bob-ross

Teaching the Joy of Clojure with the Joy of Painting.

Prerequisites

Have the clojure CLI tools installed and running on your local machine.

Lesson

In src/bob_ross/core.clj, you will find a bunch of function definitions that currently have no body. To complete this lesson, you will need to write the code that solves the problem in each functions docstring. Once you've finished each section, you can check your answers by running the related test case.

For each problem, you can use the episodes definition to access the CSV data in resources/episodes.csv. This refers to a vector of maps, where each map looks like:

{:CACTUS             "0"
 :RIVER              "1"
 :BARN               "0"
 :BOAT               "0"
 :MOUNTAINS          "0"
 :CIRRUS             "0"
 :CONIFER            "0"
 :HALF_OVAL_FRAME    "0"
 :TRIPLE_FRAME       "0"
 :DECIDUOUS          "1"
 :LAKES              "0"
 :FLOWERS            "0"
 :AURORA_BOREALIS    "0"
 :FIRE               "0"
 :PATH               "0"
 :FARM               "0"
 :TOMB_FRAME         "0"
 :FLORIDA_FRAME      "0"
 :BEACH              "0"
 :SNOWY_MOUNTAIN     "0"
 :PERSON             "0"
 :MILL               "0"
 :PORTRAIT           "0"
 :NIGHT              "0"
 :STEVE_ROSS         "0"
 :OVAL_FRAME         "0"
 :DOCK               "0"
 :ROCKS              "0"
 :BRIDGE             "0"
 :MOON               "0"
 :FOG                "0"
 :LAKE               "0"
 :CUMULUS            "0"
 :APPLE_FRAME        "0"
 :WATERFALL          "0"
 :CLOUDS             "0"
 :SUN                "0"
 :TREE               "1"
 :WINTER             "0"
 :GUEST              "0"
 :CLIFF              "0"
 :WINDOW_FRAME       "0"
 :CABIN              "0"
 :EPISODE            "S01E01"
 :TREES              "1"
 :SNOW               "0"
 :WINDMILL           "0"
 :GRASS              "1"
 :BUSHES             "1"
 :PALM_TREES         "0"
 :MOUNTAIN           "0"
 :SPLIT_FRAME        "0"
 :BUILDING           "0"
 :SEASHELL_FRAME     "0"
 :HILLS              "0"
 :WAVES              "0"
 :FRAMED             "0"
 :TITLE              "A WALK IN THE WOODS"
 :STRUCTURE          "0"
 :CIRCLE_FRAME       "0"
 :OCEAN              "0"
 :RECTANGULAR_FRAME  "0"
 :LIGHTHOUSE         "0"
 :DIANE_ANDRE        "0"
 :FENCE              "0"
 :DOUBLE_OVAL_FRAME  "0"
 :RECTANGLE_3D_FRAME "0"
 :HALF_CIRCLE_FRAME  "0"
 :WOOD_FRAMED        "0"}

Where "0"/"1" is the binary representation if an object was painted or not.

Questions

First Episode Title

Using the episodes data, determine what the title of the first episode of The Joy of Painting. Remember, the episodes reference is a faithful copy of the CSV, so order is preserved. Once you've filled in the function, run this command to check your answer from the command line:

clj -M:test -i :first

Boat Episode Detection

Given the map representing an episode, determine if the episode featured a boat or not and return the appropriate boolean. Once you've filled in the function, run this command to check your answer from the command line:

clj -M:test -i :second

Steve Ross Episode Count

Find the integer count of the number of episodes that featured Bob's son, Steve Ross. Remember, there are a lot of ways of tackling the same problem. Often times, it's easier to get code that works and than optimize it after the fact. Once you've filled in the function, run this command to check your answer from the command line:

clj -M:test -i :third

As an additional challenge, write this function so it only has to iterate over a collection one time.

Finding Episodes by Subject

Find the episodes identifiers S01E01 for every episode that contains the object referred to by the supplied keyword, e.g. :TREE. Remember, if you are solving common problems between functions, it's often a good idea to create new functions with defn so you can reuse your code.

Once you've filled in the function, run this command to check your answer from the command line:

clj -M:test -i :fourth

As an additional challenge, update this function to accept either a keyword or a case-insensitive string. To test your solution to the challenge, run this command:

clj -M:test -i :fourth-challenge

Finding Subjects By Episode

Given two integers representing the season number and the episode number, find the list of things painted in that episode. If the numbers refer to an episode that doesn't exist, return the keyword :not-found. Here are a few things to remember:

• All episodes are identified by their :EPISODE, which is always of the form: S, followed by exactly 2 integers representing the season, and then E followed by exactly 2 integers representing the episode number.
• The episode title is never painted on an original Bob Ross painting, so you may have to remove data from any episodes you find.

clj -M:test -i :fifth

Additional Challenges

Once you've completed the above, take note of src/bob_ross/server. This defines a simple HTTP server with exactly 2 endpoints.

GET "/v1/episodes/subject/:subject"
GET "/v1/episodes/season/:season/episode/:episode"

These endpoints will pull the data off of any incoming URIs, and pass them to the functions you wrote to solve the fourth and fifth questions respectively.

To test them, you can start the webserver with the following command:

clojure -M -m bob-ross.server

Then, you can use curl or Postman to send requests to localhost:8080 to receive responses.

Once you have this up and working, make these updates to your code:

• Return a status 404 whenever the subject, season, or episode is invalid.
• Serve a route v1/episodes/subjects that responds with a list of every subject of a painting that's appeared on The Joy of Painting.
• Update ross/find-subjects-by-episode to build a lookup map so it doesn't have to search through every episodes on every call.

Helpful Functions

There is great documentation with examples of the clojure programming language online. The following is a list of clojure functions that may help you solve these challenges:

• first
• keys
• vals
• filter
• count
• map
• str
• keyword
• clojure.string/upper-case
• dissoc
• reduce
• reduce-kv
• conj
• if
• when
• zipmap