Thursday, December 13, 2012

Waiting for NumPy Cookbook

Also this year the Packt Publishing gives me the opportunity to review an interesting book about scientific computing in Python. The last year I had the pleasure to review Numpy 1.5 Beginner's Guide from Ivan Idris and I was surprised about the number of code examples and the straightforward approach to the explanation of the topics. Now I am waiting for Numpy Cookbook, which is from the same author and I can't wait to write the review. Stay tuned ;)

Thursday, December 6, 2012

3D stem plot

A two-dimensional stem plot displays data as lines extending from a baseline along the x axis. In the following snippet we will see how to make a three-dimensional stem plot using the mplot3d toolkit. In this case we have that data is displayed as lines extending from the x-y plane along the z direction.Let's go with the code:
from numpy import linspace, sin, cos
from pylab import figure, show
from mpl_toolkits.mplot3d import Axes3D

# generating some data
x = linspace(-10,10,100);
y = sin(x);
z = cos(x);

fig = figure()
ax = Axes3D(fig)

# plotting the stems
for i in range(len(x)):
  ax.plot([x[i], x[i]], [y[i], y[i]], [0, z[i]], 
          '--', linewidth=2, color='b', alpha=.5)

# plotting a circle on the top of each stem
ax.plot(x, y, z, 'o', markersize=8, 
        markerfacecolor='none', color='b',label='ib')


And this is the result