swift - "ios-charts" Do not draw empty or zero values. & Interpolate values on combined chart -

my question 2 fold logic may similar.

i have simple candlestick chart 2 different indicators. 1 @ bottom , other overlayed on top of candlestick data. (see screenshot)

first: in lower chart not want draw values before calculated. in case 14 periods simple moving average. (see screenshot yellow box. not want draw these values)

second: on overlay want "open", lowest value, highest value, , "close" of last bar. want draw line between these 4 points , ignore data in-between. (it should yellow line in screenshot).

how can reformat set chart function ignore values before 14 periods on lower line chart?

how can ignore other points , interpolate between 4 values on line chart combined view?

currently have set values want "ignored" 0 (1950 in screenshot make readable , not squashed) around out of bounds errors.

tried simplify code as possible make more readable here:

// //  viewcontroller.swift //  import foundation import cocoa import charts  var yvaluesindicatorlower: [double] = [] var yvaluesindicatoroverlay: [double] = []  class viewcontroller: nsviewcontroller {      //chart view outlets      @iboutlet weak var combinedchartview: combinedchartview!      @iboutlet weak var linechartview: linechartview!      // zoom buttons      @ibaction func zoomall(sender: anyobject) {         combinedchartview.fitscreen()         linechartview.fitscreen()     }      @ibaction func zoomin(sender: anyobject) {         combinedchartview.zoomin()         linechartview.zoomin()     }      @ibaction func zoomout(sender: anyobject) {         combinedchartview.zoomout()         linechartview.zoomout()     }       override func viewdidload() {         super.viewdidload()          // additional setup after loading view.          view.wantslayer = true         view.layer?.backgroundcolor = nscolor(red: 0.2, green: 0.2, blue: 0.2, alpha: 0.95).cgcolor          combinedchartview.nodatatext = "loading data..."         linechartview.nodatatext = "loading data..."          // additional setup after loading view.         let xvalues = ["05-16", "05-17", "05-18", "05-19", "05-20", "05-23", "05-24", "05-25", "05-26", "05-27", "05-31", "06-01", "06-02", "06-03", "06-06", "06-07", "06-08", "06-09", "06-10", "06-13", "06-14", "06-15", "06-16", "06-17", "06-20", "06-21", "06-22", "06-23", "06-24", "06-27", "06-28", "06-29", "06-30", "07-01", "07-05", "07-06", "07-07", "07-08", "07-11", "07-12", "07-13", "07-14", "07-15", "07-18", "07-19", "07-20", "07-21", "07-22", "07-25", "07-26", "07-27", "07-28", "07-29", "08-01", "08-02", "08-03"]          ////prices ["open"=[0], "high"=[1], "low"=[2], "last"[3]]         let yvalues: [[double]] = [[2032.75, 2060.0, 2027.0, 2053.5], [2052.5, 2061.0, 2028.75, 2036.5], [2035.75, 2049.5, 2022.75, 2034.75], [2035.75, 2036.25, 2014.0, 2030.5], [2030.5, 2047.5, 2029.5, 2042.0], [2043.75, 2047.5, 2035.25, 2036.75], [2037.5, 2069.0, 2032.75, 2067.0], [2066.5, 2084.25, 2065.75, 2080.75], [2080.5, 2083.75, 2074.5, 2083.0], [2082.0, 2090.25, 2080.0, 2090.25], [2091.25, 2095.25, 2078.0, 2086.25], [2085.0, 2090.75, 2075.0, 2088.75], [2088.75, 2096.0, 2078.25, 2095.25], [2094.5, 2097.25, 2074.0, 2088.25], [2088.5, 2103.25, 2085.25, 2099.75], [2099.25, 2108.75, 2098.0, 2101.75], [2101.25, 2110.75, 2098.0, 2108.5], [2108.5, 2109.5, 2097.25, 2104.75], [2104.5, 2104.75, 2079.5, 2087.0], [2081.0, 2089.25, 2066.5, 2067.25], [2067.25, 2072.75, 2054.75, 2064.75], [2064.5, 2079.5, 2059.75, 2062.5], [2062.5, 2071.5, 2040.75, 2069.5], [2068.75, 2074.75, 2053.25, 2059.75], [2071.0, 2092.5, 2070.25, 2082.75], [2079.0, 2086.0, 2074.0, 2079.25], [2079.25, 2091.25, 2075.25, 2077.0], [2083.0, 2113.25, 2083.0, 2113.25], [2115.75, 2119.5, 1999.0, 2018.25], [2013.75, 2022.5, 1981.5, 1982.0], [1982.5, 2029.75, 1982.25, 2028.25], [2028.25, 2074.75, 2022.75, 2074.25], [2072.25, 2091.25, 2056.5, 2086.5], [2086.5, 2100.75, 2081.5, 2096.25], [2099.75, 2104.75, 2072.5, 2084.5], [2084.0, 2094.5, 2065.75, 2093.0], [2092.0, 2102.0, 2081.75, 2092.25], [2092.0, 2125.5, 2087.5, 2120.75], [2120.25, 2136.75, 2120.0, 2130.5], [2130.75, 2149.25, 2128.5, 2146.0], [2145.75, 2152.25, 2139.5, 2145.75], [2145.25, 2168.0, 2142.75, 2157.75], [2156.5, 2164.75, 2143.25, 2146.0], [2154.5, 2163.25, 2152.75, 2160.25], [2160.0, 2160.75, 2151.25, 2159.0], [2159.0, 2169.75, 2155.25, 2168.75], [2168.25, 2170.25, 2153.5, 2159.25], [2159.0, 2169.25, 2156.0, 2167.25], [2167.75, 2172.5, 2155.75, 2163.25], [2162.75, 2168.0, 2153.75, 2166.0], [2166.0, 2169.25, 2152.0, 2163.25], [2162.75, 2168.5, 2153.5, 2166.0], [2165.5, 2171.75, 2157.5, 2171.0], [2174.0, 2177.75, 2159.75, 2165.5], [2166.0, 2171.0, 2141.5, 2153.0], [2152.25, 2158.25, 2145.25, 2156.75]]          //pass values indicators , returned indicator values         yvaluesindicatoroverlay = indicatoroverlay(yvalues)         yvaluesindicatorlower = indicatorlower(yvalues)          //pass values chart setting function         setchart(xvalues, valuescandlechart: yvalues, indicatorlowervalues: yvaluesindicatorlower, indicatoroverlayvalues: yvaluesindicatoroverlay)     }       func indicatoroverlay(yvalues: [[double]]) -> [double]{          var highest = double()         var zigzag: [double] = []          in 0..