From cceecc071d1d13c4a12eda9e745e3da783baa6cb Mon Sep 17 00:00:00 2001
From: tina <lt-bloody@riox.eu>
Date: Tue, 31 Jul 2018 15:06:16 +0200
Subject: [PATCH] computes the stats about the period lengths, started tests
---
lib/periode-length.js | 35 +++++++++++++++++++++++++++++++++++
test/periode-length.spec.js | 16 ++++++++++++++++
2 files changed, 51 insertions(+)
create mode 100644 lib/periode-length.js
create mode 100644 test/periode-length.spec.js
diff --git a/lib/periode-length.js b/lib/periode-length.js
new file mode 100644
index 00000000..24456858
--- /dev/null
+++ b/lib/periode-length.js
@@ -0,0 +1,35 @@
+export default function getPeriodLengthStats(cycleLengthArray) {
+ if (Array.isArray(cycleLengthArray) && (cycleLengthArray.length > 0) && cycleLengthArray.every(cycleLength => {
+ return (typeof cycleLength === 'number') && !(isNaN(cycleLength))
+ })) {
+ const PeriodLengthStats = {}
+ const sortedCycleLegthArray = cycleLengthArray.sort((a, b) => {
+ return a - b
+ })
+ PeriodLengthStats.minimum = sortedCycleLegthArray[0]
+ PeriodLengthStats.maximum = sortedCycleLegthArray[cycleLengthArray.length - 1]
+ PeriodLengthStats.mean = cycleLengthArray.reduce(getSum) / cycleLengthArray.length
+ // median
+ if (cycleLengthArray.length % 2 == 1) {
+ PeriodLengthStats.median = sortedCycleLegthArray[(cycleLengthArray.length + 1) / 2 - 1]
+ }
+ else {
+ const middle = cycleLengthArray.length / 2
+ PeriodLengthStats.median = (sortedCycleLegthArray[middle - 1] + sortedCycleLegthArray[middle]) / 2
+ }
+
+ PeriodLengthStats.stdDeviation = 0 // default
+ if (cycleLengthArray.length > 1) {
+ const sumOfSquares = cycleLengthArray.map(cycleLength => {
+ return Math.pow(cycleLength - PeriodLengthStats.mean, 2)
+ }).reduce(getSum)
+ PeriodLengthStats.stdDeviation = Math.sqrt(sumOfSquares / (cycleLengthArray.length - 1 ))
+ }
+ return PeriodLengthStats
+ }
+ console.error('getPeriodLengthStats requiers an array of numbers with length > 0.')
+}
+
+function getSum(total, num) {
+ return total + num
+}
\ No newline at end of file
diff --git a/test/periode-length.spec.js b/test/periode-length.spec.js
new file mode 100644
index 00000000..3051244e
--- /dev/null
+++ b/test/periode-length.spec.js
@@ -0,0 +1,16 @@
+import chai from 'chai'
+import periodInfo from '../lib/period-length'
+
+const expect = chai.expect
+
+describe('it calculates the median correctly', () => {
+ it('works for an odd-numbered array', () => {
+ const periodLengths = [1, 2, 5, 99, 100]
+ const result = periodInfo(periodLengths).median
+ expect(result).to.eql(5)
+ })
+
+ /* it('works for an even-numbered array', () => {
+
+ }) */
+})
\ No newline at end of file
--
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