[R] Scatterplot Showing All Points

Duncan Murdoch murdoch at stats.uwo.ca
Tue Dec 18 04:43:50 CET 2007

On 17/12/2007 8:14 PM, Wayne Aldo Gavioli wrote:
> Hello all,
> I'm trying to graph a scatterplot of a large (5,000 x,y coordinates) of data
> with the caveat that many of the data points overlap with each other (share the
> same x AND y coordinates).  In using the usual "plot" command,
>> plot(education, xlab="etc", ylab="etc")
> it seems that the overlap of points is not shown in the graph.  Namely, there
> are 5,000 points that should be plotted, as I mentioned above, but because so
> many of the points overlap with each other exactly, only about 50-60 points are
> actually plotted on the graph.  Thus, there's no indication that Point A shares
> its coordinates with 200 other pieces of data and thus is very common while
> Point B doesn't share its coordinates with any other pieces of data and thus
> isn't common at all.  Is there anyway to indicate the frequency of such points
> on such a graph?  Should I be using a different command than "plot"?

The jitter() function can add a bit of noise to your data, so that 
repeated points show up as groupings instead of isolated points.

Duncan Murdoch

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