Curveedit¶

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Title: CurveEdit Stream¶

Description: A linked streams example demonstrating how to use the CurveEdit stream.

Dependencies: Bokeh

Backends: Bokeh

In [1]:

import numpy as np
import holoviews as hv

from holoviews import opts, streams
from holoviews.plotting.links import DataLink

hv.extension('bokeh')

The CurveEdit stream adds a bokeh tool to the source plot, which allows drawing, dragging and deleting points and making the drawn data available to Python. The tool supports the following actions:

Move vertex

Tap and drag an existing vertex, the vertex will be dropped once you let go of the mouse button.

Delete vertex

Tap a vertex to select it then press BACKSPACE or DELETE key while the mouse is within the plot area.

As a simple example we will create a CurveEdit stream and attach it to a Curve with a simple timeseries. By using a DataLink we then link the tool to a Table.

If we select the PointDraw tool () the vertices will appear and allow us to drag and delete vertex. We can also see the x/y position change in the table and edit it. To change the appearance of the vertices we can supply a style to the CurveEdit stream:

In [2]:

curve = hv.Curve(np.random.randn(10).cumsum())

curve_stream = streams.CurveEdit(data=curve.columns(), source=curve, style={'color': 'black', 'size': 10})

table = hv.Table(curve).opts(editable=True)
DataLink(curve, table)

(curve + table).opts(
    opts.Table(editable=True))

Out[2]:

Whenever the data source is edited the data is synced with Python, both in the notebook and when deployed on the bokeh server. The data is made available as a dictionary of columns:

In [3]:

curve_stream.data

Out[3]:

{'x': [0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0],
 'y': [-1.018198262241648,
  -1.8426017242302115,
  -0.944548282170297,
  -1.8065860611333613,
  -0.2625012877901727,
  -0.8140448002519592,
  0.2724089162503015,
  0.647983503118186,
  -1.1894524402441744,
  -0.8307604706301885]}

Alternatively we can use the element property to get an Element containing the returned data:

In [4]:

curve_stream.element

Out[4]:

Download this notebook from GitHub (right-click to download).