Creating a universal function

We can create a universal function from a Python function with the NumPy frompyfunc function.

How to do it...

The following steps let us create a universal function:

1. Define the Python function.

   Let's define a simple Python function that just doubles the input:

   def double(a):
       return 2 * a

2. Create the universal function.

   Create the universal function with frompyfunc. We need to specify the number of input arguments and the number of objects returned:

   import numpy
   
   def double(a):
      return 2 * a
   
   ufunc = numpy.frompyfunc(double, 1, 1)
   print "Result", ufunc(numpy.arange(4))

   The code prints the following output, when executed:

   Result [0 2 4 6]
   

How it works...

We defined a Python function, which doubles the numbers it receives. Actually, we could also have strings as input, because that is legal in Python. We created a universal function from this Python function with the NumPy frompyfunc function.