Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: duplicate data points in scatterplot
Replies: 4   Last Post: Dec 9, 2012 9:20 PM

 Messages: [ Previous | Next ]
 dpb Posts: 9,850 Registered: 6/7/07
Re: duplicate data points in scatterplot
Posted: Nov 4, 2009 4:36 PM

ruud verschaeren wrote:
...
> I have a scatter plot with some duplicate data points. The standard
> code writes these on top of each other. In statistical programs they
> have ways of showing this is a double or triple data point. In matlab
> I haven't found these methods. Are there standard formulas or file
> exchange scripts that do this? I had a look but found nothing.
>
> some examples: sunflowerplot and jitterplot:
> http://www.ats.ucla.edu/stat/spss/faq/jitter.htm
>
> is there something around for Matlab?

...
If file exchange didn't uncover it, perhaps not.

Doesn't look like the jitter solution would be too difficult to
implement, however. Add a percentage factor onto each data point
coordinate for each duplicate entry--of course it ends up w/ the
question in general of "what's a duplicate?" in floating point
comparisons possibly as well as just how many duplicate points do you
really want to be able actually discern?

Another solution I've seen (altho I don't have a handy example to link
to) uses a circle or other figure and adjust its size so the area (or
diameter) is proportional to the number of points.

Yet another would be to annotate the locations w/ the number of points
textually.

But, to answer the original question, "I don't know"... :)

--

Date Subject Author
11/3/09 ruud verschaeren
11/4/09 dpb
11/4/09 cyclist
5/28/12 Jemma
12/9/12 Stuart Layton