python - Ensure that an array has all values encoded as 1 and -1, not 1 and 0

Question

There is a 1 dimensional numpy array named "target_y". My task is to ensure that "target_y" has all values encoded as 1 and -1, not 1 and 0 before performing logistic regression. Once I do it, I need to assign it to "prepared_y" and return it. Can I write something like:

if target_y in 1,-1:
    prepared_y = target_y 

question from:https://stackoverflow.com/questions/65647762/ensure-that-an-array-has-all-values-encoded-as-1-and-1-not-1-and-0

Answer 1

To replace all 0 values with -1 in a numpy.array it’s as simple as:

a[a == 0] = -1

... where a is the 1 dimensional array.