<yvalues.count {             highest = max(highest, yvalues[i][1])         }          var lowest = highest         in 0..<yvalues.count {             lowest = min(lowest, yvalues[i][2])         }          in 0..<yvalues.count {             if == 0 {                 zigzag.append(yvalues[i][0])             }             else if yvalues[i][1] == highest {                 zigzag.append(highest)             }             else if yvalues[i][2] == lowest {                 zigzag.append(lowest)             }             else if == yvalues.count-1 {                 zigzag.append(yvalues[i][3])             }             else {                 zigzag.append(0)//these values should ignored , interpolated between other values.             }         }         print(highest)         print(lowest)          return zigzag      }      func indicatorlower(yvalues: [[double]]) -> [double]{          let peroid = 14.0          var sum = 0.0         var sma: [double] = []          //simple moving average         in 0..<int(peroid) {             sum  += yvalues[i][3]             if < int(peroid)-1 {                 sma.append(0)//these values ignored             }         }         sma.append(sum/peroid)         in int(peroid)..<yvalues.count {             sum = (sum - yvalues[i - int(peroid)][3]) + yvalues[i][3]             sma.append(sum/peroid)         }          return sma      }      //function set chart values      func setchart(xvalues: [string], valuescandlechart: [[double]], indicatorlowervalues: [double], indicatoroverlayvalues: [double]) {           var yvalscandlechart : [candlechartdataentry] = []          in 0..<valuescandlechart.count {             let high = valuescandlechart[i][1]             let low = valuescandlechart[i][2]             let open = valuescandlechart[i][0]             let close = valuescandlechart[i][3]              yvalscandlechart.append(candlechartdataentry(xindex: i, shadowh: high, shadowl: low, open: open, close: close))         }          //how ignore values "0" or below set index?         var indicatorlower_yvalues: [chartdataentry] = []          in 0..<xvalues.count {             let indicatorlower_yvalue = chartdataentry(value: indicatorlowervalues[i], xindex: i)             indicatorlower_yvalues.append(indicatorlower_yvalue)         }          //how use vlaues calculated , not "0" draw zigzag across candlestick chart?         var indicatoroverlay_yvalues: [chartdataentry] = []          in 0..<xvalues.count {             let indicatoroverlay_yvalue = chartdataentry(value: indicatoroverlayvalues[i], xindex: i)             indicatoroverlay_yvalues.append(indicatoroverlay_yvalue)         }          let candlechartdataset = candlechartdataset(yvals: yvalscandlechart, label: "price")         let lineoverlaychartdataset = linechartdataset(yvals: indicatoroverlay_yvalues, label: "indicatoroverlay")          let data: combinedchartdata = combinedchartdata(xvals: xvalues)          data.candledata = candlechartdata(xvals: xvalues, datasets: [candlechartdataset])         data.linedata = linechartdata(xvals: xvalues, datasets: [lineoverlaychartdataset])         combinedchartview.draworder = [3, 2]          combinedchartview.data = data          candlechartdataset.decreasingcolor = nscolor.redcolor()         candlechartdataset.increasingcolor = nscolor.greencolor()         candlechartdataset.neutralcolor = nscolor.bluecolor()         candlechartdataset.shadowcolorsameascandle = true         candlechartdataset.shadowwidth = 1         candlechartdataset.decreasingfilled = true         candlechartdataset.increasingfilled = false         candlechartdataset.drawvaluesenabled = false         combinedchartview.doubletaptozoomenabled = false         lineoverlaychartdataset.drawcirclesenabled = false         lineoverlaychartdataset.drawvaluesenabled = false          let linechartdataset = linechartdataset(yvals: indicatorlower_yvalues, label: "indicatorlower")         let linechartdata = linechartdata(xvals: xvalues, dataset: linechartdataset)         linechartview.data = linechartdata           linechartview.doubletaptozoomenabled = false         linechartdataset.drawcirclesenabled = false         linechartdataset.drawvaluesenabled = false       }      override var representedobject: anyobject? {         didset {             // update view, if loaded.         }     }   } 

