Sheffield | 26-ITP-jan | Richard Frimpong | Sprint 1 | Data Groups by Richiealx · Pull Request #1032 · CodeYourFuture/Module-Data-Groups

Richiealx · 2026-03-17T21:49:57Z

Learners, PR Template

Self checklist

I have titled my PR with Region | Cohort | FirstName LastName | Sprint | Assignment Title
My changes meet the requirements of the task
I have tested my changes
My changes follow the style guide

Changelist

This pull request contains my completed work for Sprint 1 - Data Groups.

Fix

Completed the fix exercise by correcting the implementation of:

Sprint-1/fix/median.js

Changes made:

fixed the median calculation
handled both odd and even length arrays correctly
filtered out non-numeric values
returned null when no numeric values are present
avoided mutating the original input array

Implement

Completed the implement exercises by implementing the required functions in:

Sprint-1/implement/sum.js
Sprint-1/implement/max.js
Sprint-1/implement/dedupe.js

I also completed the related test files:

Sprint-1/implement/sum.test.js
Sprint-1/implement/max.test.js
Sprint-1/implement/dedupe.test.js

Implemented functionality includes:

sum - calculates the total of numeric values in an array while ignoring non-numeric elements
findMax - returns the largest numeric value in an array while ignoring non-numeric elements
dedupe - removes duplicate values from an array while preserving the first occurrence

Refactor

Completed the refactor exercise by updating:

Sprint-1/refactor/includes.js

Changes made:

replaced the indexed for loop with a for...of loop
simplified the implementation while keeping the same behaviour
confirmed the function still correctly checks whether the target value exists in the array

Testing

All tests were run locally using:

cd Sprint-1
npm test -- fix
npm test -- implement
npm test -- refactor

…groups

…-data-groups

…data-groups

cjyuan

Code is good. I only have a few suggestions.

Sprint-1/fix/median.js

cjyuan · 2026-03-19T00:19:27Z

Sprint-1/implement/dedupe.test.js

 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("given an array with no duplicates, it returns the same values", () => {
+  expect(dedupe([1, 2, 3])).toEqual([1, 2, 3]);
+});


This test should fail if the function returns the original array (instead of a copy of the original array).

The current test checks only if both the original array and the returned array contain identical elements.
In order to validate the returned array is a different array, we need an additional check.

Can you find out what this additional check is?

cjyuan · 2026-03-19T00:27:15Z

Sprint-1/implement/max.test.js

+test("given an array with non-number values, ignores them and returns the max", () => {
+  expect(findMax(["hey", 10, "hi", 60, 10])).toBe(60);
+});


When a string representing a valid numeric literal (for example, "300") is compared to a number,
JavaScript first converts the string into its numeric equivalent before performing the comparison.
As a result, the expression 20 < "300" evaluates to true.

To test if the function can correctly ignore non-numeric values, you could include a string such as "300" in the test cases.

cjyuan · 2026-03-19T00:28:21Z

Sprint-1/implement/sum.test.js

+test("given an array with decimal numbers, returns the correct sum", () => {
+  expect(sum([1.5, 2.5, 3])).toBe(7);
+});


Decimal numbers in most programming languages (including JS) are internally represented in "floating point number" format. Floating point arithmetic is not exact. For example, the result of 46.5678 - 46 === 0.5678 is false because 46.5678 - 46 only yield a value that is very close to 0.5678. Even changing the order in which the program add/subtract numbers can yield different values.

So the following could happen

expect( 1.2 + 0.6 + 0.005 ).toEqual( 1.805 ); // This fail expect( 1.2 + 0.6 + 0.005 ).toEqual( 1.8049999999999997 ); // This pass expect( 0.005 + 0.6 + 1.2 ).toEqual( 1.8049999999999997 ); // This fail console.log(1.2 + 0.6 + 0.005 == 1.805); // false console.log(1.2 + 0.6 + 0.005 == 0.005 + 0.6 + 1.2); // false

Can you find a more appropriate way to test a value (that involves decimal number calculations) for equality?

Suggestion: Look up

Checking equality in floating point arithmetic in JavaScript

Checking equality in floating point arithmetic with Jest

Hi @cjyuan,

Thank you for the feedback.

I have updated the code and tests based on your comments:

removed the unnecessary extra array clone in median.js

improved the dedupe test so it checks that the returned array is a different array object

updated the max test to include a numeric string such as "300" to confirm non-number values are ignored

changed the decimal sum test to use toBeCloseTo(...) for floating-point comparison

updated sum.js and max.js to use Number.isFinite(...) for stricter numeric checks

fixed the dedupe.js export so the implement tests run correctly

I re-ran all Sprint 1 test suites and all tests are passing.

All these changes sounds good, but your actions somehow introduced merge conflicts to the files. Can you resolve the conflicts?

cjyuan · 2026-03-19T05:50:53Z

Sprint-1/fix/median.js

+<<<<<<< HEAD
+  // Keep only real numeric values
+  const numbersOnly = list.filter(
+    (item) => typeof item === "number" && !Number.isNaN(item)
+  );
+
+  // Return null if the array contains no numbers
+=======
+  // filter() returns a new array, so this does not modify the original input
+  const numbersOnly = list.filter((item) => Number.isFinite(item));
+
+  // Return null if there are no numeric values
+>>>>>>> a22ed15 (Address mentor feedback for sprint 1 data groups)


This is a unresolved merge conflict. You need to delete the "merge conflict markers" and the code that you do not want to keep.

There are several others on the files in this branch.

Can you fix them?

Richiealx added 6 commits March 13, 2026 20:27

Fix median implementation in sprint 1 fix project

c4b663d

Implement sprint 1 array exercises

4ee9bf8

Refactor includes implementation to use for...of loop

1b6cc9b

Merge branch 'coursework/sprint-1-fix' into coursework/sprint-1-data-…

4d87c5a

…groups

Merge branch 'coursework/sprint-1-implement' into coursework/sprint-1…

074cc7c

…-data-groups

Merge branch 'coursework/sprint-1-refactor' into coursework/sprint-1-…

1f24b43

…data-groups

Richiealx added the Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. label Mar 17, 2026

cjyuan reviewed Mar 19, 2026

View reviewed changes

cjyuan added Reviewed Volunteer to add when completing a review with trainee action still to take. and removed Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. labels Mar 19, 2026

Address mentor feedback for sprint 1 data groups

2993b07

Richiealx added the Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. label Mar 19, 2026

cjyuan reviewed Mar 19, 2026

View reviewed changes

cjyuan removed the Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. label Mar 19, 2026

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Sheffield | 26-ITP-jan | Richard Frimpong | Sprint 1 | Data Groups#1032

Sheffield | 26-ITP-jan | Richard Frimpong | Sprint 1 | Data Groups#1032
Richiealx wants to merge 7 commits intoCodeYourFuture:mainfrom
Richiealx:coursework/sprint-1-data-groups

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Richiealx commented Mar 17, 2026

Learners, PR Template

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Changelist

Fix

Implement

Refactor

Testing

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