Science

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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

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We found a big spider

Here is a big spider that we found while raking leaves today.

IMG_7041

Spiders are air-breathing arthropods.  They are found in every continent except Antarctica.

Spiders mostly prey on bugs, but few large species prey on large birds and lizards.  Argh, that is scary!

To find out more about spiders click here. http://en.wikipedia.org/wiki/Spider

That’s all for now.

 

Chemistry Photography
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Chemistry Photography

[Charcoal + Potassium Nitrate + Sulphur] when ground together in the right proportion, make … great photos!

Here is a scene from chemistry class.

 

First, we made charcoal by heating hardwood without oxygen.  This produces a lot of smoke, but in the end, all that’s left in the test tube is charcoal sticks.

Second, we ground the charcoal to a powder, and added a some potassium nitrate and sulphur.

Here is a spoonful of the fresh made black powder

Upon touching a hot coal to it, it ignited and combusted with a lot of smoke!

Quite bright!  This is a neat photograph (taken with Droid X)


 

(Proper safety precautions were taken during this class, including fire prevention and eye protection.  Do not repeat without appropriate knowledge and safety precautions in place)