topic Re: label multiple ellipses in biplot in Discussions

label multiple ellipses in biplot

Anonymous — Mon, 20 Aug 2018 14:43:05 GMT

Dear Community,

Is there an easy way to label multiple ellipses in a biplot without adding individual annotations?

Thank you,

-Lucas

Re: label multiple ellipses in biplot

Phil_Kay — Thu, 23 Aug 2018 08:03:40 GMT

Hi,

How did you create the ellipses? They don't appear to have any data associated with them. I think we would need to understand that to offer a solution.

Thanks,
Phil

Re: label multiple ellipses in biplot

Anonymous — Thu, 23 Aug 2018 12:58:03 GMT

Hi Phil,

I am analyzing geochemistry (parts per million concentrations) from obsidian rock of which there are multiple groups or sources of obsdian. The ellipses are created from grouping multiple samples of obsidian source reference material (n=>5), applying 95% confidence ellipses based on these source samples, then hiding the source sample points, and then plotting the unknown samples relative to those ellipses to determine what source they are from. I am trying to label the ellipses by my source groups. In the past, I have inserted annotations with the obsidian reference material name, but this becomes time consuming if I want to repeat the analysis with new data.

Thank you,

-Lucas

Re: label multiple ellipses in biplot

Mark_Bailey — Thu, 23 Aug 2018 13:01:43 GMT

In addition to Phil's help, I suggest that you study the Discriminant platform. You can build a model from the known sources (supervised learning) and then classify new samples based on the model.

Re: label multiple ellipses in biplot

Phil_Kay — Thu, 23 Aug 2018 13:02:34 GMT

Thanks for the explanation. I think that a solution would be to overlay with a data point for the means of each obsidian source reference material. Then you can label these points but make them invisible. I'll have a look later to see if I can find the simplest way to do this. Unless someone else provides a solution in the meantime...

Re: label multiple ellipses in biplot

Anonymous — Thu, 23 Aug 2018 13:06:44 GMT

Thank you Phil. How do I plot a mean point for each source?

Re: label multiple ellipses in biplot

Anonymous — Thu, 23 Aug 2018 13:07:50 GMT

Thank you. I will look into this further. I have used the distriminate function but not for creating a model.

Re: label multiple ellipses in biplot

Phil_Kay — Fri, 24 Aug 2018 13:08:38 GMT

Okay, a better solution:

1. Make the ellipse plot with the points graph element as well

2. Select one of the data points from each source and then right-click > Rows > Label

You should have a label for each source ellipse now - assuming you have defined the source colunm as a label)

Now you want to get rid of the points from the plot. Actually we will just make them invisible.

3. Select the rows for the points that define the ellipses and define the marker for the rows as a space character, " " (Rows > Markers > Others...)

See the example data table with Graph Builder script.

Re: label multiple ellipses in biplot

Anonymous — Fri, 24 Aug 2018 13:16:05 GMT

Thank you Phil. I will give this a try. I follow your instructions.