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ScatterPlot of the Night Sky

The Polar chart (also known as the Radar chart) may be used in several ways to handle cyclic timeseries or comparisons on many dimensions. If it is called with a simple list of numbers, it treats each value as a logical axis and simply plots the values out as a star shape with as many points as there were values.

This example is genuinely Polar data, so it is best plotted around a circle. The y-values are altitude (but of course 90 is at the Zenith) and the x-values give the direction of the observation.

This chart could also be used with daily data, for example a count of web-site hits over 24 hours.

SharpPlot sp = new SharpPlot;

altitude = new int[] {8,42,1,38,20,35,34,28,22,50,52,40,30,10,7,41,41,17,11,30,5,8,
         42,42,19,24,57,38,32,4,19,40,41,49};
azimuth = new int[] {48,42,55,63,48,51,75,41,32,51,51,38,48,57,35,54,23,70,54,40,55,
         38,69,70,64,35,69,37,77,80,33,47,45,25};

sp.PolarChartStyle = PolarChartStyles.Markers|PolarChartStyles.GridLines|
         PolarChartStyles.CompassPlot|PolarChartStyles.NoLines;
sp.YAxisStyle = YAxisStyles.ForceZero;
sp.Heading = "Meteors sighted\n18th Nov";
sp.HeadingStyle = HeadingStyles.Left;

sp.SetMargins(24,12,0,0);

sp.SetXLabels(new string[]{"NE","East","SE","South","SW","West","NW","North"});
sp.SetXTickMarks(45,3);
sp.SetYTickMarks(new int[] {0,30,60,90});
sp.SetXLabelFont("arial",8,FontStyle.Regular,Color.Maroon);
sp.SetYLabelFont("arial",8,FontStyle.Regular,Color.White);
sp.YAxisStyle = YAxisStyles.InvertAxis|YAxisStyles.InvisibleAxis;
sp.SetChartBackground(Color.Navy,FillStyle.Saturate80);
sp.LabelStyle = LabelStyles.Opaque;  // Background for circle - also May 03
sp.SetMarkers(Marker.Bullet);
sp.SetColors(Color.White);

sp.DrawPolarChart(altitude,azimuth);

Worked Examples

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