Lab 6, CSC 101

This lab provides additional exercises on iteration over lists.

Download, place it in your cpe101 directory, and unzip the file.

Fold Pattern

Develop these functions in the fold directory in files and

Each of the functions for this part of the lab is to be implemented using the fold pattern. In this pattern, the values in the input list are combined in some manner (e.g., an arithmetic or relational operation) to compute a single result value. Each of these functions will use a local variable (or local variables) to hold the computed value as the list is traversed. This variable is often updated at each step of the iteration.


The sum function returns the sum of all values in the input list.


The index_of_smallest function returns the index of the smallest value in the input list. If the list is empty (i.e., the length is ≤ 0), then the function returns -1.


The nearest_origin function returns the index of the point nearest the origin. If the list is empty, then the function returns -1.


For this part of the lab you will develop a function that will be of use in the last assignment of the quarter. In, define the following function.


The groups_of_3 function takes a list of values as its only argument. This function will group the elements of the input list into groups of three (i.e., the first three consecutive values form a group, the second three form a group, etc.). This function must return a list of lists where each sublist (excluding, perhaps, the last) is a group of three values. If there are not enough values to fill the last grouping, then it will contain fewer than three values.

As examples, consider the following.

>>> groups_of_3([1,2,3,4,5,6,7,8,9])
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]
>>> groups_of_3([1,2,3,4,5,6,7,8])
[[1, 2, 3], [4, 5, 6], [7, 8]]


The while statement is another way to specify iteration, though it is typically used for a different type of iteration than that over lists.

For this part of the lab, edit the file in the loops directory. Complete the while_version function by translating the for statement from the for_version function into an equivalent while statement. Think carefully about the different steps in the for statement.


Demonstrate the test cases from each part of the lab to your instructor to have this lab recorded as completed. In addition, be prepared to show the source code to your instructor.


The handin command will vary by section.