Page 46 -

idle session

Lists in Python might look like arrays, but they are much more than that: they are full-blown Python collection
objects. This means that lists come with ready-to-use functionality in the form of list methods.
Let’s get to know some of Python’s list methods. Open up IDLE and follow along with the code entered at the >>>
prompt. You should see exactly the same output as shown here.
Start by defining a list of names, which you then display on screen using the print() BIF. Then, use the len()
BIF to work out how many data items are in the list, before accessing and displaying the value of the second data
item:
>>> cast = ["Cleese", 'Palin', 'Jones', "Idle"]
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle']
>>> print(len(cast)) It’s OK to invoke a BIF on
4 the results of another BIF.
>>> print(cast[1])
Palin
With your list created, you can use list methods to add a single data item to the end of your list (using the
append() method), remove data from the end of your list (with the pop() method), and add a collection of
data items to the end of your list (thanks to the extend() method):
Methods are invoked using the
>>> cast.append("Gilliam")
common “.” dot notation.
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam']
>>> cast.pop()
'Gilliam' It’s another list: items separated by commas,
>>> print(cast) surrounded by square brackets.
['Cleese', 'Palin', 'Jones', 'Idle']
>>> cast.extend(["Gilliam", "Chapman"])
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam', 'Chapman']

Finally, find and remove a specific data item from your list (with the remove() method) and then add a data item
before a specific slot location (using the insert() method):

>>> cast.remove("Chapman")
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam'] After all that, we end up with
>>> cast.insert(0, "Chapman") the cast of Monty Python’s
>>> print(cast) Flying Circus!
['Chapman', 'Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam']

10 Chapter 1