Finding the differences between integers in the list

Question

After much tinkering, I have finally come up with a piece of code that takes the differences between each of the integers in the same list, and dumps them into a new list. Here's my code:

ints = [3, 5, 9, 15, 36]
difs = []
h = 0

while h < len(ints) - 1:    
    difs.append(ints[1 + h] - ints[0 + h])
    h = h + 1
print difs  

When run, the list 'difs' contains [2, 4, 6, 21] (ie the differences between the integers in the 'int' list.

My question: is there any even simpler function--perhaps in numpy--that does this automatically?

Answer 1

There is a function in numpy : numpy.diff() .

>>> import numpy
>>> numpy.diff([3, 5, 9, 15, 36])
array([ 2,  4,  6, 21])

Answer 2

Using list comprehension with zip :

>>> ints = [3, 5, 9, 15, 36]
>>> [b-a for a, b in  zip(ints, ints[1:])]
[2, 4, 6, 21]

Answer 3

Yes, There is a function diff() in numpy. It can be used like this...

ints = [3, 5, 9, 15, 36]
x = numpy.array(ints)

numpy.diff(x)

output:

[2, 4, 6, 21]  

You can also use the same function to get the difference between two lists using axis parameter in the function.