CODEWITHSUNDEEP
pythonarraysnumpy
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Reputation: 8396

Get the three minimum values of an array in Python, ignoring a value

If I have the following array: a = [4, -5, 10, 4, 4, 4, 0, 4, 4]

To get the three minimum values index I do:

a1 = np.array(a) 
print a1.argsort()[:3]

This outputs the following, which is ok:

[1 6 0]

The thing is that this includes that -5 (index 1).

How can I do this exact thing but ignoring the -5 of the array?

Upvotes: 0

Views: 2975

Answers (2)

loopbackbee
loopbackbee

Reputation: 23322

If you're looking to exclude the minimum element, you can simply skip the element while slicing:

>>> a = [4, 3, 10, -5, 4, 4, 4, 0, 4, 4]
>>> a1 = np.array(a) 
>>> minimum_indexes= a1.argsort()[1:4]
>>> print a1[minimum_indexes]
[0 3 4]

Upvotes: 2

user861537
user861537

Reputation:

You can filter out your specific number after argsort:

>>> a = [4, -5, 10, 4, 4, 4, 0, 4, 4]
>>> a1 = np.array(a) 
>>> indices = a1.argsort()
>>> indices = indices[a1[indices] != -5]
>>> print(indices[:3])
[6 0 3]

It's easy to change your condition. For instance, if you want to filter out all negative numbers, then use the following line instead:

>>> indices = indices[a1[indices] >= 0]

Upvotes: 2

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