Idr Idr - 6 months ago 38
Python Question

Shift all indices in NumPy array

I have a numpy array like this:

x=np.array([0,1,2,3,4])


and want to create an array where the value in index 0 is in index 1, index 1 is in index 2, etc.

The output I want is:

y=np.array([0,0,1,2,3]).


I'm guessing there's an easy way to do this without iterating through the full array. How can I do this in a numPythonic way?

Answer

You can use

y = numpy.roll(x, 1)
y[0] = 0

or

y = numpy.r_[0, x[:-1]]
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