PlotScalar¶

class metpy.plots.PlotScalar(**kwargs)[source]¶

Defines the common elements of 2D scalar plots for single scalar value fields.

Most of the other traits here are for one or more of the specific plots. Currently this allows too many options for ContourPlot since it does not user image_range, for example. Similar issues for ImagePlot and FilledContourPlot.

Attributes Summary

`cross_validation_lock`	A contextmanager for running a block with our cross validation lock set to True.
`data`	Xarray dataset that contains the field to be plotted.
`field`	Name of the field to be plotted.
`griddata`	Return the internal cached data.
`level`	The level of the field to be plotted.
`name`	Generate a name for the plot.
`parent`	A trait whose value must be an instance of a specified class.
`plot_units`	The desired units to plot the field in.
`plotdata`	Return the data for plotting.
`scale`	Scale the field to be plotted by the value given.
`time`	Set the valid time to be plotted as a datetime object.

Methods Summary

`__init__`(args, *kwargs)	Initialize self.
`add_traits`(**traits)	Dynamically add trait attributes to the HasTraits instance.
`class_own_trait_events`(name)	Get a dict of all event handlers defined on this class, not a parent.
`class_own_traits`(**metadata)	Get a dict of all the traitlets defined on this class, not a parent.
`class_trait_names`(**metadata)	Get a list of all the names of this class’ traits.
`class_traits`(**metadata)	Get a `dict` of all the traits of this class.
`clear`()	Clear the plot.
`clear_collections`()	Clear the handle collections to the plot instance.
`clear_handle`()	Clear the handle to the plot instance.
`draw`()	Draw the plot.
`has_trait`(name)	Returns True if the object has a trait with the specified name.
`hold_trait_notifications`()	Context manager for bundling trait change notifications and cross validation.
`notify_change`(change)	Notify observers of a change event
`observe`(handler[, names, type])	Setup a handler to be called when a trait changes.
`on_trait_change`([handler, name, remove])	DEPRECATED: Setup a handler to be called when a trait changes.
`set_trait`(name, value)	Forcibly sets trait attribute, including read-only attributes.
`setup_instance`(**kwargs)	This is called before self.__init__ is called.
`trait_defaults`(names, *metadata)	Return a trait’s default value or a dictionary of them
`trait_events`([name])	Get a `dict` of all the event handlers of this class.
`trait_has_value`(name)	Returns True if the specified trait has a value.
`trait_metadata`(traitname, key[, default])	Get metadata values for trait by key.
`trait_names`(**metadata)	Get a list of all the names of this class’ traits.
`trait_values`(**metadata)	A `dict` of trait names and their values.
`traits`(**metadata)	Get a `dict` of all the traits of this class.
`unobserve`(handler[, names, type])	Remove a trait change handler.
`unobserve_all`([name])	Remove trait change handlers of any type for the specified name.

Attributes Documentation

cross_validation_lock¶

A contextmanager for running a block with our cross validation lock set to True.

At the end of the block, the lock’s value is restored to its value prior to entering the block.

data¶: Xarray dataset that contains the field to be plotted.

field¶

Name of the field to be plotted.

This is the name of the variable from the dataset that is to be plotted. An example, from a model grid file that uses the THREDDS convention for naming would be Geopotential_height_isobaric or Temperature_isobaric. For GOES-16/17 satellite data it might be Sectorized_CMI. To check for the variables available within a dataset, list the variables with the following command assuming the dataset was read using xarray as ds, list(ds)

griddata¶: Return the internal cached data.

level¶

The level of the field to be plotted.

This is a value with units to choose the desired plot level. For example, selecting the 850-hPa level, set this parameter to 850 * units.hPa

name¶: Generate a name for the plot.

parent¶

A trait whose value must be an instance of a specified class.

The value can also be an instance of a subclass of the specified class.

Subclasses can declare default classes by overriding the klass attribute

plot_units¶

The desired units to plot the field in.

Setting this attribute will convert the units of the field variable to the given units for plotting using the MetPy Units module.

plotdata¶

Return the data for plotting.

The data array, x coordinates, and y coordinates.

scale¶

Scale the field to be plotted by the value given.

This attribute will scale the field by multiplying by the scale. For example, to scale vorticity to be whole values for contouring you could set the scale to 1e5, such that the data values will be scaled by 10^5.

time¶

Set the valid time to be plotted as a datetime object.

If a forecast hour is to be plotted the time should be set to the valid future time, which can be done using the datetime and timedelta objects from the Python standard library.

Methods Documentation

__init__(*args, **kwargs)¶: Initialize self. See help(type(self)) for accurate signature.

add_traits(**traits)¶: Dynamically add trait attributes to the HasTraits instance.

classmethod class_own_trait_events(name)¶

Get a dict of all event handlers defined on this class, not a parent.

Works like event_handlers, except for excluding traits from parents.

classmethod class_own_traits(**metadata)¶

Get a dict of all the traitlets defined on this class, not a parent.

Works like class_traits, except for excluding traits from parents.

classmethod class_trait_names(**metadata)¶

Get a list of all the names of this class’ traits.

This method is just like the trait_names() method, but is unbound.

classmethod class_traits(**metadata)¶

Get a dict of all the traits of this class. The dictionary is keyed on the name and the values are the TraitType objects.

