Function that is agnostic to object implementing len() or shape

Question

I have a function func(x) which expects a parameter x. x should be some kind of collection or array. func(x) needs to get the length of x:

 def func(x):        
    for i in range(len(x)):
        print('Something', i)

The problem is that some collection-like objects have len() implemented but not .shape (e.g. a list) others have .shape implemented but not len() (e.g. a sparse matrix). What is the most pythonic way to make func(x) work, regardless of this issue? Or are there other things to consider when looking for a solution for this problem?

What I can think of:

• Expecting another parameter: func(x, length_of_x)

• Calling a different function altogether

• Catching missing implementation with try-except:

   import numpy as np
   from scipy.sparse import csr_matrix
   def func(x):
       try:
           length_of_x = len(x)
       except:
           length_of_x = x.shape[0]
  
       for i in range(length_of_x):
           print('Something', i)
  
   func([1, 2, 3])
  
   sparse_matrix = csr_matrix(([1, 2, 3, 4, 5, 6], ([0, 0, 1, 2, 2, 2], [0, 2, 2, 0, 1, 2])))
   func(sparse_matrix)
  

• if-else Block

   def func(x):
       if isinstance(x, csr_matrix):
           length_of_x = x.shape[0]
       else:
           length_of_x = len(x)   
       for i in range(length_of_x):
           print('Something', i)
  

Answer 1

The most Pythonic way to approach would be to build the internal logic using iterators rather than indexes.

def func(x):        
    for value in x:
        print('Something', value)