CorePlot - 設置y軸範圍以包含所有數據點

Question

我在iOS應用程序中實現了CorePlot圖形，但是我無法根據集合中的數據點動態調整y軸的大小。一些數據集範圍從10-50，而其他數據集範圍從400-500。在這兩種情況下，我都想看到y-origin（0）。

我已經使用scaletofitplots方法嘗試：

[graph.defaultPlotSpace scaleToFitPlots:[graph allPlots]]; 

但這對圖形沒有任何影響，他們依然表現出0到1

的唯一方法默認的Y軸範圍的我可以改變Y軸是通過這種手工進行：

graph.defaultPlotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(0.0f)) length:CPTDecimalFromFloat(500.0f)]; 

但是這不適合用於更小的範圍（10-50）的圖表工作，你可以想像。

是否有任何方法從我的數據集中檢索最高的y值，以便我可以手動將最大y軸設置爲該值？還是有更好的選擇？

編輯：這裏是我使用的文件：

#import "TUTSimpleScatterPlot.h" 

@implementation TUTSimpleScatterPlot 

@synthesize hostingView = _hostingView; 
@synthesize graph = _graph; 
@synthesize graphData = _graphData; 

-(id)initWithHostingView:(CPTGraphHostingView *)hostingView andData:(NSMutableArray *)data { 
    self = [super init]; 

    if (self != nil) { 
     self.hostingView = hostingView; 
     self.graphData = data; 
     self.graph = nil; 
    } 
    return self; 
} 

-(void)initialisePlot { 

    if ((self.hostingView == nil) || (self.graphData == nil)) { 
     NSLog(@"TUTSimpleScatterPlot: Cannot Initialise plot with hosting view and data"); 
     return; 
    } 

    if (self.graph != nil) { 
     NSLog(@"TUTSimpleScatterPlot: Graph Object already exists."); 
    } 
    NSDate *refDate = [NSDate date]; 
    NSTimeInterval oneDay = 24 * 60 * 60; 

    CGRect frame = [self.hostingView bounds]; 
    self.graph = [[CPTXYGraph alloc] initWithFrame:frame]; 

    CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)self.graph.defaultPlotSpace; 
    plotSpace.allowsUserInteraction = YES; 
    plotSpace.delegate = self; 
    self.graph.plotAreaFrame.paddingBottom = 20.0f; 
    self.graph.plotAreaFrame.paddingLeft = 35.0f; 


    self.hostingView.hostedGraph = self.graph; 

    CPTMutableLineStyle *lineStyle = [CPTMutableLineStyle lineStyle]; 
    lineStyle.lineColor = [CPTColor whiteColor]; 
    lineStyle.lineWidth = 2.0f; 

    CPTMutableLineStyle *lineStyleThin = [CPTMutableLineStyle lineStyle]; 
    lineStyleThin.lineColor = [CPTColor whiteColor]; 
    lineStyleThin.lineWidth = 1.0f; 

    CPTMutableTextStyle *textStyle = [CPTMutableTextStyle textStyle]; 
    textStyle.fontName = @"HelveticaNeue-Medium"; 
    textStyle.fontSize = 10; 
    textStyle.color = [CPTColor whiteColor]; 

    CPTMutableLineStyle *plotSymbolLineStyle = [CPTMutableLineStyle lineStyle]; 
    plotSymbolLineStyle.lineColor = [CPTColor whiteColor]; 
    plotSymbolLineStyle.lineWidth = 1.0f; 

    CPTPlotSymbol *plotSymbol = [CPTPlotSymbol ellipsePlotSymbol]; 
    plotSymbol.lineStyle = plotSymbolLineStyle; 
    plotSymbol.fill = [CPTFill fillWithColor:[CPTColor colorWithComponentRed:0.4 green:0.6 blue:0.8 alpha:1.0]]; 
    plotSymbol.size = CGSizeMake(8.0, 8.0); 

