Time for action – clipping and compressing arrays

Here are a few examples of ndarray methods. Perform the following steps to clip and compress arrays:

1. The clip method returns a clipped array, so that all values above a maximum value are set to the maximum and values below a minimum are set to the minimum value. Clip an array with values 0 to 4 to 1 and 2.

   a = np.arange(5)
   print "a =", a
   print "Clipped", a.clip(1, 2)

   This gives the following output:

   a = [0 1 2 3 4]
   Clipped [1 1 2 2 2]

2. The ndarray compress method returns an array based on a condition. For instance, look at the following code:

   a = np.arange(4)
   print a
   print "Compressed", a.compress(a > 2)

   This returns the following output:

   [0 1 2 3]
   Compressed [3]

What just happened?

We created an array with values 0 to 3 and selected the last element with the compress function based on the condition a > 2.