Run update21, if you haven't already, to create the cs21/labs/02. Then cd into your cs21/labs/02 directory and create the python programs for lab 2 in this directory (handin21 looks for your lab 2 assignments in your cs21/labs/02 directory):
$ update21 $ cd cs21/labs/02 $ pwd /home/your_user_name/cs21/labs/02
Your programs are graded on both correctness and style. Please review
the comments regarding programming style on the main page.
Write a program, in a file named line.py, that asks the user to enter the value of two points in the Cartesian plane and then computes the slope of the line defined by those points and the distance between the points (formulas are on p.73, exercises 6 and 7).
Here is what two runs of your program might look like:
$ python line.py Given two points, (x1, y1) and (x2, y2), this program computes the distance between them and the slope of the line they define Enter the x coordinate of the first point: 1 Enter the y coordinate of the first point: 1 Enter the x coordinate of the second point: 4 Enter the y coordinate of the second point: 5 The distance between (1,1) and (4,5) is 5.00 The slope of the line they define is 1.33 $ python line.py Given two points, (x1, y1) and (x2, y2), this program computes the distance between them and the slope of the line they define Enter the x coordinate of the first point: 6 Enter the y coordinate of the first point: 12 Enter the x coordinate of the second point: 10 Enter the y coordinate of the second point: 30 The distance between (6,12) and (10,30) is 18.44 The slope of the line they define is 4.50To use math library function, remember to add this to the top of your program:
from math import *You could also try using print string formating to limit the number of places printed beyond the decimal point, but it is not necessary to do so.
Assuming that the current US population is 312 million, how much will it change in the future?
The US Census provides approximate rates of change:
Based on these numbers, write a program (in a file called pop.py) that prompts the user to enter a number of years, N. Your program should then output the current year's population and the approximate population for each of the next N years. Use tabular output (remember that "\t" is the tab character), and include some introductory text that explains what the program is doing, and it should clearly present the results. You may assume that every year is exactly 365 days (you do not have to account for leap year).
As an example, here is a run of my program when the user enters 2:
$ python pop.py This program displays the US population growth chart for the future Please enter the number of years into the future to display: 2 Year US Population ------------------------------ 2011 312000000 2012 314980325.275 2013 317960650.549Note: because of floating point round-off error, depending on how you structure your computation, your exact values could differ very slightly from mine beyond the decimal point, but it should be very slight, if at all.
$ python funstr.py Please Enter a string: abcdefg a ab abc abcd abcde abcdef abcdefg $ python funstr.py Please Enter a string: Hello-There H He Hel Hell Hello Hello- Hello-T Hello-Th Hello-The Hello-Ther Hello-There $ python funstr.py Please Enter a string: CS is awesome! C CS CS CS i CS is CS is CS is a CS is aw CS is awe CS is awes CS is aweso CS is awesom CS is awesome CS is awesome!Remember space is a character, you just can't always see it.
Copy your funstr.py file to a new file named funstrarrow.py:
% cp funstr.py funstrarrow.pyIn funstrarrow.py, add code to ouput the following pattern shown by the following example (like funstr.py, your solution should work for any string value entered by the user):
$ python funstrarrow.py Please Enter a string: hello there h he hel hell hello hello hello t hello th hello the hello ther hello there hello ther hello the hello th hello t hello hello hell hel he hnote how many times the full string "hello there" appears in the output.