    CPTScatterPlot *plot = [[CPTScatterPlot alloc] init]; 
    plot.dataSource = self; 
    plot.identifier = @"mainPlot"; 

    [plotSpace scaleToFitPlots:[graph allPlots]]; 

    CPTMutablePlotRange *yRange = [plotSpace.yRange mutableCopy]; 
    [yRange expandRangeByFactor:CPTDecimalFromDouble(615)]; 
    plotSpace.yRange = yRange; 

    plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(oneDay - (oneDay * 6.3f)) length:CPTDecimalFromFloat(oneDay * 6.6f)]; 
    plotSpace.allowsUserInteraction = YES; 

    CPTPlotRange *globalYRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromDouble(0.0f) length:CPTDecimalFromDouble(615.0f)]; 
    plotSpace.globalYRange = globalYRange; 

    // Modify the graph's axis with a label, line style, etc 
    CPTXYAxisSet *axisSet = (CPTXYAxisSet *)self.graph.axisSet; 

    axisSet.xAxis.axisConstraints = [CPTConstraints constraintWithLowerOffset:0.0]; 
    axisSet.xAxis.axisLineStyle = lineStyle; 
    axisSet.xAxis.majorTickLineStyle = lineStyle; 
    axisSet.xAxis.labelTextStyle = textStyle; 
    axisSet.xAxis.labelOffset = 1.0f; 
    axisSet.xAxis.majorIntervalLength = CPTDecimalFromFloat(oneDay*1); 
    axisSet.xAxis.orthogonalCoordinateDecimal = CPTDecimalFromString(@"0.0"); 
    axisSet.xAxis.minorTicksPerInterval = 0; 
    axisSet.xAxis.majorTickLength = 0.0f; 
    axisSet.xAxis.majorGridLineStyle = majorGridLineStyle; 

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 
    [dateFormatter setDateFormat:@"dd MMM"]; 
    CPTTimeFormatter *timeFormatter = [[CPTTimeFormatter alloc] initWithDateFormatter:dateFormatter]; 
    timeFormatter.referenceDate = refDate; 
    axisSet.xAxis.labelFormatter = timeFormatter; 

    axisSet.yAxis.axisLineStyle = lineStyle; 
    axisSet.yAxis.majorTickLineStyle = lineStyle; 
    axisSet.yAxis.minorTickLineStyle = lineStyleThin; 
    axisSet.yAxis.labelTextStyle = textStyle; 
    axisSet.yAxis.labelOffset = 3.0f; 
    axisSet.yAxis.majorIntervalLength = CPTDecimalFromString(@"50.0"); 
    axisSet.yAxis.minorTicksPerInterval = 1; 
    axisSet.yAxis.minorTickLength = 3.0; 
    axisSet.yAxis.majorTickLength = 5.0; 
    axisSet.yAxis.orthogonalCoordinateDecimal = CPTDecimalFromFloat(0); 
    axisSet.yAxis.majorGridLineStyle = majorGridLineStyle; 

    axisSet.yAxis.axisConstraints = [CPTConstraints constraintWithLowerOffset:0.0]; 

    CPTMutableLineStyle *theLineStyle = [CPTMutableLineStyle lineStyle]; 
    theLineStyle.lineColor = [CPTColor colorWithComponentRed:0.3 green:0.6 blue:0.9 alpha:1.0]; 
    theLineStyle.lineWidth = 2.0f; 

    plot.dataLineStyle = theLineStyle; 
    plot.plotSymbol = plotSymbol; 

    [self.graph addPlot:plot]; 

} 

Answer 1

它看起來像你正確使用-scaleToFitPlots:。如果需要，此方法將更新繪圖數據。確保在調用數據源之前，正確的數據可用於數據源。

編輯基於新代碼：

-scaleToFitPlots:添加劇情圖形之前被調用。因此-allPlots數組是空的，沒有比例。繪圖生成並添加到圖形後，移動縮放操作。