Struct inside struct Equatable count duplicate item Swift - arrays

Question

The answer I found is with one level of struct. In my code I want to find out how many same dates is in inside of the struct of the struct. I never use equatable before so I'm not sure how to implement it with struct inside struct.
I'm using Charts pod and the array chartMetricItemSets contains different readings with multiples days. ex: ["name": sugar, [["date": "Oct 10", "value": 120], ["date": "Oct 10", "value": 121], ["date": "Oct 11", "value": 120], ["date": "Oct 13", "value": 120], ["date": "Oct 13", "value": 121]]. The xAxisDates will be ["Oct 10", "Oct 11", "Oct 13"]
the x is the date and the y is for the same date sums
Goal: chartDataEntries should append [x:0(10/10), y:241], [x:1(10/11), y:120], [x:2(10/13), y: 241]
Thank you!
struct ChartData {
let name: String
let value: [ChartValue]
}
struct ChartValue {
let date: Date
let value: Double
}
var chartMetricItemSets = [[ChartData]]()
var xAxisDates = [String]() //date array
func getChartDataSets() {
for (index, chartHealthItemSet) in chartMetricItemSets.enumerated() {
let dataSourceSelected = dataSourcesSelected[index]
var chartDataEntries = [ChartDataEntry]() //array display on graph
var chartYaxis: Double = 0
var datePoint: Int = 0
var countChartYaxis = 0
var duplicateDateCount = 0
for (index, item) in chartHealthItemSet[0].value.enumerated() {
for (dateIndex, date) in xAxisDates.enumerated() {
if item.date.convertDateToString(dateFormat: .monthDay) == date {
chartYaxis += item.value
datePoint = dateIndex
chartYaxis += 1
break
}
//missing counting duplicateDateCount
if duplicateDateCount == countChartYaxis {
chartDataEntries.append(ChartDataEntry(x: Double(datePoint), y: chartYaxis.roundUpNDecimal(n: 2)))
}
}
print("chartYaxis: \(chartYaxis)")
print("chartDataEntries: \(chartDataEntries)")
}
chartDataEntries.sort(by: { $0.x < $1.x })
let set = LineChartDataSet(entries: chartDataEntries,
label: HEALTH_TABLE.allCases[dataSourceSelected].info.name)
set.mode = .linear // cubic line effect (smoother)
set.colors = [HEALTH_TABLE.allCases[dataSourceSelected].info.chartColor]
set.setCircleColor(.black)
set.lineWidth = 1.5
set.circleRadius = 3
set.drawCircleHoleEnabled = false
set.drawCirclesEnabled = true
set.drawHorizontalHighlightIndicatorEnabled = true
lineChartData?.addDataSet(set)
}
chartView.xAxis.valueFormatter = IndexAxisValueFormatter(values: xAxisDates)
chartView.xAxis.granularity = 1
chartView.xAxis.axisMinLabels = 4
chartView.xAxis.axisMaxLabels = 6
DispatchQueue.main.async {
self.chartView.data = self.lineChartData
}
}

Answer 1

In Swift 4 a useful API was introduced to group arrays to dictionaries by an arbitrary predicate.
You can group chartHealthItemSet[0]
let grouped = Dictionary(grouping: chartHealthItemSet[0], by: {$0.date.convertDateToString(dateFormat: .monthDay)}
The result is ["10/10":[ChartData], "10/11":[ChartData], ...]
Sort the keys and assign them to xAxisDates
xAxisDates = grouped.keys.sorted()
To get the sum of the values get the array from the grouped dictionary for the date key, map it to the values and sum them up
for (index, date) in xAxisDates.enumerated() {
let sum = grouped[date]!.map{$0.value}.reduce{0.0, +}
chartDataEntries.append(ChartDataEntry(x: Double(index), y: sum.roundUpNDecimal(n: 2)))
}