Excel 2003 radar chart - maximum discrete data points

[Guest]

It appears that while the radar plot can accept thousands of data points, it
is only capable of displaying a maximum of 360 discrete circumferential point
locations. If I plot a single series of 3600 data points (one point for every
1/10 degree) with constant Y values, each single plotted point on the chart
consists of ten overlaying markers. What causes this limitation, and more
importantly, is there a way to overcome it?

 

[Andy Pope]

Hi,

Even with only 360 points the axis lines are almost a solid colour. So I
guess MS decided that 360 is probably more than enough for a radar chart.

What sort of chart are you trying to create? Not a polar chart by chance?

Cheers
Andy

 

[Guest]

Andy,

Thanks for the quick response, but I really had hoped you would tell me that
all I had to do was blah-blah-blah and I could plot all the points I wanted!

I have a 1940's era lab instrument that uses an aging circular chart
recorder to plot the output from several transducers. I need to update it, so
now I'm capturing the digital data stream and have a VBA routine to smooth
and normalize the data, and then plot every 0.1 degrees. An X-Y chart
accurately reflects the smoothed data, but the data looks "choppy" in the
radar plot. Plotting every 1 degree of data results in a smoother looking
series but I wind up throwing away data that I'd rather not. I tried a polar
chart but because the transducers output both + and - values it looks pretty
ugly and difficult to read, and doesn't match the chart recorder output that
everyone's used to seeing (using your 2nd axis tricks I've managed to produce
a digital chart that nicely mimics the analog chart in nearly every way ---
when only 360 points are plotted).

If you're confirming the 360 limitation then I'll revisit the cartesian
solution and see what else I can come up with. Thanks.

 

[Andy Pope]

Ok, so I did some more testing and I can get 3600 data points in a radar
chart. I simply plotted a1:a3600 where each cell contained the formula
=ROW().

The axis labels are a complete mess but the line is drawn.


If you willing to share, privately off NG, what you have currently and
an picture example of desired results I will have a look see.

Cheers
Andy

 

[Guest]

Try this: Fill those 3600 cells with an identical value. Use a simple marker
instead of a line, and make the marker as small as possible. Zoom to 400% and
examine the markers. Instead of 3600 separate markers you'll actually only
see 360, with ten markers stacked directly on top of one another at each one.
Here's another way to see my problem: Instead of using a constant value, use
a repeating series such as 9.1, 9.2 . . . 10.0 to fill the 3600 cells. Format
the value axis scale for a min of 0 and a max of 10. Look at the chart (at
400%) at one of the compass points to see that ten markers are now nicely
aligned in a single row (or column), and that there are 360 total
rows/columns. Change the marker to a continuous line to really see my
dilemma! So, I can plot 3600 points, but point number 9, for example, won't
be plotted at 0.9 degrees but at 1.0 degrees -- along with points 0.6 and 1.2
and seven others.

I will be happy to email you my project later today, and I'd appreciate
tremendously any feedback and help you could offer. Thanks for your interest.

- Daniel

 

[Andy Pope]

I see the problem now. But can't see an way of telling the radar to
increase the number of spokes.

Send me the file and any information about the desired graph and I will
see whats possible.

Cheers
Andy