Subtracting items inside arrays

Question

I have this array:

array = [1 1 2 3 5 8]

How do I get the difference between adjacent items so that I'll obtain this array:

diff = [0 1 1 2 3]

So far, this has been my attempt but I know why this doesn't work bc i and h are not really integers

array = []
diff = []


for i in array:
         h = i - 1     # h is not int() here coz it's not an index
         if h >= 0:
              j = i.get() - h.get()
              diff.append(j)
         else:
              pass

I'm newbie in programming, thoughts you'll share will be appreciated

Why is `array` empty? Why do you say `h` is not an int? If it's a list (not array) of ints then `h` is an int... — Tomerikoo, Oct 21 '21 at 11:13
You can make your code work by simply changing the loop to `for i in range(len(array))` and changing `i.get()` and `h.get()` to `array[i]` and `array[h]` respectively — Tomerikoo, Oct 21 '21 at 11:19

score 2 · Answer 1 · answered Oct 21 '21 at 11:13

2

You can use zip function.

>>> array = [1, 1, 2, 3, 5, 8]
>>> [j - i for i, j in zip(array, array[1:])]
[0, 1, 1, 2, 3]

answered Oct 21 '21 at 11:13

Abdul Niyas P M

18,035
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score 0 · Accepted Answer · answered Oct 21 '21 at 11:14

The most straight forward way is to either use the index directly with range or use enumerate to get both the index and the current value. With range:

a = [1, 1, 2, 3, 5, 8]
b = []

for i in range(1, len(a)):  # i = 1 -> length of a
  b.append(a[i] - a[i-1])  # add the difference between this element and the element before it to `b`

>>> b
[0, 1, 1, 2, 3]

score -1 · Answer 3 · answered Oct 21 '21 at 11:13

-1

diff = [array[i + 1] - array[i] for i in range(len(array) - 1)]

answered Oct 21 '21 at 11:13

11_22_33

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Subtracting items inside arrays

3 Answers3