Grading

You work for a school, and you need to help the teachers come up with some analytics about their students.

Challenge 1 - Determining differences

You are given an array of grades. You need to process this array, and return an array that describes whether each grade was higher, lower or even to the previous grade.

So given the following array:

[6,3,5,4,3,4,4,5]

Your code would produce:

[:down,:up,:down,:down,:up,:even,:up]

When given an empty array, it returns an empty array.

NOTE: your array tracks the differences between grades, so it will be one item shorter than the given array.

Challenge 2 - Finding students in decline

A student is considered in decline if they have 3 grades lower than previous grades, even if there are some steady grades in there. For example:

[10, 10, 10, 9, 9, 8, 8, 8, 8, 7] # => [:even, :even, :down, :even, :down, :even, :even, :even, :down]
[10, 10, 10, 9, 9, 8, 8, 8, 8, 7] # => in decline

[10, 9, 8, 7] # => [:down, :down, :down]
[10, 9, 8, 7] # => in decline

[10, 9, 8, 7, 8] # => [:down, :down, :down, :up]
[10, 9, 8, 7, 8] # => not in decline

[10, 9, 8] # => [:down, :down]
[10, 9, 8] # => not in decline

Challenge 3 - Check your code

There are 27 students in decline in the data/grades.json files, and 73 students not in decline.

Run you code against this dataset, and make sure that the results match.

Setup

Fork
Clone
Turn on TravisCI for the fork by visiting https://travis-ci.org/profile/, clicking the "Sync now" button and scrolling down to find the repository to build.
Create a new branch for your work using git checkout -b v1
Implement specs and code
Push using git push -u origin v1

Further Practice

This warmup can be completed multiple times to increase your comfort level with the material. To work on this from scratch, you can:

Add an upstream remote that points to the original repo git remote add upstream git@github.com:gSchool/THIS-REPO.git
Fetch the latest from the upstream remote using git fetch upstream
Create a new branch from the master branch of the upstream remote git checkout -b v2 upstream/master
Implement specs and code
Push using git push -u origin v2