wow easy... =]

shows how library.

per suggestion on issue here: linechartview avoid painting 0 values #830

all had change these:

    //how ignore values "0" or below set index?     var indicatorlower_yvalues: [chartdataentry] = []      in 0..<xvalues.count {         let indicatorlower_yvalue = chartdataentry(value: indicatorlowervalues[i], xindex: i)         indicatorlower_yvalues.append(indicatorlower_yvalue)     }      //how use vlaues calculated , not "0" draw zigzag across candlestick chart?     var indicatoroverlay_yvalues: [chartdataentry] = []      in 0..<xvalues.count {         let indicatoroverlay_yvalue = chartdataentry(value: indicatoroverlayvalues[i], xindex: i)         indicatoroverlay_yvalues.append(indicatoroverlay_yvalue)     } 

to these:

        //ignore values "0"         var indicatorlower_yvalues: [chartdataentry] = []          in 0..<xvalues.count {             if indicatorlowervalues[i] != 0 {//add: if clause skip "0"                 let indicatorlower_yvalue = chartdataentry(value: indicatorlowervalues[i], xindex: i)                 indicatorlower_yvalues.append(indicatorlower_yvalue)             }         }          //use vlaues not "0" draw zigzag         var indicatoroverlay_yvalues: [chartdataentry] = []          in 0..<xvalues.count {             if indicatoroverlayvalues[i] != 0 {//add: if clause skip "0"                 let indicatoroverlay_yvalue = chartdataentry(value: indicatoroverlayvalues[i], xindex: i)                 indicatoroverlay_yvalues.append(indicatoroverlay_yvalue)             }         }