ReactiveLink()
    obj.link(obj2, a='a')
    obj.a = 1

    assert obj.a == 1
    assert obj2.a == 1 

def test_expand_param_subobject_tabs(document, comm):
    class Test(param.Parameterized):
        abc = param.Parameter()

    test = Test(abc=Test(name='Nested'), name='A')
    test_pane = Pane(test, expand_layout=Tabs)
    model = test_pane.get_root(document, comm=comm)

    toggle = model.tabs[0].child.children[0].children[1]
    assert isinstance(toggle, Toggle)

    # Expand subpanel
    test_pane._widgets['abc'][1].value = True
    assert len(model.tabs) == 2
    _, subpanel = test_pane.layout.objects
    subtabs = model.tabs[1].child
    assert model.tabs[1].title == 'Abc'
    assert isinstance(subtabs, BkTabs)
    assert len(subtabs.tabs) == 1
    assert subtabs.tabs[0].title == 'Nested'

    box = subtabs.tabs[0].child
    assert isinstance(box, BkColumn)
    assert len(box.children) == 1
    widget = box.children[0]
    assert isinstance(widget, BkTextInput)

    # Collapse subpanel
    test_pane._widgets['abc'][1].value = False
    assert len(model.tabs) == 1 

def test_expand_param_subobject_into_row(document, comm):
    class Test(param.Parameterized):
        a = param.Parameter()

    test = Test(a=Test(name='Nested'))
    row = Row()
    test_pane = Pane(test, expand_layout=row)
    layout = Row(test_pane, row)
    model = layout.get_root(document, comm=comm)

    toggle = model.children[0].children[1].children[1]
    assert isinstance(toggle, Toggle)

    # Expand subpane
    test_pane._widgets['a'][1].value = True
    assert len(model.children) == 2
    subpanel = row.objects[0]
    row = model.children[1]
    assert isinstance(row, BkRow)
    assert len(row.children) == 1
    box = row.children[0]
    assert isinstance(box, BkColumn)
    assert len(box.children) == 2
    div, widget = box.children
    assert div.text == '<b>Nested</b>'
    assert isinstance(widget, BkTextInput)

    # Collapse subpanel
    test_pane._widgets['a'][1].value = False
    assert len(row.children) == 0
    assert subpanel._models == {} 

def test_expand_param_subobject(document, comm):
    class Test(param.Parameterized):
        a = param.Parameter()

    test = Test(a=Test(name='Nested'))
    test_pane = Pane(test)
    model = test_pane.get_root(document, comm=comm)

    toggle = model.children[1].children[1]
    assert isinstance(toggle, Toggle)

    # Expand subpane
    test_pane._widgets['a'][1].value = True
    assert len(model.children) == 3
    _, _, subpanel = test_pane.layout.objects
    col = model.children[2]
    assert isinstance(col, BkColumn)
    assert isinstance(col, BkColumn)
    assert len(col.children) == 2
    div, widget = col.children
    assert div.text == '<b>Nested</b>'
    assert isinstance(widget, BkTextInput)

    # Collapse subpanel
    test_pane._widgets['a'][1].value = False
    assert len(model.children) == 2 

def test_single_param(document, comm):

    class Test(param.Parameterized):
        a = param.Parameter(default=0)

    test = Test()
    test_pane = Pane(test.param.a)
    model = test_pane.get_root(document, comm=comm)

    assert isinstance(model, BkColumn)
    assert len(model.children) == 1

    widget = model.children[0]
    assert isinstance(widget, TextInput)
    assert widget.value == '0' 

def test_widget_from_param_instance():
    class Test(param.Parameterized):

        a = param.Parameter()

    test = Test()
    widget = TextInput.from_param(test.param.a)
    assert isinstance(widget, TextInput)
    assert widget.name == 'A'

    test.a = 'abc'
    assert widget.value == 'abc'

    widget.value = 'def'
    assert test.a == 'def' 

def test_widget_from_param_cls():
    class Test(param.Parameterized):

        a = param.Parameter()

    widget = TextInput.from_param(Test.param.a)
    assert isinstance(widget, TextInput)
    assert widget.name == 'A'

