Sheffield | 25-ITP-SEP | Declan Williams | Sprint 1 | Data groups #844
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…om filtered numbers
… and empty arrays
…ile preserving first occurrences
…s, returns the largest
…he closest one to zero
…gest decimal number
…ax and ignores non-numeric values
…nd adds numbers to total sum
CatchingKiyoko
added
📅 Sprint 1
| test("given an array with decimal numbers in returns the correct total sum", () => { | ||
| expect(sum([10.5, 20.2, 30.3])).toBe(61.0); | ||
| expect(sum([10.5, -20.2, 30.3])).toBe(20.6); | ||
| }); | ||
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| // Given an array containing non-number values | ||
| // When passed to the sum function | ||
| // Then it should ignore the non-numerical values and return the sum of the numerical elements | ||
| test("given an array containing non-numerical values ignore non-numerical and returns correct total sum", () => { | ||
| expect(sum([2, "hello", 26.5, "hey", -6.6, 8])).toBe(29.9); | ||
| }); |
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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); // falseCan 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
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using toBeCloseTo() in the jest test will help see how close numbers a, b are in to consider to them being equal in values because it accounts for floating-point imprecision, instead of requiring exact bit-for-bit equality
There was a problem hiding this comment.
using toBeCloseTo() in the jest test will help see how close numbers a, b are in to consider to them being equal in values because it accounts for floating-point imprecision, instead of requiring exact bit-for-bit equality as order of operations can affect floating point sums.
cjyuan
added
Reviewed
…nd enhancing code readability
…oko/Module-Data-Groups into Data-Groups-sprint-1
…t using the original array
CatchingKiyoko
added
Needs Review
cjyuan
added
Complete
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All good! Well done. |
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