rough 07-reduce created

Author: ShMcK

tutorial/1/07/01-reduce.spec.js

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+"use strict";
+var chai = require('chai');
+var expect = chai.expect;
+var spies = require('chai-spies');
+chai.use(spies);
+var path = require('path');
+var loadJS = require('../../common/loadJS').default;
+
+describe('var total', function() {
+
+  it('should call reduce', function() {
+    var spy = chai.spy.on(Array, 'reduce');
+    loadJS('07-reduce.js');
+    expect(spy).to.have.been.called();
+  });
+
+  it('should add the numbers up', function () {
+    expect(total).to.equal(54);
+  });
+
+});

tutorial/1/07/02-reduce.spec.js

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+"use strict";
+var chai = require('chai');
+var expect = chai.expect;
+var spies = require('chai-spies');
+chai.use(spies);
+var path = require('path');
+var loadJS = require('../../common/loadJS').default;
+
+loadJS('07-reduce.js');
+
+describe('var averages', function() {
+
+  it('should calculate the average of each class', function () {
+    let averages = data.map(function(course) {
+      var sum = course.students.reduce(function(total, student) {
+        total += student.score;
+        return total;
+      }, 0);
+      return Math.round(sum / course.students.length, 0);
+    });
+    expect(averages).to.deep.equal([57, 67, 70, 70, 71, 62, 67, 73, 62, 57]);
+  });
+});

tutorial/1/07/03-reduce.spec.js

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+"use strict";
+var chai = require('chai');
+var expect = chai.expect;
+var spies = require('chai-spies');
+chai.use(spies);
+var path = require('path');
+var loadJS = require('../../common/loadJS').default;
+
+loadJS('07-reduce.js');
+
+describe('var suspectScores', function() {
+
+  it('should reduce to an array of suspect scores', function() {
+
+    // var suspects = ['Hack Kerr', 'Kevin Mitnick', 'Albert Gonzalez'];
+    // var suspectData = data.map(function(course) {
+    //     return course.students.filter(function(student) {
+    //       return suspects.indexOf(student.name) > -1;
+    //     });
+    //   }).concatAll()
+    //   .reduce(function(prev, curr) {
+    //     let index = prev.findIndex(function(item) {
+    //       return item.name === curr.name;
+    //     });
+    //     if (index < 0) {
+    //       prev.push({
+    //         name: curr.name,
+    //         scores: [].concat(curr.score)
+    //       });
+    //     } else {
+    //       prev[index].scores.push(curr.score);
+    //     }
+    //     return prev;
+    //   }, []);
+
+
+    expect(suspectScores).to.deep.equal([{
+      name: 'Albert Gonzalez',
+      scores: [35, 37, 73, 74, 94, 67, 39, 70, 56, 52]
+    }, {
+      name: 'Hack Kerr',
+      scores: [85, 86, 92, 75, 83, 96, 94, 87, 89, 102]
+    }, {
+      name: 'Kevin Mitnick',
+      scores: [72, 52, 47, 89, 47, 75, 81, 41, 40, 37]
+    }]);
+  });
+
+});

tutorial/1/07/04-reduce.spec.js

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+"use strict";
+var chai = require('chai');
+var expect = chai.expect;
+var spies = require('chai-spies');
+chai.use(spies);
+var path = require('path');
+var loadJS = require('../../common/loadJS').default;
+
+loadJS('07-reduce.js');
+
+describe('var suspectScores', function() {
+
+  it('should map over suspect data to find the score differences', function() {
+    var suspectData = [{
+      name: 'Albert Gonzalez',
+      scores: [35, 37, 73, 74, 94, 67, 39, 70, 56, 52]
+    }, {
+      name: 'Hack Kerr',
+      scores: [85, 86, 92, 75, 83, 96, 94, 87, 89, 102]
+    }, {
+      name: 'Kevin Mitnick',
+      scores: [72, 52, 47, 89, 47, 75, 81, 41, 40, 37]
+    }];
+    var averages = [57, 67, 70, 70, 71, 62, 67, 73, 62, 57];
+
+    var change = suspectData.map(function(suspect) {
+      return {
+        name: suspect.name,
+        scores: suspect.scores,
+        change: suspect.scores.reduce(function(a, b, index) {
+          a += b - averages[index];
+          return a;
+        }, 0)
+      };
+    });
+    expect(change).to.deep.equal([{
+      name: 'Albert Gonzalez',
+      scores: [35, 37, 73, 74, 94, 67, 39, 70, 56, 52],
+      change: -59
+    }, {
+      name: 'Hack Kerr',
+      scores: [85, 86, 92, 75, 83, 96, 94, 87, 89, 102],
+      change: 233
+    }, {
+      name: 'Kevin Mitnick',
+      scores: [72, 52, 47, 89, 47, 75, 81, 41, 40, 37],
+      change: -75
+    }]);
+  });
+
+});

tutorial/1/07/05-reduce.spec.js

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+"use strict";
+var chai = require('chai');
+var expect = chai.expect;
+var spies = require('chai-spies');
+chai.use(spies);
+var path = require('path');
+var loadJS = require('../../common/loadJS').default;
+
+loadJS('07-reduce.js');
+
+describe('var likelySuspect', function() {
+
+  it('should reduce down to a suspect name', function () {
+    expect(likelySuspect).to.equal('Hack Kerr');
+  });
+});

tutorial/1/07/reduce.md

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 ### reduce
 Array -> transform into anything
 
+```js
+function add(prev, curr) {
+    console.log(`add(${prev}, ${curr}) -> ${prev + curr}`)
+    return prev + curr;
+}
 
+[1, 5, 10].reduce(add, 100); // initial value
 
-+ Use `reduce` to calculate the class average
+// add(100, 1) -> 101
+// add(101, 5) -> 106
+// add(106, 10) -> 116
+//> 116
+```
+
+
+
++ Use `reduce` to sum the numbers in the `practice` array
 @test('1/07/01-reduce')
 @action(open('07-reduce.js'))
+@action(set(
+```
+var practice = [1, 1, 2, 3, 5, 8, 13, 21];
 
-+ `reduce` to suspect scores
+// total the numbers using a reduce function
+// hint: start at 0
+var total = practice.reduce();
+```
+))
+
++ `map` over each course and use `reduce` to calculate the class averages for each class. Set `averages` to the resulting array of all class averages.
 @test('1/07/02-reduce')
+@action(insert(
+```
+// Remember, an average is the sum of all student scores divided by the number of students
+// set the result to an array, for example: [50, 65, 75, 85, ...];
+var averages = courses.reduce();
+```
+))
 
-+ `map` over suspect data to find the score differences
++ `reduce` to an array of suspect scores
 @test('1/07/03-reduce')
+@action(insert(
+```
+
+// [{ name: 'suspectName', scores: [ 50, 65, 75, 85...] }, ... ]
+var suspectScores = courses.reduce();
+```
+))
 
-+ `reduce` down to likely suspect names
++ `map` over suspect data to find the `"difference"` from subtracting the students score from the average score. Add this to `suspectScores` using the key `difference`. The resulting array should look like this:
+```js
+[{
+  name: 'suspectName',
+  scores: [50, 65, 75, 85...],
+  difference: 15
+}]
+```
 @test('1/07/04-reduce')
+
+
++ `reduce` down to any likely suspect names by filtering with the `isCheater` function
+@test('1/07/05-reduce')
+@action(insert(
+```
+
+function isCheater(suspect) {
+  return suspect.difference > 200;
+}
+
+// reduce down to a string of likely suspects
+var likelySuspect = suspectScores.reduce().join(', ');
+console.log(likelySuspect);
+```
+))