Question

What is the best way to touch two following values in an numpy array?

example:

npdata = np.array([13,15,20,25])
for i in range( len(npdata) ):
    print npdata[i] - npdata[i+1]

this looks really messed up and additionally needs exception code for the last iteration of the loop.
any ideas?

Thanks!

Answer 1

numpy provides a function diff for this basic use case

>>> import numpy
>>> x = numpy.array([1, 2, 4, 7, 0])
>>> numpy.diff(x)
array([ 1,  2,  3, -7])

Your snippet computes something closer to -numpy.diff(x).