API¶

Variables¶

class xrviz.display.Display(data)¶

Displays a list of data variables for selection.

For each data, its variables are displayed in pn.widgets.MultiSelect. Variables which are data coordinates are annotated with ‘📈’.

Parameters

data: xarray.DataSet

Attributes

panel:: A panel.Row instance which displays the Multiselect widget.

Methods

select_variable(self, variable)

Select a data variable from the available options.

select_variable(self, variable)¶: Select a data variable from the available options.

class xrviz.describe.Describe(data)¶

Displays the properties of the variable selected in the Display section.

This section has two tables as output. The first table shows Variable attributes and the second table shows Global Attributes. Upon selection of a new variable in the Display widget, the first table updates itself with properties of the new selection, while the second table stays same.

Parameters

data: xarray.DataSet

Attributes

panel:: A panel.pane.HTML instance which displays the tables arranged next to each other.

Methods

variable_pane_for_dataset(self, var)

Returns HTML template describing variable and global attributes.

variable_pane_for_dataset(self, var)¶: Returns HTML template describing variable and global attributes.

Set_Coords¶

class xrviz.coord_setter.CoordSetter(data)¶

An input pane for choosing which variables are considered coordinates.

It uses a Cross Selector to display a list of simple and coordinate variables. Simple variables (which are not data coordinates) are available on left side and default coordinates are available on right side. To set variables as coordinates, make selection on left side and click >>. Similarly making selection on right side and clicking << will reset the coordinates. Other panes update themselves accordingly, in response to this change.

Methods

`set_coords`(self, data)	Called when the data attribute of the interface has change in variables considered as coordinates.
`setup_initial_values`(self[, init_params])	To set the variables, whose names have been passed, as coordinates.

set_coords(self, data)¶: Called when the data attribute of the interface has change in variables considered as coordinates.

setup_initial_values(self, init_params={})¶: To set the variables, whose names have been passed, as coordinates.

Axes¶

class xrviz.fields.Fields(data)¶

To select the fields to plot along.

This pane controls which array dimensions should be mapped, how additional dimensions should be handled, and which dimension series plots should be extracted along.

Parameters

data: xarray.DataSet

Attributes

x:

To select which of the available dimensions/coordinates in the data is assigned to the plot’s x (horizontal) axis.

y:

To select which of the available dimensions/coordinates in the data is assigned to the plot’s y (vertical) axis.

Remaining Dims:

Any one of the following aggregations can be applied on each of remaining dimensions:

select: It creates a pn.widgets.Select, to select the value of dimension, for which the graph would be displayed.

animate: It creates a panel.widgets.DiscretePlayer which helps to quickly iterate over all the values for a dimension.

mean: Creates plot along mean of the selected dimension.

max: Creates plot along maximum of the selected dimension.

min: Creates plot along minimum of the selected dimension.

median: Creates plot along median of the selected dimension.

std: Creates plot along standard deviation of the selected dimension.

count: Creates plot along non-nan values of the selected dimension.

Note that for both select and animate, the plot will update according to the value selected in the generated widget. Also, if a dimension has been aggregated, its select widget would not be available.

Extract Along:

This selector provides the option to select the dimension along which to create a series graph.

Methods

`change_dim_selectors`(self, \*args)	Updates the dimensions available for Aggregation and Extract Along upon change in value of `y`.
`change_y`(self[, value])	Updates `y` by removing the value of `x`, from the available options
`check_are_var_coords`(self)	Check if both `x` and `y` are coordinates of the selected variable.
`guess_x_y`(self, var)	To guess the value of `x` and `y` with metpy.parse_cf.
`setup`(self, var)	Fill available options for the selected variable.

change_dim_selectors(self, *args)¶: Updates the dimensions available for Aggregation and Extract Along upon change in value of y.

change_y(self, value=None)¶: Updates y by removing the value of x, from the available options

check_are_var_coords(self)¶: Check if both x and y are coordinates of the selected variable.

guess_x_y(self, var)¶: To guess the value of x and y with metpy.parse_cf. This is applicable only for the case when both x and y are data coordinates.

setup(self, var)¶: Fill available options for the selected variable.

Style¶

class xrviz.style.Style¶

A pane to customise styling of the graphs.

The following options are available in this pane:

height (default 300):
To modify the height of main and series graph.

width (default 700):
To modify the width of the main and series graph.

cmap (default Inferno):
To select a colormap for the main graph.

color_scale (default linear):
To scale the values to be plotted. The scaling options available are linear, exp, log, reciprocal, square and sqrt. Here linear implies no scaling.

cmap limits:
To change the colormap limits. User can fill these limits before plotting a variable. In case not filled by user, automatic filling of limits happen.

lower limit: auto-filled value equals quantile(0.1) of values to be plotted.

upper limit: auto-filled value equals quantile(0.9) of values to be plotted.

In case of dask array, dask.array.percentile is use to compute the limits. tdigest method is used in case crick is present. The value of limits is rounded off to 5 decimal places, for simplicity.

Note that these values are filled with respect to color scaled values. Also these limits clear upon change in variable or color scaling.

compute min/max from all data (default False):

True: all values present in a data variable are used to compute upper and lower colormap limits.

False: only values necessary to create first step/instance of graph are used.

