Lists in Python

1. Lists in Python Creating lists

2. Simple ways to create a list • Hard code the values mylist = [3, 9, ‘a’, 7.2] • Using the replication operator • mylist = [0] * 100 (gives a list with 100 zeros) • Use the split method on a string • Use the readlines method on a file • Put [] around a variable if my_num is 5, then [ my_num] is the list [5]

3. Append vs. Concatenate • Both can be used to add to an existing list but their syntax is not the same • The concatenate operator + uses two lists and creates a bigger one • You cannot say mylist = mylist + “joe”, it must be mylist = mylist + [“joe”] • Append is a method which adds an element to the right end of a list – any type of data • mylist.append(“3”) makes mylist one element longer

4. List accumulation • Either concatenation or append can be used with lists as accumulators • Initialize the list variable as an empty list [] • inside your loop either concatenate or append the new item onto your list variable