Learn how to plot data with the matplotlib plotting library. Ditch Excel forever!
- practice reading data from a file
- practice using the matplotlib Python plotting library to analyze data and generate graphs
Mac OS X users only
If you do not already have a C compiler installed, you'll need one to install matplotlib. You have several options depending on your situation:
- Download and install Xcode (1.5 GB) from https://developer.apple.com/xcode/
- Download and install Command Line Tools for Xcode (175 MB) from https://developer.apple.com/downloads/index.action. This requires an Apple Developer account (free, but you have to sign up).
- Download and install kennethreitz's gcc installer (requires 10.6 or 10.7) from https://github.com/kennethreitz/osx-gcc-installer/
Please wave over a staff member and we'll help you pick which option is best for you computer.
Install the project dependencies
Please follow the official matplotlib installation instructions at http://matplotlib.sourceforge.net/users/installing.html
The dependencies vary across operating systems. http://matplotlib.sourceforge.net/users/installing.html#build-requirements summarizes what you'll need for your operating system.
A universal dependency is the NumPy scientific computing library. NumPy has download and installation instructions at http://numpy.scipy.org/
Installing matplotlib and its dependencies is somewhat involved; please ask for help if you get stuck or don't know where to start!
Download and un-archive the Jeopardy database project skeleton code
Un-archiving will produce a
JeopardyDatabase folder containing 3 Python files and one SQL database dump.
Create a SQLite database from the database dump
JeopardyDatabase is a file called
jeopardy.dump which contains a SQL database dump. We need to turn that database dump into a SQLite database.
Once you have SQLite installed, you can create a database from jeopardy.dump with:
sqlite3 jeopardy.db < jeopardy.dump
This creates a sqlite3 database called
Test your setup
At a command prompt, start
sqlite3 using the
jeopardy.db database by running:
That should start a sqlite prompt that looks like this:
SQLite version 3.6.12 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite>
At that sqlite prompt, type
.tables and hit enter. That should display a list of the tables in this database:
sqlite> .tables category clue sqlite>
From a command prompt, navigate to the
JeopardyDatabase directory and run
You should see a list of 10 jeopardy categories printed to the screen. If you don't, let a staff member know so you can debug this together.
Create a basic plot
python basic_plot.py. This will pop up a window with a dot plot of some data.
basic_plot.py. Read through the code in this file. The meat of the file is in one line:
pyplot.plot([0, 2, 4, 8, 16, 32], "o")
In this example, the first argument to
pyplot.plotis the list of y values, and the second argument describes how to plot the data. If two lists had been supplied,
pyplot.plotwould consider the first list to be the x values and the second list to be the y values.
- Change the plot to display lines between the data points by changing
pyplot.plot([0, 2, 4, 8, 16, 32], "o")
pyplot.plot([0, 2, 4, 8, 16, 32], "o-")
Add x-values to the data by changing
pyplot.plot([0, 2, 4, 8, 16, 32], "o-")to
x_values = [3, 4, 7, 20, 22, 25] y_values = [0, 2, 4, 8, 16, 32] pyplot.plot(x_values, y_values, "o-")
Note how matplotlib automatically resizes the graph to fit all of the points in the figure for you.
Read these short documents:
- Pyplot tutorial (just this one section; stop before the next section "Controlling line properties"): http://matplotlib.sourceforge.net/users/pyplot_tutorial.html#pyplot-tutorial
- List of line options, including line style, shapes and colors: http://www.thetechrepo.com/main-articles/469-how-to-change-line-properties-in-matplotlib-python
Check your understanding:
- What does matplotlib pick as the x values if you don't supply them yourself?
- What options would you pass to
pyplot.plotto generate a plot with red triangles and dotted lines?
2. Query the database with SELECT
Try running the following queries from the sqlite prompt:
- SELECT * FROM category;
- SELECT NAME FROM category;
- SELECT * FROM clue;
- SELECT text, answer, value FROM clue;
- SELECT text, answer, value FROM clue LIMIT 10;
clue tables with your own SELECT queries.
Check your understanding:
- What does
*mean in the above queries?
- What does the
LIMITSQL keyword do?
- Does case matter when making SQL queries?
