VisPy Sinewave Demo

VisPy is quite an interesting tool.  They say it is for “scientific visualization”.  Here is an example of that.  I took a demo from their github page and added a little code to generate a sinewave.  The cool thing is that the graph, scaling, panning, zooming, and redrawing all come out of the box.

I previously wrote about installing VisPy.  Thanks to the great efforts of some unnamed people, Python on Windows is really working nicely now.

Here is a screenshot:

vis

Here is the code:

# -*- coding: utf-8 -*-
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
"""
Demonstration of InfiniteLine visual.
"""
import sys
import numpy as np
from vispy import app, scene
# vertex positions of data to draw
N = 200
pos = np.zeros((N, 2), dtype=np.float32)
x_lim = [50., 1750.]
y_lim = [2., 2.]
pos[:, 0] = np.linspace(x_lim[0], x_lim[1], N)
pos[:, 1] = np.random.normal(size=N)
pos1 = np.zeros((20000,2), dtype=np.float32)
color1 = np.ones((20000,4), dtype=np.float32)
pos1[0,0] = 0.0
pos1[0,1] = 15.0
pos1[1,0] = 100.0
pos1[1,1] = 15.0
import math
for x in range(20000):
pos1[x,0] = x*10
pos1[x,1] = math.sin(x/20.) * 40.
# color array
color = np.ones((N, 4), dtype=np.float32)
color[:, 0] = np.linspace(0, 1, N)
color[:, 1] = color[::1, 0]
canvas = scene.SceneCanvas(keys='interactive', show=True)
grid = canvas.central_widget.add_grid(spacing=0)
viewbox = grid.add_view(row=0, col=1, camera='panzoom')
# add some axes
x_axis = scene.AxisWidget(orientation='bottom')
x_axis.stretch = (1, 0.1)
grid.add_widget(x_axis, row=1, col=1)
x_axis.link_view(viewbox)
y_axis = scene.AxisWidget(orientation='left')
y_axis.stretch = (0.1, 1)
grid.add_widget(y_axis, row=0, col=0)
y_axis.link_view(viewbox)
# add a line plot inside the viewbox
#line = scene.Line(pos, color, parent=viewbox.scene)
line1 = scene.Line(pos1, color1, parent=viewbox.scene)
# add vertical lines
vert_line1 = scene.InfiniteLine(100, [1.0, 0.0, 0.0, 1.0],
parent=viewbox.scene)
vert_line2 = scene.InfiniteLine(549.2, [0.0, 1.0, 0.0, 1.0], vertical=True,
parent=viewbox.scene)
# add horizontal lines
hor_line1 = scene.InfiniteLine(0.3, [1.0, 0.0, 1.0, 1.0], vertical=False,
parent=viewbox.scene)
hor_line2 = scene.InfiniteLine(5.1, [1.0, 1.0, 0.0, 1.0], vertical=False,
parent=viewbox.scene)
# auto-scale to see the whole line.
viewbox.camera.set_range((0,1000), (100,100))
if __name__ == '__main__' and sys.flags.interactive == 0:
app.run()

view raw
vis.py
hosted with ❤ by GitHub

Installing VisPy on Windows 10

VisPy is a Python library for interactive scientific visualization that is designed to be fast, scalable, and easy to use.

Here is how I installed it:

First I installed the latest Python 3.6 on Windows 10 by following the directions on http://www.python.org.  Once this was installed, I opened up Windows PowerShell and ran this command:

py -m pip upgrade vispy PyQt5 --user

I found some sample code here, and using NotePad++, copied and pasted it, saving it to Desktop\Code\v1.py

https://github.com/vispy/vispy/blob/master/examples/basics/gloo/animate_shape.py

In PowerShell, I changed to the directory that I saved the python code to and ran it:

cd Desktop\Code
py .\v1.py

Here is the output:

zzzz

It’s a pretty smooth and clean looking UI.  It seems extremely powerful, but I’ll need to dig in and see what makes it tick…