Prelab 5 Due: Beginning of lab on 2020-03-13

Review lists

Review the class notes and examples from this week covering lists. In particular, recall there are built-in functions that apply to lists:

• len(L) Returns the number of items in list L
• max(L) Returns the maximum value in list L
• min(L) Returns the minimum value in list L
• sum(L) Returns the sum of the values in list L
• sorted(L) Returns a copy of list L where the items are in order from smallest to largest (this does not mutate L.)

Furthermore, the Python documentation for lists includes links to operations and methods that apply to common sequence types and mutable sequence types including lists.

Practice with built-in functions and methods on lists

Answer these two questions on Gradescope.

Question 1: Write a Python expression that sorts a list data in place. For example, if data were the list [45, 6.2, -3.5, 10] then after execution of your expression the list data would contain [-3.5, 6.2, 10, 45].

Question 2: Write a sequence of Python statements that given a non-empty list would return the middle value in the list. For an odd number of data elements, this is the value in position len(list) // 2. For an even number of data elements, return the average of the two middle items. For example, if data were the list [35, 14, 10, 81, 40] then middle(data) would evaluate to 10. If data were the list [35, 14, 10, 81] then middle(data) would evaluate to 12, the average of 14 and 10. Your statements would complete the following code if pasted in:

def middle(sequence):
    """
    Returns middle value in non-empty sequence
    
    Args:
        sequence: a sequence of values of any type, sorted or unsorted
        
    Returns:
        the middle element if sequence has odd length, or the average
        of the two middle elements if sequence has even length
    """

Prepare for Lab

Review the lab assignment carefully before lab so you are ready to go. You will work during lab with a partner using a technique called Pair Programming.