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pythonnumpysizeunique

Get number of elements after using np.unique Python

I e got a set of elemnt. the task is to get the number of unique elements. I wrote the following:

 import numpy as np
 tokens1 = set(["a", "b", "c", "c"])
 print(np.unique(tokens1))
 print(np.unique(tokens1).size)

The result is 

[{'c', 'b', 'a'}]
1

How do i get the correct number - 3? Should have i simply used something other than np.unique in the first place? there might be a better way to get hat i want.

Solution

  • In order to get the number of unique elements in a set, you can simply call len() on the set. To modify your existing code:

    tokens1 = set(["a", "b", "c", "c"])
print(len(tokens1))
# prints: 3

    This is because a set already removes duplicates. You don't need to use both a set AND np.unique().

    If you wanted to use np.unique() instead, you could modify your code to be:

    tokens1 = np.unique(["a", "b", "c", "c"])
print(len(tokens1))
# prints: 3