Holoview

Note

This is user-contributed content. Credits go to Dr. A. Khalatyan (researcher at IT-eScience, AIP, Potsdam)!

Bokeh / DASK server

The combination of the Bokeh, DASK and Holoview is allowing us to interactively render large datasets. This example is deploying an interactive visualization of a DASK dataframe via a Holoview application:

create a file named server_app.py:

import os
import dask.dataframe as dd
import holoviews as hv
import pandas as pd
import numpy as np
from holoviews.operation.datashader import datashade

hv.extension('bokeh')

# 1. Load data
## load from a parquet file:
#ddf = dd.read_parquet("data.parq")[['xgal', 'ygal']].persist()

# or let's just generate some random data for demo
df = pd.Dataframe({
    'xgal': np.random.randn(1000),
    'ygal': np.random.randn(1000)
})
ddf = dd.from_pandas(df)

# 2. Datashade it

points = hv.Points(ddf, kdims=['xgal', 'ygal'])
shaded = datashade(points).opts(plot=dict(width=800, height=600))

# 3. Instead of Jupyter's automatic rich display, render the object as a bokeh document
doc = hv.renderer('bokeh').server_doc(shaded)
doc.title = 'HoloViews Bokeh App'

in terminal start the Bokeh server:

bokeh serve --disable-index-redirect --allow-websocket-origin='*' --port 5006 server_app.py

now your interactive plot is accessible on following URL:

https://cocalc.com/[PROJECT_ID]/server/5006/server_app

or run this line in a terminal to get the URL and click on it:

echo "https://cocalc.com/$COCALC_PROJECT_ID/server/5006/server_app"

Holoview App

For deploying an interactive plots based on Bokeh, Panel, Holoviz or similar libraries we can use the server feature of CoCalc, like in the examples for the Tensorboard:

Create a python file holo.py. (If you are using a self hosted instance, replace cocalc.com with your domain):

import holoviews as hv
import panel as pn
import numpy as np

hv.extension('bokeh')

def sine(frequency, phase, amplitude):
    xs = np.linspace(0, np.pi*4)
    return hv.Curve((xs, np.sin(frequency*xs+phase)*amplitude)).options(width=800)

if __name__ == '__main__':
    ranges = dict(frequency=(1, 5), phase=(-np.pi, np.pi), amplitude=(-2, 2), y=(-2, 2))
    dmap = hv.DynamicMap(sine, kdims=['frequency', 'phase', 'amplitude']).redim.range(**ranges)
    pn.serve(dmap, port=8006, allow_websocket_origin=["cocalc.com"], show=False)

Start it in the terminal:
```
python3 holo.py
```
now your interactive Holoview application is available in the following URL:
```
https://cocalc.com/[PROJECT_ID]/server/8006/
```
or run this line in a terminal to get the URL and click on it:
```
echo "https://cocalc.com/$COCALC_PROJECT_ID/server/8006/"
```