python slice an array
a[start:stop] # items start through stop-1
a[start:] # items start through the rest of the array
a[:stop] # items from the beginning through stop-1
a[:] # a copy of the whole array
Example:
>>> a = [1, 2, 3, 4, 5, 6, 7, 8]
>>> a[1:4]
[2, 3, 4]python how to slice lists
# Basic syntax:
your_list[start:stop:step]
# Note, Python is 0-indexed
# Note, start is inclusive but stop is exclusive
# Note, if you leave start blank, it defaults to 0. If you leave stop
# blank, it defaults to the length of the list. If you leave step
# blank, it defaults to 1.
# Note, a negative start/stop refers to the index starting from the end
# of the list. Negative step returns list elements from right to left
# Example usage:
your_list = [0, 1, 2, 3, 4, 5]
your_list[0:5:1]
--> [0, 1, 2, 3, 4] # This illustrates how stop is not inclusive
# Example usage 2:
your_list = [0, 1, 2, 3, 4, 5]
your_list[::2] # Return list items for even indices
--> [0, 2, 4]
# Example usage 3:
your_list = [0, 1, 2, 3, 4, 5]
your_list[1::2] # Return list items for odd indices
--> [1, 3, 5]
# Example usage 4:
your_list = [0, 1, 2, 3, 4, 5]
your_list[4:-6:-1] # Return list items from 4th element from the left to
# the 6th element from the right going from right to left
--> [4, 3, 2, 1]
# Note, from the right, lists are 1-indexed, not 0-indexedCopyright © 2021 Codeinu
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