SciPy

The SciPy library is part of the “SciPy ecosystem” that also includes NumPy, Sympy, and Pandas. We will not discuss Sympy but it is a well-developed computer algebra system (CAS) that is also incorporated into several other packages such as SageMath. Its homepage at www.scipy.org has details and documentation.

Importing SciPy Packages

Importing from scipy alone brings only the base packages, which provide a fairly minimal set of tools. Individual packages must be imported explicitly.

from scipy import linalg, optimize

For an imported package, type help(name) to see a summary of available functions.

help(linalg)

Exercises

Type in the following code to solve a linear system of equations.

import numpy as np
from scipy import linalg
A = np.array([[1, 2], [3, 4]])
b = np.array([[5], [6]])
c=linalg.solve(A, b)
print(c)

See examples of simple image processing here and here and here as well as many other sites. Use the SciPy ndimage to tint a photograph.

1. Import numpy and matplotlab.pyplot. Import the scipy misc package
2. Extract the sample picture “face” (a raccoon).
3. Use matplotlab function imshow to look at the picture. You may still need to use plt.show().
4. Use the NumPy array(img) function to get a numpy array. Specify dtype=‘float’.
5. Get the shape of the image array.
6. Tone down the blue by .9 and the red by .95. The order of color channels in the image is RBG.
7. The multiplication will use floats which are not permitted for an image (the pixel values must be integers between 0 and 255). Store the tinted array into a new array with dtype=‘int’. You can do this in one step if you think about it.
8. Show the new image. If you use plt.figure() and only one plt.show() you can view the images side by side.

import numpy as np
import matplotlib.pyplot as plt
from scipy import misc

plt.figure()
image=misc.face()
plt.imshow(image)

img_array=np.array(image,dtype='float')
print(img_array.shape)

retint=np.array(img_array*[0.95,0.9,1.0],dtype='int')

plt.figure()
plt.imshow(retint)
plt.show()

Resources

The SciPy reference guide is an invaluable resource for SciPy usage.