CODEWITHSUNDEEP
pythonarrayspython-3.xnumpy
Nelly
Nelly

Reputation: 81

How can I transform my array to 0 or 1 elements?

[[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
 [0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
 [0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
 [0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
 [0 1 1 1 0 0 0 0 0 1 1 0 0 3 3 0 0 0 4 4 0 0 0 5 5 5 5 0 0 2 2 2 2 2 0 2 2 2 2 2 0 0 0 6 6 6 6 6 6 0 6 6 6 6]
 [0 1 1 0 0 0 0 0 0 0 0 0 0 3 3 0 0 0 4 4 0 0 5 5 5 5 5 5 0 2 2 2 2 2 2 2 2 2 2 2 2 0 0 6 6 6 6 6 6 6 6 6 6 6]
 [1 1 1 0 0 0 0 0 0 0 0 0 0 3 3 0 0 0 4 4 0 5 5 5 0 0 5 5 5 0 2 2 0 0 2 2 0 0 0 2 2 0 0 6 6 0 0 6 6 6 0 0 6 6]
 [1 1 1 0 0 0 0 0 0 0 0 0 0 3 3 0 0 0 4 4 0 5 5 5 5 0 0 0 0 0 2 2 0 2 2 2 0 0 0 2 2 2 0 6 6 0 0 0 6 6 0 0 6 6]
 [1 1 1 0 0 0 0 0 0 0 0 0 0 3 3 0 0 0 4 4 0 0 5 5 5 5 5 5 0 0 2 2 0 2 2 2 0 0 0 2 2 2 0 6 6 0 0 0 6 6 0 0 6 6]
 [0 1 1 0 0 0 0 0 0 7 0 0 0 3 3 0 0 0 4 4 0 0 0 0 5 5 5 5 5 0 2 2 0 2 2 2 0 0 0 2 2 2 0 6 6 0 0 0 6 6 0 0 6 6]]

what i want is to change the value of every none 0 number to 1.

what i can do:

for element in list:
    for sub_element in element:
        if sub_element != 0:
           sub_element = 1

How can i do that in numpy?

Upvotes: 1

Views: 316

Answers (2)

jpp
jpp

Reputation: 164613

Given a NumPy array A:

res = A.astype(bool).astype(int)

For efficiency, and most use cases, you can keep your array as Boolean, omitting the integer conversion.

This works because 0 is the only integer considered False; all others are True. Converting a Boolean array to int is then a trivial mapping of False to 0 and True to 1.

Upvotes: 2

Jan Spurny
Jan Spurny

Reputation: 5528

If your numpy array is named a, you can use something like this:

a[a!=0.0] = 1

proof:

>>> a = numpy.array([0.0, 1.0, 2.0, 3.0, 0.0, 10.0])
>>> a
array([  0.,   1.,   2.,   3.,   0.,  10.])
>>> a[a!=0.0] = 1
>>> a
array([ 0.,  1.,  1.,  1.,  0.,  1.])

This works because a != 0.0 will return array with True/False values where the condition is met and then the assignment is performed only on those elements where there is True:

>>> a != 0
array([False,  True,  True,  True, False,  True], dtype=bool)

Also, this works with any other condition.

Upvotes: 5

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