Step 2 resources:
- Using SELECT: http://www.w3schools.com/sql/sql_select.asp
3. Make database queries from Python
Examine the code in
jeopardy_categories.py. To make a database query from Python, you need to:
- Import a Python library for making database connections
- Establish a connection to the desired database
- Get a cursor from the database for making queries
- Execute the database query using the standard SQL syntax
- Retrieve the list of results from the database cursor
- Do something useful with the results, like print them
- Close the database connection
Match up each of these steps with lines of code in the file.
4. Tweak the existing Jeopardy scripts
jeopardy_categories.py to print both the category and game number
tip: Remind yourself of the
categories schema by running
.schema category at a sqlite prompt.
Example categories: DETECTIVE FICTION (game #1) THE OLD TESTAMENT (game #2) ASIAN HISTORY (game #4) RIVER SOURCES (game #5) WORLD RELIGION (game #3) SEAN SONG (game #2) ANIMATED MOVIES (game #1) NEW YORK CITY (game #6) AFRICAN WILDLIFE (game #7) LITTLE RED RIDING HOOD (game #8)
jeopardy_clues.py to only print clues with an $800 value.
A good way to achieve this is by adding a
WHERE clause to the SQL query in
WHERE clauses in this short document:
- The WHERE Clause: http://www.w3schools.com/sql/sql_where.asp
Example clues: [$800] A: She also created the detectives Tuppence & Tommy Beresford Q: What is 'Agatha Christie' [$800] A: According to this Old Testament book, this "swords into plowshares" prophet walked naked for 3 years Q: What is 'Isaiah' ...
5. Daily Doubles
Write a script that prints 10 daily doubles and their responses.
clue table has an
Category: NEW YORK CITY Question: The heart of Little Italy is this street also found in a Dr. Seuss book title Answer: Mulberry Street === Category: RIVER SOURCES Question: This Mideastern boundary river rises on the slopes of Mount Hermon Answer: the Jordan === Category: ROOM Question: The Titanic has 3 rooms for this--only men were allowed there, as women weren't supposed to do it in public Answer: smoking ...
1. Random category clues
Write a script that randomly chooses a category and prints clues from that category.
tip: SQL supports an "
ORDER BY RANDOM()" clause that will return rows in a random order. For example, to randomly pick 1 category id you could use:
SELECT id FROM category ORDER BY RANDOM() LIMIT 1
You can also use
ORDER BY to sort the clues by value.
5 GUYS NAMED MOE [$200] Last name of Moe of the Three Stooges [$400] Moe Strauss founded this auto parts chain along with Manny Rosenfield & Jack Jackson [$600] Major league catcher Moe Berg was also a WWII spy for this agency, precursor of the CIA [$800] Term for the type of country music Moe Bandy plays, the clubs where he began, or the "Queen" he sang of in 1981 [$1000] This "Kool" rapper's album "How Ya Like Me Now" began a rivalry with LL Cool J
- Using ORDER BY: http://www.w3schools.com/sql/sql_orderby.asp
2. Random game categories
Write a script to randomly choose a game number and print the categories from that game.
category table has
round fields. round 0 is the Jeopardy round, round 1 is the Double Jeopardy round, and round 2 is Final Jeopardy.
Categories for game #136: 0 WELCOME TO MY COUNTRY 0 METALS 0 GO GO GAUGUIN 0 FILE UNDER "M" 0 ANIMATED CATS 0 MAO MAO MAO MAO 1 SHAKESPEARE'S OPENING LINES 1 HEY, MARIO! 1 BRIDGE ON THE RIVER.... 1 RUNNING MATES 1 13-LETTER WORDS 1 TONY BENNETT'S SONGBOOK 2 IN THE NEWS 2000
3. Top 20 Jeopardy categories
Read about the
GROUP BY clause and write a script using it to print the 20 most common Jeopardy categories.
An example of using
GROUP BY and
ORDER BY to produce an ordered list of counts on a hypothetical
foo field is:
SELECT foo, COUNT(foo) AS count FROM my_table GROUP BY foo ORDER BY count
81 LITERATURE 79 BEFORE & AFTER 73 WORD ORIGINS 71 SCIENCE 64 BUSINESS & INDUSTRY 63 AMERICAN HISTORY ...
You've learned about SQL and making database queries from within Python. Keep practicing!