{"id":63,"date":"2022-04-12T23:46:21","date_gmt":"2022-04-12T23:46:21","guid":{"rendered":"https:\/\/codecrypt76.com\/?p=63"},"modified":"2022-11-25T16:49:57","modified_gmt":"2022-11-25T16:49:57","slug":"compare-adjacent-elements-in-a-list","status":"publish","type":"post","link":"https:\/\/codecrypt76.com\/index.php\/2022\/04\/12\/compare-adjacent-elements-in-a-list\/","title":{"rendered":"Compare Adjacent Elements in an Array"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

Introduction<\/h2>\n\n\n\n

This article will discuss how to compare adjacent elements in a List using Python. Suppose you want to create a new list from a given list by calculating the difference between adjacent elements of in the list, for example:<\/p>\n\n\n\n

Input<\/strong>: test_list = [26, 19, 12, 6]<\/p>

Output<\/strong>: new_list = [7, 7, 6]<\/p>

Explanation<\/strong>:

26 \u2013 19 = 7

19 \u2013 12 = 7

12 \u2013 6 = 6<\/p><\/blockquote>\n\n\n\n

There are several methods to achieve this. Each method demonstrated will use the same input list of [26, 19, 12, 6]<\/code> and produce the same output of [7, 7, 6]<\/code><\/p>\n\n\n\n

Method 1: Using the range()<\/code> function:<\/h2>\n\n\n\n
def adjacent_items(seq):\n    new_list = []\n    for i in range(1, len(seq)):\n        previous_item = seq[i - 1]\n        current_item = seq[i]\n        new_list.append(previous_item - current_item)\n\n    return new_list   # Output [7, 7, 6]<\/code><\/pre><\/div>\n\n\n\n
Method 2: Using the zip()<\/code> function and slices<\/code>:<\/h2>\n\n\n\n
def adjacent_items(seq):\n    new_list = []\n    list1 = seq[0::]  # Copy of list starting at index 0\n    list2 = seq[1::]  # copy of list starting at index 1       \n\n    for previous_item, current_item in zip(list1, list2):\n        new_list.append(previous_item - current_item)\n    return new_list  # Output [7, 7, 6]<\/code><\/pre><\/div>\n\n\n\n
Method 3: Using the zip()<\/code> function, slices<\/code>, and a list comprehension<\/code>:<\/h2>\n\n\n\n
new_list = [previous_item - current_item \n            for (previous_item, current_item) \n            in zip(test_list[0::], test_list[1::])]\nprint(new_list)  # Output [7, 7, 6]<\/code><\/pre><\/div>\n\n\n\n
Method 4: Using a generator<\/code> and list comprehension<\/code>:<\/h2>\n\n\n\n
First lets create the generator.<\/p>\n\n\n\n
def adjacent_items(seq):\n    iterable_list = iter(seq)\n    prev = next(iterable_list)\n    for item in iterable_list:\n        yield (prev - item)\n        prev = item<\/code><\/pre><\/div>\n\n\n\n