McNulty // w7d2

Winter 2015

Planned schedule and activities

9:00 am: Testing Irmak's voice.....Nope, still not working.

9:15 am: Introduction to Fletcher. Hold on to your seat, Dorothy, 'cause Kansas is going bye-bye.

9:30 am: More on databases: The concept of NoSQL databases and MongoDB

10:15 am: MongoDB Challenges

12:00 pm: The dreaded lunchtime. Stay warm.

1:30 pm: Back for glorious work on Mongo challenges and Fletcher data gathering

3:00 pm: workshop with Brooke Parsons from

5:00 pm: The End


Intro to Mongo
Mongo query documentation
Pymongo tutorial

Lecture Notes

NoSQL and MongoDB slides (198.3 KB)

Mongo / Pymongo Challenges


Make sure that mongodb is setup and the database server (mongod) is running.

We are going to work with reviews of Heavy Metal movies. Hellz Yeah. Unzip and unpickle the following file: (1.1 MB)

import pickle
with open("heavy_metal_parsed.pkl", 'r') as datafile:
    heavy_metal_reviews = pickle.load(datafile)

It's a list of dictionaries. One dictionary per review: perfect for a mongo document. The key raw has the full text as a list of lines. For example, to see the first review, you can do:

first_review = heavy_metal_reviews[0]
for line in first_review['raw']:
    print line

which will give you:

200 MOTELS (1971)
DIRECTORS: Tony Palmer, Frank Zappa
CAST: Frank Zappa, Ringo Starr, Mark Volman, Howard Kaylan, Keith Moon
Frank Zappa
Nun Desecration
Beyond his metal sainthood for battling the censor-witches of the PMRC and getting named checked by Deep Purple in “Smoke on the Water”, musical visionary Frank Zappa led many rock fans to heavy metal.
And, from there, he led many metal fans to the outer expanses of rock’s possibilities.
Zappa also opened countless banging heads to the far reaches of jazz, classical, doo-wop, and any other art form that could involve (brilliant) noise and (brilliantly dumb) dirty jokes.
200 Motels is Zappa’s first crack at major motion picture madness, and it
embodies the much forgotten cultural moment when acid rock tumbled forever into the black pits of rising heavy metal.
Surrealistic sketches and psychedelic set pieces about the insanity of a being on tour are interspersed among performances in which the Mothers jam with London Philharmonic.
Ringo Starr plays Zappa during the talking parts. Zappa himself, plays guitar throughout, demonstrating how very much of a six-string maestro he was, every lick on par with his future collaborators Steve Vail and Yngwie Malmsteen.
- A psychedelic cartoon interlude admiringly tweaks Black Sabbath and Grand Funk Railroad.
- Keith Moon, madman drummer of the Who, pops up—and off—as “The Hot Nun.”

Let's see what other fields each document has:

print first_review.keys()



Basically, each section in the review is parsed into it's own key.

Ok, put these documents into a mongodb collection. For these challenges, do not use the heavy_metal_reviews list directly. Use mongo queries (you can use the mongo client directly or use pymongo from within python).

Challenge 1

Make a histogram of the years in the data. How many metal movies came out over the years?

Challenge 2

Find the cast member that appeared in most Heavy Metal movies. Is there one that is shared by more than one of these movies? Or are they all completely different actors for every movie?

Challenge 3

Find the most used words in Heavy Metal film titles. Is there a word that appears in a lot of them? Is it "The"? If it is something like "the", How can you get around that? Find one "meaningful" word that appears the most (this means non-structural word, unlike "the" or "a" or "in")

Challenge 4

METAL CRED section lists themes included in these movies that makes them more metal. What were the top 5 metal cred keywords in the 70s? In 80s? In 90s, In 2000s?

Challenge 5

Let's use the length of the METAL CRED section as a proxy score for how metal a movie is. Let's call this the METAL SCORE. To each mongo document, add the metal_score as a new field.

Challenge 6

Find the director that is MOST METAL per movie (director with the highest average metal score). Remember that some movies have multiple directors.

Challenge 7

The majority of directors and actors will have worked on a single movie. See if there are any directors that worked with an actor more than once. If so, find the director-actor duo that have worked together the most times.

Challenge 8

Create an index on the 'director' field to make the queries involving it faster.
What is an index?

Creating an index in mongo
Creating an index in pymongo
Single field index on mongo
Mongo documentation on indexes

Challenge 9 (Optional challenge for early finishers)

For each decade, make a histogram of metal scores. Also, calculate the average metal score for each decade. Which decade was the most pure metal decade?

Note (rather than a challenge)

In the latest version of mongo, you can do a text query. To do this, you need to create one (only one) text-based index. Let's index the_meat field so we can make text search queries on it (in pymongo):[("the_meat", pymongo.TEXT,)])

Now you can do text search. For example, let's search for the phrase "hitting power chords" within "the_meat" fields of all our documents.{"$text": {"$search": "hitting power


It has found 206 reviews. I can print the titles of the first 10 reviews that were returned in this text search:

ten_matches = r.find({"$text": {"$search": "hitting power chords"}}).limit(10)
for match in ten_matches:
    print match["title"]


Enjoy your text searches : ) These can be very useful in some apps.