2.3. Part of a list
A specific group of items in a list is called a slice.
A specific group of items in a list is called a slice.
For example you want the first 3 elements of a list:
Notice that foods[0:3] return the foods with index 0, 1 and 2. As with the range(), Python don't include food with index 3.
If you want the 3rd, 4th, and 5th items in a list, you can start with index 2 and end with index 5.
If you omit the first index in a slice, it will automatically start at the beginning of the list:
Similarly, you can omit the second index if you want the rest of the list to be included:
You can also use negative index. Say we want to make a list of your 3 last orders:
In the last example, say we want to print our last 3 orders using for loop. We can use the slice in for loop as well as follows:
To copy a list, you can use a slice of the original list with both indexes omitted (like this foods[:]). This is basically a copy of the original list.
Say your friend order some additional foods and you also decided to order extra food. Here, you order an ice cream while your friend order a fried chicken.
This way you can make a copy of whatever list you want. However, if you don't put [:] when you assign a copy, the variable my_orders and friend_orders will be the same, resulting undesired orders at the end. Try it out!
Slices
From the list of stationary do the following:
Use a slice to print the first three items from that list as follows:
The first three items in the list are:
pen pencil eraser
Hint: Use end=" "
Use a slice to print the third to sixth items from that list as follows:
The third to sixth items in the list are:
eraser ruler highlighter calculator
Use a slice to print the last four items in the list as follows:
The last four items in the list are:
sharpener compass cutter marker
My Stationary, Your Stationary
Using the previous stationary list, make a new copy of that list, call it friends_stationary.
Delete the last item in my_stationary list using del then add "stapler" to the beginning of the list using insert().
Delete the first item in friends_stationary list then add "correction tape" to the list using append().
Prove that you have two separate lists. Print the message
My items are:
and then use a for loop to print the first list.
Print the message
My friend's items are:
and then use a for loop to print the second list. Make sure each new items is stored in the appropriate list.