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POHow to plot a graph real time using coreplot?
 

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  1. POHow to plot a graph real time using coreplot?
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    <p>I'm trying to plot the decibel values of sound on a graph(CPScatterPlot) using coreplot. But the problem is I'm getting the graph with a line that is perpendicular for Y axis, and it's moving up and down on the Y axis with respect to the changes in the decibel values. I need to plot a graph like this. <img src="https://i.stack.imgur.com/GAuRw.png" alt="enter image description here"></p> <p>here is my code: `</p> <pre><code> -(void) generateDataSamples { samples = [[NSMutableArray alloc]initWithCapacity:NUM_SAMPLES]; for (int i=0; i &lt; NUM_SAMPLES; i++) { // peakVal is a variable that holds the decibel value NSDictionary *sample = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithDouble:peakVal],Y_VAL,nil]; [samples addObject:sample]; } } -(NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot; { return [samples count]; } -(NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index{ NSDictionary *sample = [samples objectAtIndex:index]; NSDecimalNumber *num = [NSDecimalNumber zero]; if (fieldEnum == CPScatterPlotFieldX) { num = (NSDecimalNumber *) [NSDecimalNumber numberWithInt:index + 1]; } else if (fieldEnum == CPScatterPlotFieldY) { return [sample valueForKey:Y_VAL]; } return num; } </code></pre> <p>So, what should I do to get a graph as in the figure above? Please help me, I'm new on here.</p> <p>And one more, as you can in the above picture, the Y axis labels are placed inside the plot area, how it can be done?</p> <p>Here is my entire code, please suggest the modifications:</p> <pre><code>#import "MicBlowViewController.h" #import "SecondVC.h" #define DBOFFSET -74.0 #define START_POINT 0.0 #define END_POINT 100.0 #define NUM_SAMPLES 200.0 #define MAX_PEAK 100.0 #define X_VAL @"X_VAL" #define Y_VAL @"Y_VAL" #define S_VAL @"S_VAL" @implementation MicBlowViewController @synthesize avgLabel, peakLabel,absValue,pageControl; -(void)reloadData { if(!graph) { //setting graph double xAxisStart = START_POINT; double xAxisLength = END_POINT - START_POINT; double maxY = 100;//[[samples valueForKeyPath:@"@max.Y_VAL"] doubleValue]; double yAxisStart = START_POINT; double yAxisLength = maxY+3; xVal=START_POINT+0.1; hostingView = [[CPGraphHostingView alloc] initWithFrame:CGRectMake(0, 79, 320, 361)]; [self.view addSubview:hostingView]; graph = [[CPXYGraph alloc] initWithFrame:CGRectMake(0, 79, 320, 361)]; hostingView.hostedGraph = graph; CPTheme *theme = [CPTheme themeNamed:kCPDarkGradientTheme]; [graph applyTheme:theme]; graph.paddingTop = 0.0; graph.paddingBottom = 0.0; graph.paddingLeft = 0.0; graph.paddingRight = 0.0; [[graph defaultPlotSpace] setAllowsUserInteraction:TRUE]; CPXYAxisSet *axisSet = (CPXYAxisSet *)graph.axisSet; axisSet.yAxis.labelOffset=0.1; CPXYAxis *x = axisSet.xAxis; x.majorIntervalLength = CPDecimalFromDouble(10.0); x.orthogonalCoordinateDecimal = CPDecimalFromInteger(0); x.minorTicksPerInterval = 1; CPXYAxis *y = axisSet.yAxis; y.majorIntervalLength=CPDecimalFromDouble(10.0); y.orthogonalCoordinateDecimal = CPDecimalFromInteger(0); y.minorTicksPerInterval = 1; y.tickDirection = CPSignPositive; y.labelAlignment = CPAlignmentLeft; y.alternatingBandFills = [NSArray arrayWithObjects:[[CPColor whiteColor] colorWithAlphaComponent:0.1], [NSNull null], nil]; CPXYPlotSpace *plotSpace = (CPXYPlotSpace *)graph.defaultPlotSpace; plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromDouble(xAxisStart) length:CPDecimalFromDouble(xAxisLength)]; plotSpace.yRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromDouble(yAxisStart) length:CPDecimalFromDouble(yAxisLength)]; CPScatterPlot *dataSourceLinePlot = [[CPScatterPlot alloc] init]; dataSourceLinePlot.dataSource = self; //[dataSourceLinePlot insertDataAtIndex:[samplesY count]-1 numberOfRecords:1]; CPMutableLineStyle *lineStyle = [[dataSourceLinePlot.dataLineStyle mutableCopy] autorelease]; lineStyle.lineWidth = 2.f; lineStyle.lineColor = [CPColor cyanColor]; dataSourceLinePlot.dataLineStyle = lineStyle; [graph addPlot:dataSourceLinePlot]; [dataSourceLinePlot release]; [graph release]; [hostingView release]; } } - (void)generateData { // if (plotData == nil) { NSMutableArray *contentArray = [NSMutableArray array]; for (NSUInteger i = 0; i &lt; 200; i++) { //double test = (double)[peakLabel.text doubleValue]; absValue.text =[NSString stringWithFormat:@"%.2f",peakVal]; id x = [NSDecimalNumber numberWithDouble:1.0 + i ]; id y = [NSDecimalNumber numberWithDouble:peakVal * rand()/(double)RAND_MAX + 0.05]; [contentArray addObject:[NSMutableDictionary dictionaryWithObjectsAndKeys:x, @"x", y, @"y", nil]]; } plotData = [contentArray retain]; //} } -(NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot ; { return [plotData count]; } -(NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index; { NSNumber *num = [[plotData objectAtIndex:index] valueForKey:(fieldEnum == CPScatterPlotFieldX ? @"x" : @"y")]; if (fieldEnum == CPScatterPlotFieldY) { num = [NSNumber numberWithDouble:[num doubleValue]]; } return num; } - (void)viewDidLoad { [super viewDidLoad]; pageControl = [[UIPageControl alloc]init]; [pageControl addTarget:self action:@selector(changePage) forControlEvents:UIControlEventValueChanged]; samplesY = [[NSMutableArray alloc]init]; //checking for sound NSURL *url = [NSURL fileURLWithPath:@"/dev/null"]; NSDictionary *settings = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithFloat: 44100.0], AVSampleRateKey, [NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey, [NSNumber numberWithInt: 1], AVNumberOfChannelsKey, [NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey, nil]; NSError *error; recorder = [[AVAudioRecorder alloc] initWithURL:url settings:settings error:&amp;error]; if (recorder) { [recorder prepareToRecord]; recorder.meteringEnabled = YES; [recorder record]; levelTimer = [NSTimer scheduledTimerWithTimeInterval: 0.03 target: self selector: @selector(levelTimerCallback:) userInfo: nil repeats: YES]; }// else //NSLog([error description]); } - (void)levelTimerCallback:(NSTimer *)timer { // getting decibel values.... [recorder updateMeters]; const double ALPHA = 0.05; double peakPowerForChannel = pow(10, (0.05 * [recorder peakPowerForChannel:0])); lowPassResults = ALPHA * peakPowerForChannel + (1.0 - ALPHA) * lowPassResults; NSLog(@"Average input: %f Peak input: %f Low pass results: %f", [recorder averagePowerForChannel:0], [recorder peakPowerForChannel:0], lowPassResults); peakval=fabs([recorder peakPowerForChannel:0]); double avgval=fabs([recorder averagePowerForChannel:0]); peakVal=MAX_PEAK - peakval; avgVal=MAX_PEAK - avgval; NSLog(@"First: %.2f",peakVal); avgLabel.text=[NSString stringWithFormat:@"%.2f",avgVal]; peakLabel.text=[NSString stringWithFormat:@"%.2f",peakVal]; if (lowPassResults &lt; 0.95) NSLog(@"Mic blow detected: %d",lowPassResults); [self generateData]; [self reloadData]; } - (IBAction) changePage:(id)sender{ SecondVC *vc = [[SecondVC alloc]init]; vc.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:vc animated:YES]; [vc release]; } - (void)dealloc { [peakLabel.text release]; [avgLabel.text release]; [samples release]; [levelTimer release]; [recorder release]; [super dealloc]; } @end </code></pre>
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