CSci 284 - Exercise 1

Purpose: review of libraries for producing graphs from Python data, reading/writing common file formats for data, and working with large data sets.

Resources.

Today we're going to use the functions provided by the Matplotlib package. You'll receive a Visualizing Data activity to start working with this package. The examples also use a few functions from Numpy, an industrial-strength scientific computing package primarily written in the C programming language for speed. We'll be using a few of Numpy's math functions and arrays.

For further exploration later, this tutorial works for the version of Matplotlib installed on the lab computers.

Part 1

  1. Model 1 and Model 2 illustrate simple graphs using data produced by various math and random number functions. Enter and run both programs (simpleplot.py, histogram.py) before starting on the questions.

  2. The window that pyplot pops up to display graphs has a few buttons showing tools you can try out. Give a couple of these tools a try. Record on the back page of the activity what the tools you tried do. When done, just close the graph window to get your Python shell back.

  3.  Now work through the first two Models, answering the questions. Rerun each program as needed. Some questions might need hints:

    • Question 7: after doing this one, try changing call on line 6 to np.polyval([1, 0, -1], x) and see if it works similarly.
    • Question 8: this says "three Python libraries" because pyplot is a module inside the Matplotlib libray.
    • Question 10(b): the "width" asked for here is in terms of the values on the x-axis, not pixels
    • Question 11: give your best guess, don't spend much time haggling over possibilities

Demonstrate the correct output to the instructor.

Part 2

  1. Switch observer and driver. Move on to Model 3 in the Activity.
    • For the program on page 91, you'll need this file: data.csv
    • Open the file you just downloaded and make sure the data looks like the contents at the top of page 91
    • Enter and run the program and answer the questions on this page
    • Now modify the program to print row in the loop rather than row[1]. What is the type of row? It should be obvious from the output.
       
  2. Starting with Question 18 on page 82, you'll be writing a new program that deals with a much much larger data file
    • If you can't find the CSV file referenced in Question 18, try this one: scorecard.csv
    • Linux has a spreadsheet program called Calc, it should be near the top of your task bar---OR MAYBE NOT!
    • The different parts of Question 20 are intended to guide your thinking about how to write the program. Don't answer them on the page, but in your program.
    • Do answer Questions 21/22 on the page.
Demonstrate your final program to the instructor.