Is it possible to create a date plot with irregular date intervals

[Sam Kochukalikkal]

Hi,

Sorry the long post.

I'm trying to plot a graph that has irregular date intervals. Is it possible to plot this date using the format used in the dateplot example. I tried it but the x-axis date labels are incorrect. I believe this is because the dates are not in regular intervals. Below is my code

- (void)createChart

{

// If you make sure your dates are calculated at noon, you shouldn't have to

// worry about daylight savings. If you use midnight, you will have to adjust

// for daylight savings time.

    int nLastIndex = [[self.resultDetailsList reports] count] - 1;

    HistoricalReportDetail *reportDetail = (HistoricalReportDetail *)[[self.resultDetailsList reports] objectAtIndex:nLastIndex];

NSDate *startDate  = [reportDetail collectionDate];

    reportDetail = (HistoricalReportDetail *)[[self.resultDetailsList reports] objectAtIndex:0];

    NSDate *endDate = [reportDetail collectionDate];

    

// Create graph from theme

_graph = [(CPTXYGraph *)[CPTXYGraph alloc] initWithFrame:CGRectZero];

CPTTheme *theme = [CPTTheme themeNamed:kCPTDarkGradientTheme];

[_graph applyTheme:theme];

    

    

    _graph.paddingLeft = 10.0;

    _graph.paddingTop = 10.0;

    _graph.paddingRight = 10.0;

    _graph.paddingBottom = 10.0;

    

    CPTGraphHostingView *hostingView = (CPTGraphHostingView *)[self ChartView];

    hostingView.collapsesLayers = NO;

hostingView.hostedGraph = _graph;

    hostingView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;

    

// Setup scatter plot space

CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)_graph.defaultPlotSpace;

NSTimeInterval xLow  = [startDate timeIntervalSinceReferenceDate];

    NSDate *date = [NSDate dateWithTimeIntervalSinceReferenceDate:xLow];

    NSLog (@"Date Before = %@, Date After = %@", startDate, date);

    

    NSTimeInterval xHigh = [endDate timeIntervalSinceReferenceDate];

plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(xLow - (xHigh - xLow)/10.0f) length:CPTDecimalFromFloat(xHigh - xLow + (xHigh - xLow)/10.0f)];

plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(-2.0) length:CPTDecimalFromFloat(4)];

    

// Axes

CPTXYAxisSet *axisSet = (CPTXYAxisSet *)_graph.axisSet;

CPTXYAxis *x  = axisSet.xAxis;

x.orthogonalCoordinateDecimal = CPTDecimalFromString(@"0.0");

x.minorTicksPerInterval  = 0;

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

dateFormatter.dateStyle = kCFDateFormatterShortStyle;

CPTTimeFormatter *timeFormatter = [[CPTTimeFormatter alloc] initWithDateFormatter:dateFormatter];

timeFormatter.referenceDate = startDate;

x.labelFormatter = timeFormatter;

    x.title = @"Date";

    x.labelRotation = M_PI/4;

    x.titleOffset = 55.5f;

    x.majorIntervalLength = CPTDecimalFromFloat((xHigh - xLow)/10.0f);

    x.labelingPolicy = CPTAxisLabelingPolicyAutomatic;

    

CPTXYAxis *y = axisSet.yAxis;

y.majorIntervalLength  = CPTDecimalFromString(@"0.5");

y.minorTicksPerInterval  = 5;

y.orthogonalCoordinateDecimal = CPTDecimalFromFloat(xLow);

    y.labelingPolicy = CPTAxisLabelingPolicyNone;

    

// Define some custom labels for the data elements

NSArray *customTickLocations = [NSArray arrayWithObjects:[NSDecimalNumber numberWithInt:-1], [NSDecimalNumber numberWithInt:0], [NSDecimalNumber numberWithInt:1],nil];

NSArray *yAxisLabels = [NSArray arrayWithObjects:@"Low", @"Mean", @"High", nil];

NSUInteger labelLocation = 0;

NSMutableArray *customLabels = [NSMutableArray arrayWithCapacity:[yAxisLabels count]];

for ( NSNumber *tickLocation in customTickLocations ) {

CPTAxisLabel *newLabel = [[CPTAxisLabel alloc] initWithText:[yAxisLabels objectAtIndex:labelLocation++] textStyle:y.labelTextStyle];

newLabel.tickLocation = [tickLocation decimalValue];

newLabel.offset  = y.labelOffset + y.majorTickLength;

newLabel.rotation  = M_PI / 2;