    Test.a = 'abc'
    assert widget.value == 'abc'

    widget.value = 'def'
    assert Test.a == 'def' 

def eval(self, function):
        args, kwargs = (), {}
        if hasattr(function, '_dinfo'):
            arg_deps = function._dinfo['dependencies']
            kw_deps = function._dinfo.get('kw', {})
            if kw_deps or any(isinstance(d, param.Parameter) for d in arg_deps):
                args = (getattr(dep.owner, dep.name) for dep in arg_deps)
                kwargs = {n: getattr(dep.owner, dep.name) for n, dep in kw_deps.items()}
        return function(*args, **kwargs) 

def applies(cls, obj):
        return (is_parameterized(obj) or
                isinstance(obj, param.parameterized.Parameters) or
                (isinstance(obj, param.Parameter) and obj.owner is not None)) 

def __init__(self, object=None, **params):
        if isinstance(object, param.Parameter):
            if not 'show_name' in params:
                params['show_name'] = False
            params['parameters'] = [object.name]
            object = object.owner
        if isinstance(object, param.parameterized.Parameters):
            object = object.cls if object.self is None else object.self
        if 'parameters' not in params and object is not None:
            params['parameters'] = [p for p in object.param if p != 'name']
        if object and 'name' not in params:
            params['name'] = param_name(object.name)
        super(Param, self).__init__(object, **params)
        self._updating = []

        # Construct Layout
        kwargs = {p: v for p, v in self.param.get_param_values()
                  if p in Layoutable.param and v is not None}
        self._widget_box = self.default_layout(**kwargs)

        layout = self.expand_layout
        if isinstance(layout, Panel):
            self._expand_layout = layout
            self.layout = self._widget_box
        elif isinstance(self._widget_box, layout):
            self.layout = self._expand_layout = self._widget_box
        elif isinstance(layout, type) and issubclass(layout, Panel):
            self.layout = self._expand_layout = layout(self._widget_box, **kwargs)
        else:
            raise ValueError('expand_layout expected to be a panel.layout.Panel'
                             'type or instance, found %s type.' %
                             type(layout).__name__)
        self.param.watch(self._update_widgets, [
            'object', 'parameters', 'name', 'display_threshold', 'expand_button',
            'expand', 'expand_layout', 'widgets', 'show_labels', 'show_name'])
        self._update_widgets() 

def __set__(self, obj, val):
        """
        Set a non default bounding box, use the installed set hook to
        apply any conversion or transformation on the coordinates and
        create a new bounding box with the converted coordinate set.
        """
        coords = [self.set_hook(obj, point) for point in val.lbrt()]
        if coords != val.lbrt():
            val = BoundingBox(
                points=[(coords[0], coords[1]), (coords[2], coords[3])])

        if not isinstance(val, BoundingRegion):
            raise ValueError("Parameter must be a BoundingRegion.")
        else:
            super(BoundingRegionParameter, self).__set__(obj, val) 

def resolve_dependent_value(value):
    """Resolves parameter dependencies on the supplied value

    Resolves parameter values, Parameterized instance methods and
    parameterized functions with dependencies on the supplied value.

    Args:
       value: A value which will be resolved

    Returns:
       A new dictionary where any parameter dependencies have been
       resolved.
    """
    if 'panel' in sys.modules:
        from panel.widgets.base import Widget
        if isinstance(value, Widget):
            value = value.param.value
    if is_param_method(value, has_deps=True):
        value = value()
    elif isinstance(value, param.Parameter) and isinstance(value.owner, param.Parameterized):
        value = getattr(value.owner, value.name)
    elif isinstance(value, FunctionType) and hasattr(value, '_dinfo'):
        deps = value._dinfo
        args = (getattr(p.owner, p.name) for p in deps.get('dependencies', []))
        kwargs = {k: getattr(p.owner, p.name) for k, p in deps.get('kw', {}).items()}
        value = value(*args, **kwargs)
    return value 

def _update_backend(cls, backend):

        if cls.__original_docstring__ is None:
            cls.__original_docstring__ = cls.__doc__

        all_keywords = set()
        element_keywords = cls._element_keywords(backend)
        for element, keywords in element_keywords.items():
            with param.logging_level('CRITICAL'):
                all_keywords |= set(keywords)
                setattr(cls, element,
                        cls._create_builder(element, keywords))

