What is the Matlab equivalent to Python's `not in`?

Question

In Python, one could get elements that are exclusive to lst1 using:

lst1=['a','b','c']
lst2=['c','d','e']
lst3=[]
for i in lst1:
    if i not in lst2:
        lst3.append(i)

What would be the Matlab equivalent?

Answer 1

You are looking for MATLAB's setdiff -

setdiff(lst1,lst2)

Sample run -

>> lst1={'a','b','c'};
>> lst2={'c','d','e'};
>> setdiff(lst1,lst2)
ans = 
    'a'    'b'

Verify with Python run -

In [161]: lst1=['a','b','c']
     ...: lst2=['c','d','e']
     ...: lst3=[]
     ...: for i in lst1:
     ...:     if i not in lst2:
     ...:         lst3.append(i)
     ...:         

In [162]: lst3
Out[162]: ['a', 'b']

In fact, you have setdiff in Python's NumPy module as well, as numpy.setdiff1d. The equivalent implementation with it would be -

In [166]: import numpy as np

In [167]: np.setdiff1d(lst1,lst2) # Output as an array
Out[167]: 
array(['a', 'b'], 
      dtype='|S1')

In [168]: np.setdiff1d(lst1,lst2).tolist() # Output as list
Out[168]: ['a', 'b']