[customLabels addObject:newLabel];

}

y.axisLabels = [NSSet setWithArray:customLabels];

    CPTFill *bandFill = [CPTFill fillWithColor:[[CPTColor greenColor] colorWithAlphaComponent:0.3]];

    CPTFill *bandFill2 = [CPTFill fillWithColor:[[CPTColor redColor] colorWithAlphaComponent:0.3]];

    [y addBackgroundLimitBand:[CPTLimitBand limitBandWithRange:[CPTPlotRange plotRangeWithLocation:CPTDecimalFromDouble(-1.0) length:CPTDecimalFromDouble(2.0)] fill:bandFill]];

    [y addBackgroundLimitBand:[CPTLimitBand limitBandWithRange:[CPTPlotRange plotRangeWithLocation:CPTDecimalFromDouble(-2.0) length:CPTDecimalFromDouble(1.0)] fill:bandFill2]];

    [y addBackgroundLimitBand:[CPTLimitBand limitBandWithRange:[CPTPlotRange plotRangeWithLocation:CPTDecimalFromDouble(1.0) length:CPTDecimalFromDouble(1.0)] fill:bandFill2]];

    

    // Create a plot that uses the data source method

CPTScatterPlot *boundLinePlot  = [[CPTScatterPlot alloc] init];

CPTMutableLineStyle *lineStyle = [CPTMutableLineStyle lineStyle];

lineStyle.miterLimit = 1.0f;

lineStyle.lineWidth = 3.0f;

lineStyle.lineColor = [CPTColor blueColor];

boundLinePlot.dataLineStyle = lineStyle;

boundLinePlot.identifier = @"Blue Plot";

boundLinePlot.dataSource = self;

[_graph addPlot:boundLinePlot];

    

// Add plot symbols

CPTMutableLineStyle *symbolLineStyle = [CPTMutableLineStyle lineStyle];

symbolLineStyle.lineColor = [CPTColor blackColor];

CPTPlotSymbol *plotSymbol = [CPTPlotSymbol ellipsePlotSymbol];

plotSymbol.fill = [CPTFill fillWithColor:[CPTColor blueColor]];

plotSymbol.lineStyle = symbolLineStyle;

plotSymbol.size = CGSizeMake(10.0, 10.0);

boundLinePlot.plotSymbol = plotSymbol;

    

// Add some data

NSMutableArray *newData = [NSMutableArray array];

NSUInteger i;

    NSArray *reports = self.resultDetailsList.reports;

    

for ( i = 0; i < [reports count]; i++ ) {

        HistoricalReportDetail *hr = (HistoricalReportDetail *) [reports objectAtIndex:i];

id y = [NSDecimalNumber numberWithFloat:[[hr testNormalizedResultValue] floatValue]];

        NSTimeInterval x = [[hr collectionDate] timeIntervalSinceReferenceDate];

        NSLog(@"Date before = %@, Date after = %@", [hr collectionDate], [NSDate dateWithTimeIntervalSinceReferenceDate:x]);

[newData addObject:

[NSDictionary dictionaryWithObjectsAndKeys:

 [NSDecimalNumber numberWithFloat:x], [NSNumber numberWithInt:CPTScatterPlotFieldX],

 y, [NSNumber numberWithInt:CPTScatterPlotFieldY],

 nil]];

}

    self.dataForPlot = newData;

}

Data:

X: 2011-08-21 Y: 0.99

X: 2011-08-22 Y: 0.99

X: 2011-08-22 Y: -2

X: 2011-08-23 Y: 0.09

X: 2011-08-23 Y: -2

X: 2011-08-24 Y: 0.99

X: 2011-08-25 Y: 0.09

X: 2011-08-29 Y: 0.09

As you can see the plot matches the data but the x-axis labels are wrong. Any help would be much appreciated.

thx

Sam

[Sam Kochukalikkal]

Got it to work. I just removed reference date assignment to the CPTTimeFormatter. Thanks for a wonderful and seamless charting tool.

thx
sam

[Tik Sathaphorn]

Hi Same, 

I have the same problem too but i get idea from your code .

Can i have your code on 

- (double)doubleForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)idx {}

Thanks