        filtered_keywords = [k for k in all_keywords if k not in cls._no_completion]
        sorted_kw_set = sorted(set(filtered_keywords))
        if sys.version_info.major == 2:
            kws = ', '.join('{opt}=None'.format(opt=opt) for opt in sorted_kw_set)
            old_doc = cls.__original_docstring__.replace(
                'params(strict=Boolean, name=String)','')
            cls.__doc__ = '\n    opts({kws})'.format(kws=kws) + old_doc
        else:
            from inspect import Parameter, Signature
            signature = Signature([Parameter('args', Parameter.VAR_POSITIONAL)]
                                  + [Parameter(kw, Parameter.KEYWORD_ONLY)
                                     for kw in sorted_kw_set])
            cls.__init__.__signature__ = signature 

def params(self):
        params = {}
        for op in self.ops:
            op_args = list(op['args'])+list(op['kwargs'].values())
            for op_arg in op_args:
                if 'panel' in sys.modules:
                    from panel.widgets.base import Widget
                    if isinstance(op_arg, Widget):
                        op_arg = op_arg.param.value
                if (isinstance(op_arg, param.Parameter) and
                    isinstance(op_arg.owner, param.Parameterized)):
                    params[op_arg.name+str(id(op))] = op_arg
        return params

    # Namespace properties 

def test_XY_set_invalid_instance_y(self):
        xy = self.XY(x=1,y=2)
        regexp = "Parameter 'y' only takes numeric values"
        with self.assertRaisesRegexp(ValueError, regexp):
            xy.y = 'string' 

def test_XY_set_invalid_instance_x(self):
        xy = self.XY(x=1,y=2)
        regexp = "Parameter 'x' only takes numeric values"
        with self.assertRaisesRegexp(ValueError, regexp):
            xy.x = 'string' 

def test_XY_set_invalid_class_y(self):
        regexp = "Parameter 'y' only takes numeric values"
        with self.assertRaisesRegexp(ValueError, regexp):
            self.XY.y = 'string' 

def test_all_stream_parameters_constant():
    all_stream_cls = [v for v in globals().values() if
                      isinstance(v, type) and issubclass(v, Stream)]
    for stream_cls in all_stream_cls:
        for name, p in stream_cls.param.params().items():
            if name == 'name': continue
            if p.constant != True:
                raise TypeError('Parameter %s of stream %s not declared constant'
                                % (name, stream_cls.__name__)) 

def __init__(self, parameterized=None, parameters=None, watch=True, watch_only=False, **params):
        if util.param_version < '1.8.0' and watch:
            raise RuntimeError('Params stream requires param version >= 1.8.0, '
                               'to support watching parameters.')
        if parameters is None:
            parameters = [parameterized.param[p] for p in parameterized.param if p != 'name']
        else:
            parameters = [p if isinstance(p, param.Parameter) else parameterized.param[p]
                          for p in parameters]

        if 'rename' in params:
            rename = {}
            owners = [p.owner for p in parameters]
            for k, v in params['rename'].items():
                if isinstance(k, tuple):
                    rename[k] = v
                else:
                    rename.update({(o, k): v for o in owners})
            params['rename'] = rename

        self._watch_only = watch_only
        super(Params, self).__init__(parameterized=parameterized, parameters=parameters, **params)
        self._memoize_counter = 0
        self._events = []
        self._watchers = []
        if watch:
            # Subscribe to parameters
            keyfn = lambda x: id(x.owner)
            for _, group in groupby(sorted(parameters, key=keyfn)):
                group = list(group)
                watcher = group[0].owner.param.watch(self._watcher, [p.name for p in group])
                self._watchers.append(watcher) 

def define(cls, name, **kwargs):
        """
        Utility to quickly and easily declare Stream classes. Designed
        for interactive use such as notebooks and shouldn't replace
        parameterized class definitions in source code that is imported.

        Takes a stream class name and a set of keywords where each
        keyword becomes a parameter. If the value is already a
        parameter, it is simply used otherwise the appropriate parameter
        type is inferred and declared, using the value as the default.