It is better to have its value False for larger datasets, to save computation time.

colorbar (default True):
Provides option to display/hide colorbar.

rasterize (default True):
Provides option to use data shading . It is better to have its value True, to get highly optimized rendering.

Methods

setup_initial_values(self[, init_params])

To select initial values for the widgets in this pane.

setup_initial_values(self, init_params={})¶: To select initial values for the widgets in this pane.

Projection¶

Control¶

class xrviz.control.Control(data)¶

The user input part of the interface

Parameters

data: xarray.DataSet: The data to be visualised. Here, we are mostly concerned with displaying the variables, their attributes, and assigning coordinates to roles upon plotting.

Attributes

1. panel:: A panel.Tabs instance containing the user input panes
2. displayer:: A Display instance, displays a list of data variables for selection.
3. describer:: A Describe instance, describes the properties of the variable selected in the displayer.
4. coord_setter:: A CoordSetter instance for choosing which variables are considered coordinates.
5. fields:: A Fields instance to select the axes to plot with.
6. style:: A Style instance to customise styling of the graphs.
7. projection:: A Projection instance to customise the projection of geographical data.
8. kwargs:: A dictionary gathered from the widgets of the input Panes, of a form which can be passed to the plotting function as kwargs.

Methods

`check_is_projectable`(self, \*args)	Check if the selected variable can be projected geographically.
`set_coords`(self, data)	Called after coordinates have been set, to update the other input panes.

check_is_projectable(self, *args)¶

Check if the selected variable can be projected geographically.

This is possible only when both x and y are present in selected variable’s coordinates.

set_coords(self, data)¶: Called after coordinates have been set, to update the other input panes.

Dashboard¶

class xrviz.dashboard.Dashboard(data, initial_params={})¶

Main entry point to XrViz, an interactive GUI for a given dataset.

Parameters

data: xarray.DataSet: The data to be visualised
initial_params: `dict`: To pre-select values of widgets upon initialization. The keys are generally names of widgets within the input area of the interface. For more details, refer to Set Initial Parameters .

Attributes

1. panel:: A panel.Tabs instance containing the user input panes and output graphs of the interface.
2. control:: A Control instance responsible for input panes (control panel).
3. plot_button:: A pn.widgets.Button that generates graph according to values selected in input panes, upon click.
4. graph:: A HoloViews(DynamicMap) instance containing the main graph.
5. output:: The graph along with the select widgets for index selection.
6. taps_graph:: A holoviews.Points instance to record the location of taps.
7. series_graph:: A HoloViews(Overlay) instance having series extracted.
8. clear_series_button:: A pn.widgets.Button to clear the taps_graph and series_graph.

Methods

`check_is_plottable`(self, var)	Check if a data variable can be plotted.
`clear_series`(self, \*args)	Clears the markers on the image, and the extracted series.
`create_graph`(self, \*args)	Creates a graph according to the values selected in the widgets.
`create_indexed_graph`(self, \*args)	Creates a graph for the dimensions selected in widgets x and y.
`create_selectors_players`(self, graph)	Converts the sliders generated by hvplot into selectors/players.
`create_series_graph`(self, x, y, color[, clear])	Extract a series at a given point, and plot it.
`create_taps_graph`(self, x, y[, clear])	Create an output layer in the graph which responds to taps

check_is_plottable(self, var)¶

Check if a data variable can be plotted.

If a variable is 1-d, disable plot_button for it.

clear_series(self, *args)¶: Clears the markers on the image, and the extracted series.

create_graph(self, *args)¶

Creates a graph according to the values selected in the widgets.

This method is usually invoked by the user clicking “Plot”

It handles the following two cases:

1. Both x, y are present in selected variable’s coordinates. Geographic projection is possible only in this case. It uses create_selectors_players method for creation of the graph. Here the selectors generated automatically by hvplot are used.

2. One or both of x, y are NOT present in selected variable’s coordinates (both x and y are considered as dimensions). It uses create_indexed_graph method for creation of the graph. The selectors are created and linked with graph by XrViz.

create_indexed_graph(self, *args)¶

Creates a graph for the dimensions selected in widgets x and y.

This is used when values selected in x and y are not data coordinates (i.e. one or both values are data dimensions).

create_selectors_players(self, graph)¶

Converts the sliders generated by hvplot into selectors/players.

This is applicable only when both x and y are present in variable coordinates. It converts any sliders generated by hvplot into selectors/players and moves them to the bottom of graph.

create_series_graph(self, x, y, color, clear=False)¶

Extract a series at a given point, and plot it.

The series plotted has same color as that of the marker depicting the location of the tap.

The following cases have been handled:

Case 1:

When both x and y are NOT coords (i.e. are dims)

Case 2:

When both x and y are coords

2a: Both are 1-dimensional

2b: Both are 2-dimensional with same dimensions.

2c: Both are 2-dimensional with different dims or are multi-dimcoordinates. Here we are unable to extract.

Note that Case 1 and Case 2a can be handled with the same code.

create_taps_graph(self, x, y, clear=False)¶

Create an output layer in the graph which responds to taps

Whenever the user taps (or clicks) the graph, a glyph will be overlaid, and a series is extracted at that point.

Example¶

xrviz.example(show=True)¶

Generates interface for the sample dataset.

Parameters

show: bool (True): True: A new browser tab will be opened, and the function will block until interrupted. False: The Dashboard instance is returned without being executed.