Plotting a circle on a scatter chart

**Enlighten Me?** · 08-04-2015, 09:59 PM

How can I combine a simple X,Y scatter chart for one series, with an additional series point plotted as a circle with the radius specified in a cell?

Here is a sample data set
A B C
Pt1 0 0
Pt2 1 2
Pt3 1 0
Pt4 2 1
Pt5 1 3

Avg 1 2
R 1.4

Plotting the first set (lines 1-5) on a scatter chart is straight forward; select the data, select scatter chart and let Excel do the rest. Plotting a data point for the Avg data point is simply adding in a new series (right-click chart, "Select Data", then fill in the dialog). Can I plot that second series data point as a circle (on the same scatter chart) with the radius specified in cell B8? If so, please elaborate how it's done.

Thanks!

**Andy Pope** · 08-05-2015, 03:44 AM

You need to create the points to be plot as charts don't really do equation plotting directly.

For each point you want plotted you need to calculate the COS or SIN of the angle, in radians, and muliple by the radius.

**Enlighten Me?** · 08-05-2015, 08:40 AM

Ouch! Thanks, Andy. I was holding on hope for a simple solution. Looks like that might be printing out the scatter chart and getting out the compass.

**Andy Pope** · 08-05-2015, 10:05 AM

It's not that bad.

Chart contains a series for data, Avg point, circle, min/max values and a pie chart.

The min/max series should keep the x and y axis in sync when set to auto.
The pie chart forces the plot area to be square.

You can improve the smoothness of the circle by increasing the number of data points.