        Supported types: bool, int, float, str, dict, tuple and list
        """
        params = {'name': param.String(default=name)}
        for k, v in kwargs.items():
            kws = dict(default=v, constant=True)
            if isinstance(v, param.Parameter):
                params[k] = v
            elif isinstance(v, bool):
                params[k] = param.Boolean(**kws)
            elif isinstance(v, int):
                params[k] = param.Integer(**kws)
            elif isinstance(v, float):
                params[k] = param.Number(**kws)
            elif isinstance(v, str):
                params[k] = param.String(**kws)
            elif isinstance(v, dict):
                params[k] = param.Dict(**kws)
            elif isinstance(v, tuple):
                params[k] = param.Tuple(**kws)
            elif isinstance(v, list):
                params[k] = param.List(**kws)
            elif isinstance(v, np.ndarray):
                params[k] = param.Array(**kws)
            else:
                params[k] = param.Parameter(**kws)

        # Dynamic class creation using type
        return type(name, (Stream,), params) 

def setUp(self):
        if LooseVersion(param.__version__) < '1.8.0':
            raise SkipTest('Params stream requires param >= 1.8.0')

        class Inner(param.Parameterized):

            action = param.Action(lambda o: o.param.trigger('action'))
            x = param.Number(default = 0)
            y = param.Number(default = 0)
            count = param.Integer(default=0)

            @param.depends('x')
            def method(self):
                self.count += 1
                return Points([])

            @param.depends('action')
            def action_method(self):
                pass

            @param.depends('action', 'x')
            def action_number_method(self):
                self.count += 1
                return Points([])

            @param.depends('y')
            def op_method(self, obj):
                pass

            def method_no_deps(self):
                pass

        class InnerSubObj(Inner):

            sub = param.Parameter()

            @param.depends('sub.x')
            def subobj_method(self):
                pass

        self.inner = Inner
        self.innersubobj = InnerSubObj 

def _process_streams(cls, streams):
        """
        Processes a list of streams promoting Parameterized objects and
        methods to Param based streams.
        """
        parameterizeds = defaultdict(set)
        valid, invalid = [], []
        for s in streams:
            if isinstance(s, partial):
                s = s.func
            if isinstance(s, Stream):
                pass
            elif isinstance(s, param.Parameter):
                s = Params(s.owner, [s.name])
            elif isinstance(s, param.Parameterized):
                s = Params(s)
            elif util.is_param_method(s):
                if not hasattr(s, "_dinfo"):
                    continue
                s = ParamMethod(s)
            elif isinstance(s, FunctionType) and hasattr(s, "_dinfo"):
                deps = s._dinfo
                dep_params = list(deps['dependencies']) + list(deps.get('kw', {}).values())
                rename = {(p.owner, p.name): k for k, p in deps.get('kw', {}).items()}
                s = Params(parameters=dep_params, rename=rename)
            else:
                invalid.append(s)
                continue
            if isinstance(s, Params):
                pid = id(s.parameterized)
                overlap = (set(s.parameters) & parameterizeds[pid])
                if overlap:
                    pname = type(s.parameterized).__name__
                    param.main.param.warning(
                        'The %s parameter(s) on the %s object have '
                        'already been supplied in another stream. '
                        'Ensure that the supplied streams only specify '
                        'each parameter once, otherwise multiple '
                        'events will be triggered when the parameter '
                        'changes.' % (sorted([p.name for p in overlap]), pname))
                parameterizeds[pid] |= set(s.parameters)
            valid.append(s)
        return valid, invalid 

def trigger(cls, streams):
        """
        Given a list of streams, collect all the stream parameters into
        a dictionary and pass it to the union set of subscribers.

        Passing multiple streams at once to trigger can be useful when a
        subscriber may be set multiple times across streams but only
        needs to be called once.
        """
        # Union of stream contents
        items = [stream.contents.items() for stream in set(streams)]
        union = [kv for kvs in items for kv in kvs]
        klist = [k for k, _ in union]
        key_clashes = []
        for k, v in union:
            key_count = klist.count(k)
            try:
                value_count = union.count((k, v))
            except Exception:
                # If we can't compare values we assume they are not equal
                value_count = 1
            if key_count > 1 and key_count > value_count and k not in key_clashes:
                key_clashes.append(k)
        if key_clashes:
            print('Parameter name clashes for keys %r' % key_clashes)

        # Group subscribers by precedence while keeping the ordering
        # within each group
        subscriber_precedence = defaultdict(list)
        for stream in streams:
            stream._on_trigger()
            for precedence, subscriber in stream._subscribers:
                subscriber_precedence[precedence].append(subscriber)
        sorted_subscribers = sorted(subscriber_precedence.items(), key=lambda x: x[0])
        subscribers = util.unique_iterator([s for _, subscribers in sorted_subscribers
                                            for s in subscribers])

        with triggering_streams(streams):
            for subscriber in subscribers:
                subscriber(**dict(union))

        for stream in streams:
            with util.disable_constant(stream):
                if stream.transient:
                    stream.reset()