5575 Views 10 Replies Latest reply: Mar 3, 2010 5:21 PM by Badunit
If I undertand what you are looking for, plotting an area diagram of
1) Your data as one series and
2) The negative of your data as another series and
3) Setting the two colors the same
will give a kite-like diagram of a single data set. Is that what you've done so far? Multiple data sets would require a different method.
Can you post a screen shot or image of what you are looking to do?
The way I get it is that the method is generally used to compare two sets of similar data, so for instance, sample set one would be plotted above the line and sample set two would be plotted below the line, producing a somewhat mirror image. I don't know what the advantage is, but it seems to be popular in the life sciences.
The ones I saw online were actual mirror images with "species presence recorded around an invisible central axis to produce a series of kite-like shapes which show species fading in and out along the transect."
This is easy to do with a single data set using Y=0 as the central axis. To create a single series above the zero line is still pretty easy using a stacked area chart and some simple math. Getting two or more series on a chart I have not figured out other than with overlying charts.
Hey guys, thanks for all the replies. Yes, kite diagrams are very useful in biology, for example, we're doing a study along a line transect on a rocky shore near the beach, and are taking 1sqm quadrat samples of organisms along that line, and comparing the organisms' population density, abundance, etc.
Anyway, this is what I have so far using an area chart: http://img709.imageshack.us/img709/2252/screenshot20100304at724.png
As you can see, using positive and negative values works, except that "Barnacle A" and "Barnacle B" are both on the same Y-value, whereas they each need separate Y-value marks, as seen here:
Is there an easy way to flip it so that those "Y-values" (the percentage cover, essentially) go on the x-axis, and the distance goes on the y-axis? Prob. easy, I know, but yeah..been a long night!
This is two overlaid charts. Is that close to what you're looking for?
Column C =200-B
Column D = 2*B
Column F = 80-E
Column G = 2*E
I created a stacked bar chart for C&D and another for F&G. The two series corresponding to C and F I set to no fill in the Graphic Inspector. I removed most of the elements of the second chart, set the chart fill color to none, ensured the two charts had the same max Y value on the axis (before hiding the Y axis value labels), made sure the two charts were the same size, and did a few other things then slid the second chart over the first. Kind of a pain but this is the result.
I would recommend having a table with the data and another table for the mathematical manipulations and use the second table for creating the chart(s). That's not what I did but I recommend doing it that way. There are also other ways you could manipulate the data and make and overlay charts. You could just chart +/-Y data on multiple charts and overlay them so the Y axis aligns on each but the X axis does not and have one blank chart in there to provide the X and Y axis.
I tried it with +/-Y charts overlaid on each other. One problem is that it leaves a thin white line down the centerline of the kites. It also didn't seem quite as easy and I could not use the chart legend because the second series in each chart (the -Y data) shows up as an extra colored square in the legend.