Python- Day 12- Working with Part of a List in Python
You learned how to access individual items in a list. Now, let’s see how to work with groups of items using slices.
Slicing a List:
A slice is a part of a list. To create a slice, specify the start and end index. Python stops just before the end index. For example:
players = ['charles', 'martina', 'michael', 'florence', 'eli']
print(players[0:3])
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['charles', 'martina', 'michael']You can also select items from anywhere in the list:
print(players[1:4])
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['martina', 'michael', 'florence']Omitting Start or End Index:
If you leave out the start index, Python starts from the beginning:
print(players[:4])
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['charles', 'martina', 'michael', 'florence']If you omit the end index, it goes to the last item:
print(players[2:])
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['michael', 'florence', 'eli']Using Negative Indices:
Negative numbers can select items from the end of the list. For example:
print(players[-3:])
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['michael', 'florence', 'eli']Looping Through a Slice:
You can loop through a slice like this:
for player in players[:3]:
print(player.title())This will print the first three players’ names with their first letters capitalized.
Copying a List:
To copy a list, use a slice without specifying any indices:
my_foods = ['pizza', 'falafel', 'carrot cake']
friend_foods = my_foods[:]Now, both my_foods and friend_foods contain the same items.
You can confirm they’re separate by adding new items:
my_foods.append('cannoli')
friend_foods.append('ice cream')The lists are now different:
my_foods:['pizza', 'falafel', 'carrot cake', 'cannoli']friend_foods:['pizza', 'falafel', 'carrot cake', 'ice cream']
Be Careful When Copying Without a Slice:
If you assign a list directly without slicing, like this:
friend_foods = my_foodsBoth variables will point to the same list. Changes to one list will affect the other.
To avoid this, always use slicing ([:]) when you need a separate copy of a list.
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