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.

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