python方式访问numpy数组的移位版本？

Question

What is a pythonic way to access the shifted, either right or left, of a numpy array? A clear example:

a = np.array([1.0, 2.0, 3.0, 4.0])

Is there away to access:

a_shifted_1_left = np.array([2.0, 3.0, 4.0, 1.0])

from the numpy library?

Answer 1

You are looking for np.roll -

np.roll(a,-1) # shifted left
np.roll(a,1) # shifted right

Sample run -

In [28]: a
Out[28]: array([ 1.,  2.,  3.,  4.])

In [29]: np.roll(a,-1) # shifted left
Out[29]: array([ 2.,  3.,  4.,  1.])

In [30]: np.roll(a,1) # shifted right
Out[30]: array([ 4.,  1.,  2.,  3.])

If you want more shifts, just go np.roll(a,-2) and np.roll(a,2) and so on.