Notebook

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import panel as pn
import pandas as pd
import numpy as np

pn.extension('perspective')

The Perspective pane provides an interactive visualization component for large, real-time datasets built on the Perspective project.

Parameters:¶

For layout and styling related parameters see the customization user guide.

aggregates (dict): Aggregation spec, e.g. {x: "distinct count"}
columns (list): List of displayed columns.
computed_columns (list): List of computed columns, e.g. ['"x"+"y"']
column_pivots (list): A list of columns to pivot by. e.g. ["x", "y"]
filters (list): A list of filters, e.g. [["x", "<", 3], ["y", "contains", "abc"]].
object (dict or pd.DataFrame): The plot data declared as a dictionary of arrays or a DataFrame.
row_pivots (list): List of columns to group by, e.g. ["x", "y"]
selectable (bool, default=True): Whether rows are selectable
sort (list): List of sorting specs, e.g. [["x", "desc"]]
plugin (str): The name of a plugin to display the data. For example hypergrid or d3_xy_scatter.
toggle_config (bool): Whether to show the config menu.
theme (str): The theme of the viewer, available options include 'material', 'material-dark', 'material-dense', 'material-dense-dark' and 'vaporwave'

The Perspective pane renders columns of data specified as a dictionary of lists or arrays and pandas DataFrames:

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data = {'x': [1, 2, 3], 'y': [1, 2, 3]}

pn.pane.Perspective(data)

We can also set the various config settings such as choosing the columns to display or the theme from Python:

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df = pd.DataFrame(np.random.randn(400, 4), columns=list('ABCD')).cumsum()

perspective = pn.pane.Perspective(
    df, plugin='d3_y_line', columns=['A', 'B', 'C', 'D'], theme='material-dark',
sizing_mode='stretch_width', height=500, margin=0)

perspective

The Perspective pane also supports stream and patch methods allowing us to efficiently update the data. The amount of data to keep in the streaming buffer can be controlled via the rollover option:

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rollover = pn.widgets.IntInput(name='Rollover', value=500)

def stream():
    data = df.iloc[-1] + np.random.randn(4)
    perspective.stream(data, rollover.value)

cb = pn.state.add_periodic_callback(stream, 50)

pn.Row(cb.param.period, rollover)

Alternatively we can also patch the data:

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mixed_df = pd.DataFrame({'A': np.arange(10), 'B': np.random.rand(10), 'C': [f'foo{i}' for i in range(10)]})

perspective = pn.pane.Perspective(mixed_df)

perspective

The easiest way to patch the data is by supplying a dictionary as the patch value. The dictionary should have the following structure:

{
    column: [
        (index: int or slice, value),
        ...
    ],
    ...
}

As an example, below we will patch the 'A' and 'C' columns. On the 'A' column we will replace the 0th row and on the 'C' column we replace the first two rows:

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perspective.patch({'A': [(0, 3)], 'C': [(slice(0, 1), 'bar')]})