[Python] Sliding window tutorial

sliding_window_tutorial.py

# sliding_window_tutorial.py

# We have an array, a.k.a. a list.
my_array = [1, 2, 3, 4, 5,
            6, 7, 8, 9, 10,
            11, 12, 13, 14, 15,
            16, 17, 18, 19, 20]
print("my_array: %s" % my_array)
print()
# my_array: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

# The idea: build the resulting array from taking one element out at a time.

# Cycle through all the elements, using 'range' and 'len'
for i in range(len(my_array)):
    print("i=%s" % i)

    # bottom: my_array[:i] means "all the elements up to the one of index i"
    #  e.g.
    #   i=0               i=1                i=2                   ..etc..
    #   bottom_slice: []  bottom_slice: [1]  bottom_slice: [1, 2]  ..etc..
    bottom_slice = my_array[:i]

    # top: my_array[i+1:] means "all the elements starting from i+1"
    top_slice = my_array[i + 1:]

    # This combo skips the item of index i, in the current loop iteration.
    # Time to build our "one-out array".

    # Because '.extend' works in-place and returns 'None', I make a new
    #  array on which to operate. To do so, I use the generator syntax
    #  of Python:  '[i for i in bottom_slice]'

    # This will generate a list of items i from the items of bottom_slice.
    #  It's a way of writing a copy of another list.
    one_out_array = [i for i in bottom_slice]

    # '.extend' appends items, taking a list as input instead of the single item
    #  to append. So, I give a copy of 'top_slice' as input to '.extend'
    one_out_array.extend([i for i in top_slice])

    # So far, we have built our "one-out array".

    # Save the "one-out element".
    the_one_out = my_array[i]

    # Print the result for your joy
    print("bottom_slice: %s" % bottom_slice)
    print("top_slice: %s" % top_slice)
    print("one_out_array: %s" % one_out_array)
    print("the_one_out: %s" % the_one_out)

    # Print one extra line for extra space and go on for the next iteration
    print()