This lab provides additional exercises on iteration over lists.
Download lab6.zip, place it in your cpe101
directory, and unzip the file.
Develop these functions in the fold directory in files
fold.py and fold_tests.py.
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 groups.py,
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 loops.py 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.
Those in Aaron Keen's sections will not submit the lab.