List Methods

Let's explore some basic techniques to work with lists:

len(t) - returns the length of list t, or in other words, the number of items it contains;
list1 + list2 - combines two lists (both must be lists);
t * n - creates n duplicates of list t;
t.append(x) - adds a single item x to the end of list t (this alters the original list);
t.extend([x, y, ...]) - appends elements x, y, ... to the end of list t (this also modifies the original list);
t.copy() - produces a duplicate of the list t;
t.count(x) - tallies the number of occurrences of x in list t.

As an example, let's enhance the list from our last discussion by adding more details, such as the capital city and the total number of states:


              12345678910
            
# Initial and new lists
US_Info = ["USA", 9629091, 331002651]
US_Info_new = ["Washington D.C.", 50]

# Add new data using concatenation
print(US_Info + US_Info_new)

# Add new data using list method
US_Info.extend(US_Info_new)
print(US_Info)

Note

Keep in mind that the .extend() method needs an iterable object as its argument. In our case, we're using another list as the iterable.

An iterable object in Python is an object that can be iterated over, meaning you can traverse through all its elements in a sequence, such as a list, tuple, or string.

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Section 4. Chapter 2