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Create Your Own ufunc


How To Create Your Own ufunc

To create you own ufunc, you have to define a function, like you do with normal functions in Python, then you add it to your NumPy ufunc library with the frompyfunc() method.

The frompyfunc() method takes the following arguments:

  1. function - the name of the function.
  2. inputs - the number of input arguments (arrays).
  3. outputs - the number of output arrays.

Example

Create your own ufunc for addition:

import numpy as np

def myadd(x, y):
  return x+y

myadd = np.frompyfunc(myadd, 2, 1)

print(myadd([1, 2, 3, 4], [5, 6, 7, 8]))
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Check if a Function is a ufunc

Check the type of a function to check if it is a ufunc or not.

A ufunc should return <class 'numpy.ufunc'>.

Example

Check if a function is a ufunc:

import numpy as np

print(type(np.add))
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If it is not a ufunc, it will return another type, like this built-in NumPy function for joining two or more arrays:

Example

Check the type of another function: concatenate():

import numpy as np

print(type(np.concatenate))
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If the function is not recognized at all, it will return an error:

Example

Check the type of something that does not exist. This will produce an error:

import numpy as np

print(type(np.blahblah))
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To test if the function is a ufunc in an if statement, use the numpy.ufunc value (or np.ufunc if you use np as an alias for numpy):

Example

Use an if statement to check if the function is a ufunc or not:

import numpy as np

if type(np.add) == np.ufunc:
  print('add is ufunc')
else:
  print('add is not ufunc')
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