Description
We have used several built-in modules or libraries like math, turtle, and sys. In this lab you will
build several user-defined modules or libraries. A module or library allows you to logically organize
your Python code. Grouping related code into a module makes the code easier to understand and use.
In its simplest form, a module is a file consisting of Python code. A module can define functions,
variables, and classes (we will look at classes in the last third of CS8). A module can also include
runnable code!
Part A
Create a module named cone.py. Define three functions with arguments r (radius) and h (height):
volume(r, h), surface_area(r, h), and printstats(r, h) to calculate the volume and surface area of a cone
with radius r and height h. printstats(r, h) displays to two decimal places both the volume and
surface_area. Don’t forget to document each function by describing its purpose (this is used by
Python’s help() function to display information about a function). For example to document the
volume() function do as follows,
def volume(r, h):
”’
volume(r,h) computes the volume of a right-circular cone with radius r and height h.
”’
…
Now test the cone module as illustrated in the Python Shell. Note what gets
displayed when help(volume) is called.
Part B
Create a module named specialsums.py. Define three functions with one argument n, an integer:
gauss(n), sumofsqs(n), and sumofcubes(n). Note that the caller provides the value for n.
gauss(n) computes the sum:
1 + 2 + 3 + … + n
sumofsqs(n) computes:
1 + 22 + 32 + … + n2
sumofcubes(n) computes:
1 + 23 + 33 + … + n3
Make sure your functions work properly, that is, returns 0 when n is 0 or a negative integer. Now
test the specialsums module as illustrated in the Python Shell.
By placing a description at the beginning of this module (use ‘ ‘ ‘ document here ‘ ‘ ‘) anyone using it
can ask for help(specialsums) to display each function and their description.
Exercise: Implement the fourth function sumconsecutive(m,n) described above.
The dir( ) Function
The dir() built-in function returns a sorted list of strings containing the names defined by a module.
The list contains the names of all the modules, variables and functions that are defined in the
specified module. Here is an example for you to run.
Here is the output produced:
Timing Code in Python
In computer science, one way to test the efficiency of a function or program segment is to time the
execution of the function call or program segment on different argument values and/or on different
sets of data.
The time() function returns the time (in seconds) from January 1, 1970 (This is when time began,
because the Unix operating system was created then). Here is an outline of how function calls and
program segments are timed.
import time
start = time.time()
### code to be timed goes here (place function call here)
stop = time.time()
print(‘%1.2f seconds’ % (stop – start))
Part C
Two ways to compute the cube of a number u is to use the exponentiation operator to form u**3 or to
use repeated multiplication to form u*u*u. Time the function sumofcubes(N) using these two ways of
calculating a cube of a number, for the following values of N.
sumofcubes(N) with u**3 sumofcubes(N) with u*u*u
|———-|————| |———-|————|
| N | Time (sec) | | N | Time (sec) |
|———-|————| |———-|————|
|5000000 | | |5000000 | |
|———-|————| |———-|————|
|10000000 | | |10000000 | |
|———-|————| |———-|————|
|15000000 | | |15000000 | |
|———-|————| |———-|————|
|20000000 | | |20000000 | |
|———-|————| |———-|————|
|25000000 | | |25000000 | |
|———-|————| |———-|————|
