CS106 Lab 1: Getting started with Python, Linux, and Canopy. A. Using the interpreter as a fancy calculator

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1 CS106 Lab 1: Getting started with Python, Linux, and Canopy Dr. Victor Norman Goals: To learn How python can be used interactively for simple computational tasks. How to run Canopy Start playing with Turtle graphics. A. Using the interpreter as a fancy calculator Login to your machine. Your login id is your userid, e.g., vtn2 or eeg23. Your password is the same as your userid right now. Then, start Accessories LXTerminal. In this window, type yppasswd. Type in your userid (your old password) and choose a new password. Note that you will NOT see any characters as you type, but it is working. You do NOT have to choose a super-long password, but something different than your userid. Next, open up the Thunar File Manager (from the Desktop). Go to View Location Selector and select Toolbar Style. Close the File Manager. Next, start up Canopy by going to the menu, into Education Canopy. Now, you should see the Welcome to Canopy window. Click on the Editor button. In the resulting window, in the upper half you can open files to edit and run. In the lower half, you see a sub-window that reads Welcome to Canopy s interactive data-analysis environment! This is the window that shows you an interactive python session. You should see the python prompt: 1

2 In [1]: Try adding some values together. The interpreter prints out the result on the following line (when there is a result). In [1]: Out[1]: 2 In [2]: (3 + 4) ** 2 Out[2]: 49 In [3]: 2 ** 100 Out[3]: L Create some variables and put values in them: e.g., In [4]: a = 17 In [5]: b = 4444 Try some more stuff. Experiment! Be curious! Create some lists and play with them. You may have to use your book to figure this out (or google for python lists and you ll find all kinds of good stuff). Exercises: Create a new file in Canopy, in which you will record your answers to the following questions. Call it lab1_answers.txt. A.1. Use the python interpreter to find the number of seconds in a year. Record how you did it. A.2. Predict: if you create a variable var1 and put a value in it, then create variable var2 with a different value in it, and then do In [x]: var1 = var2 2

3 In [x]: var2 = var1 What values will be in var1 and var2 when you print them out. A.3. Create variables that hold the number of seconds in a minute, number minutes in an hour, number of hours in a day, and number of days in a year. Then, write a statement to compute the number of seconds in a year using these variables. Copy your code into your answer file for submission. B. Setting up your file system Find the Thunar File Manager icon in the bottom menu bar of your computer screen. Click on it. You can use this application to manage your file system. Let's start with some definitions: A directory is what Microsoft calls a Folder a place where you can store multiple files. Your benevolent professor will often refer to it as a directory, so you might as well get used to it. Your home directory is your top directory the top of the hierarchy where you can create sub-directories, store files, etc. It will have the name /home/<yourid>, e.g., /home/vtn2 or /home/eeg23. A submission directory has been created for each of you on a network file system located at /home/cs/106/current/<yourid>/. When you need to submit files and/or directories of files that need to be graded, you must copy those files over to your submission directory. You can use the Thunar file manager for most everything you will need to do. Use it now to create a directory called mycs106 in your home directory. You will do all your programming work in this directory for this class. I had you call it mycs106 so that you wouldn't confuse it with your submission directory in /home/cs/106/current/. Now, within mycs106, create a directory called lab1. C. Creating a program in Canopy Open a new Edit window in Canopy: File New Python file. 3

4 In the edit window, which probably says untitled-2 (or some such) at the top, type this: import turtle turtle.screen() t = turtle.turtle() t.circle(100) turtle.mainloop() Before you run the program, let's look at what it should do: The first line imports a package called turtle, which allows us to create all kinds of graphics elements circles, rectangles, etc. The next line creates a Screen, which we will draw on. The Screen() function is found in the turtle module, which is why we have to call turtle.screen() to use it. The next line creates a new Turtle object. Turtles can be moved around to draw stuff. The next line tells the turtle t to draw a circle with radius 100. The final line of the program calls the mainloop() which allows the user to interact with the Screen. If you forget this line, you can t close the window and go on with life Choose to save the file in a filename called lab1.py in your mycs106/lab1 directory. Run the program by choosing Run Run File, or clicking on the green right-facing arrow. Do you see the circle? Search in google for python turtle.circle. Investigate other ways you can call circle(). Try stuff out. 4

5 Alter the program in whatever way you want. Perhaps you want to add multiple circles, or you want to create multiple canvases. Maybe you want the circles to be different sizes. See if you can get some of them to be filled in. Play around a while and see what you can do. D. Submitting your files Using Thunar, go to /home/cs/106/current/<yourid> (with out the less-than and greater-than signs.) Create a folder/directory there called lab1. (Do not call it Lab1 or Lab 1 or lab 1 or ProfNormanHasCuteKnees. Call it lab1.) Then, copy your lab1.py file from your mycs106/lab1 directory to this submission directory in /home/cs/106/current/<yourid>/lab1. Also, submit the answers to the questions above by storing your answer file in the same directory: /home/cs/106/current/<yourid>/lab1/. It would be nice if the file was named lab1_answers.txt, but it really could be named anything. 5