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HOMEWORK: HOMEWORK 5.4 Removing Rural Residents In this problem you will calculate the number of people who live in a zip code in the US where the city starts with a digit. We will take that to mean they don't really live in a city. Once again, you will be using the zip code collection, which you will find in the 'handouts' link in this page. Import it into your mongod using the following command from the command line: > mongoimport -d test -c zips --drop zips.json If you imported it correctly, you can go to the  test  database in the mongo shell and conform that > db.zips.count() yields 29,467 documents. The project operator can extract the first digit from any field. For example, to extract the first digit from the city field, you could write this query: db.zips.aggregate([ {$project: { first_char: {$substr : ["$city",0,1]}, } } ]) Using the aggregation framework, calculate the sum total of people who are living in a z...

HOMEWORK: HOMEWORK 5.3 (HANDS ON) Who's the easiest grader on campus? A set of grades are loaded into the  grades  collection.  The documents look like this: { "_id" : ObjectId("50b59cd75bed76f46522c392"), "student_id" : 10, "class_id" : 5, "scores" : [ { "type" : "exam", "score" : 69.17634380939022 }, { "type" : "quiz", "score" : 61.20182926719762 }, { "type" : "homework", "score" : 73.3293624199466 }, { "type" : "homework", "score" : 15.206314042622903 }, { "type" : "homework", "score" : 36.75297723087603 }, { "type" : "homework", "score" : 64.42913107330241 } ] } There are documents for each student (student_id) across a variety of classes (class_id). Note that not all students in the ...

HOMEWORK: HOMEWORK 5.2 (HANDS ON) Crunching the Zipcode dataset Please calculate the average population of cities in California (abbreviation CA) and New York (NY) (taken together) with populations over 25,000. For this problem, assume that a city name that appears in more than one state represents two separate cities. Please round the answer to a whole number. Hint: The answer for CT and NJ (using this data set) is 38177. Please note: Different states might have the same city name. A city might have multiple zip codes. For purposes of keeping the  Hands On  shell quick, we have used a subset of the data you previously used in zips.json, not the full set. This is why there are only 200 documents (and 200 zip codes), and all of them are in New York, Connecticut, New Jersey, and California. If you prefer, you may download the handout and perform your analysis on your machine with > mongoimport -d test -c zips --drop small_zips.json Once you've genera...

HOMEWORK: HOMEWORK 5.1 (HANDS ON) Finding the most frequent author of comments on your blog In this assignment you will use the aggregation framework to find the most frequent author of comments on your blog. We will be using the same basic dataset as last week, with posts and comments shortened considerably, and with many fewer documents in the collection in order to streamline the operations of the  Hands On  web shell.  Use the aggregation framework in the web shell to calculate the author with the greatest number of comments.  To help you verify your work before submitting, the author with the fewest comments is Cody Strouth and he commented 68 times.  Once you've found the correct answer with your query, please choose your answer below for the most prolific comment author.  Note: this data set is relatively large. Due to some quirks of the shell, the entire result set gets pulled into the browser on find(), so if you want to see the document s...