This method is just like the traits() method, but is unbound.

The TraitTypes returned don’t know anything about the values that the various HasTrait’s instances are holding.

The metadata kwargs allow functions to be passed in which filter traits based on metadata values. The functions should take a single value as an argument and return a boolean. If any function returns False, then the trait is not included in the output. If a metadata key doesn’t exist, None will be passed to the function.

clear()¶

Clear the plot.

Resets all internal state and sets need for redraw.

clear_collections()¶: Clear the handle collections to the plot instance.

clear_handle()¶: Clear the handle to the plot instance.

draw()[source]¶: Draw the plot.

has_trait(name)¶: Returns True if the object has a trait with the specified name.

hold_trait_notifications()¶

Context manager for bundling trait change notifications and cross validation.

Use this when doing multiple trait assignments (init, config), to avoid race conditions in trait notifiers requesting other trait values. All trait notifications will fire after all values have been assigned.

notify_change(change)¶: Notify observers of a change event

observe(handler, names=traitlets.All, type='change')¶

Setup a handler to be called when a trait changes.

This is used to setup dynamic notifications of trait changes.

Parameters

handler (callable) – A callable that is called when a trait changes. Its signature should be handler(change), where change is a dictionary. The change dictionary at least holds a ‘type’ key. * type: the type of notification. Other keys may be passed depending on the value of ‘type’. In the case where type is ‘change’, we also have the following keys: * owner : the HasTraits instance * old : the old value of the modified trait attribute * new : the new value of the modified trait attribute * name : the name of the modified trait attribute.
names (list, str, All) – If names is All, the handler will apply to all traits. If a list of str, handler will apply to all names in the list. If a str, the handler will apply just to that name.
type (str, All (default: 'change')) – The type of notification to filter by. If equal to All, then all notifications are passed to the observe handler.

on_trait_change(handler=None, name=None, remove=False)¶

DEPRECATED: Setup a handler to be called when a trait changes.

This is used to setup dynamic notifications of trait changes.

Static handlers can be created by creating methods on a HasTraits subclass with the naming convention ‘_[traitname]_changed’. Thus, to create static handler for the trait ‘a’, create the method _a_changed(self, name, old, new) (fewer arguments can be used, see below).

If remove is True and handler is not specified, all change handlers for the specified name are uninstalled.

Parameters

handler (callable, None) – A callable that is called when a trait changes. Its signature can be handler(), handler(name), handler(name, new), handler(name, old, new), or handler(name, old, new, self).
name (list, str, None) – If None, the handler will apply to all traits. If a list of str, handler will apply to all names in the list. If a str, the handler will apply just to that name.
remove (bool) – If False (the default), then install the handler. If True then unintall it.

set_trait(name, value)¶: Forcibly sets trait attribute, including read-only attributes.

setup_instance(**kwargs)¶: This is called before self.__init__ is called.

trait_defaults(*names, **metadata)¶

Return a trait’s default value or a dictionary of them

Notes

Dynamically generated default values may depend on the current state of the object.

classmethod trait_events(name=None)¶

Get a dict of all the event handlers of this class.

Parameters: name (str (default: None)) – The name of a trait of this class. If name is None then all the event handlers of this class will be returned instead.
Returns: The event handlers associated with a trait name, or all event handlers.

trait_has_value(name)¶

Returns True if the specified trait has a value.

This will return false even if getattr would return a dynamically generated default value. These default values will be recognized as existing only after they have been generated.

Example

class MyClass(HasTraits):
    i = Int()

mc = MyClass()
assert not mc.trait_has_value("i")
mc.i # generates a default value
assert mc.trait_has_value("i")

trait_metadata(traitname, key, default=None)¶: Get metadata values for trait by key.

trait_names(**metadata)¶: Get a list of all the names of this class’ traits.

trait_values(**metadata)¶

A dict of trait names and their values.

Returns: A dict of trait names and their values.

Notes

Trait values are retrieved via getattr, any exceptions raised by traits or the operations they may trigger will result in the absence of a trait value in the result dict.

traits(**metadata)¶

Get a dict of all the traits of this class. The dictionary is keyed on the name and the values are the TraitType objects.

The TraitTypes returned don’t know anything about the values that the various HasTrait’s instances are holding.

unobserve(handler, names=traitlets.All, type='change')¶

Remove a trait change handler.

This is used to unregister handlers to trait change notifications.

Parameters

handler (callable) – The callable called when a trait attribute changes.
names (list, str, All (default: All)) – The names of the traits for which the specified handler should be uninstalled. If names is All, the specified handler is uninstalled from the list of notifiers corresponding to all changes.
type (str or All (default: 'change')) – The type of notification to filter by. If All, the specified handler is uninstalled from the list of notifiers corresponding to all types.

unobserve_all(name=traitlets.All)¶: Remove trait change handlers of any type for the specified name. If name is not specified, removes all trait notifiers.

Examples using `metpy.plots.PlotScalar`¶

Simple Plotting¶

Combined Plotting¶

MetPy Declarative Syntax Tutorial¶

PlotObs PlotVector

PlotScalar¶

Examples using metpy.plots.PlotScalar¶

Examples using `metpy.plots.PlotScalar`¶