R help - Mar 2012 - How do I do a pretty scatter plot using ggplot2?

Hi all,

I am trying hard to do the following and have already spent a few hours in
vain:

I wanted to do the scatter plot.

But given the high dispersion on those dots, I would like to bin the x-axis
and then for each bin of the x-axis, plot the quantiles of the y-values of
the data points in each bin:

1. Uniform bin size on the x-axis;
2. Equal number of observations in each bin;

How to do that in R? I guess for the sake of prettyness, I'd better do it
in ggplot2?

Thank you!

	[[alternative HTML version deleted]]

Hi Michael,

Although I do think ggplot2 does a superb job of elegant data
visualization; I am not sure any graphics package will do what you
want.  I suspect you will first have to do some work binning your
data, and then plot in your package of choice.

In the situation that you have described, I do not believe your two
criteria can be met.  Having x bins of equal size seems prohibitive of
having equal number of points in each, when values are highly
dispersed.

Just as a heads up, for this specific of a task, I would expect you
will spend a few hours more than you already have.  If you are willing
to be a bit more flexible in your requirements, there are various
binning algorithms in ggplot2 and other packages you could use to bin
x valus, and then plot those against y quantiles.

You are more likely to get a clear answer from the list if you can
provide some sample data and perhaps a few example graphs showing what
you hope to achieve.  An easy way to provide some sample data is using
the dput() function and then paste the output into your (plaintext
please) email).

Cheers,

Josh

On Fri, Mar 9, 2012 at 4:37 PM, Michael <comtech.usa at gmail.com>
wrote:
> Hi all,
>
> I am trying hard to do the following and have already spent a few hours in
> vain:
>
> I wanted to do the scatter plot.
>
> But given the high dispersion on those dots, I would like to bin the x-axis
> and then for each bin of the x-axis, plot the quantiles of the y-values of
> the data points in each bin:
>
> 1. Uniform bin size on the x-axis;
> 2. Equal number of observations in each bin;
>
> How to do that in R? I guess for the sake of prettyness, I'd better do
it
> in ggplot2?
>
> Thank you!
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


-- 
Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, Statistical Consulting Group
University of California, Los Angeles
https://joshuawiley.com/

That doesn't really seem to make sense to me as a graphical
representation (transforming adjacent y values differently), but if
you really want to do so, here's what I'd do if I understand your goal
(the preprocessing is independent of the graphics engine):

DAT <- data.frame(x = runif(1000, 0, 20), y = rcauchy(1000)^2) # Nice
and volatile!

# split y based on some x binning and assign empirical quantiles of each group

DAT$yquant <- with(DAT, ave(y, cut(x, seq(0, 20, 5)), FUN function(x)
ecdf(x)(x)))

# BASE
plot(yquant ~ x, data = DAT)

 # ggplot2
library(ggplot2)

p <- ggplot(DAT, aes(x = x, y = yquant)) + geom_point()
print(p)

Michael Weylandt

PS -- I see Josh Wiley just responded pointing out your requirements
#1 and #2 are incompatible: I've used 1 here.

On Fri, Mar 9, 2012 at 7:37 PM, Michael <comtech.usa at gmail.com>
wrote:
> Hi all,
>
> I am trying hard to do the following and have already spent a few hours in
> vain:
>
> I wanted to do the scatter plot.
>
> But given the high dispersion on those dots, I would like to bin the x-axis
> and then for each bin of the x-axis, plot the quantiles of the y-values of
> the data points in each bin:
>
> 1. Uniform bin size on the x-axis;
> 2. Equal number of observations in each bin;
>
> How to do that in R? I guess for the sake of prettyness, I'd better do
it
> in ggplot2?
>
> Thank you!
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

On 03/10/2012 11:37 AM, Michael wrote:
> Hi all,
>
> I am trying hard to do the following and have already spent a few hours in
> vain:
>
> I wanted to do the scatter plot.
>
> But given the high dispersion on those dots, I would like to bin the x-axis
> and then for each bin of the x-axis, plot the quantiles of the y-values of
> the data points in each bin:
>
> 1. Uniform bin size on the x-axis;
> 2. Equal number of observations in each bin;
>
> How to do that in R? I guess for the sake of prettyness, I'd better do
it
> in ggplot2?
>
Hi Michael,
While it is not in ggplot2, a variation on the count.overplot function 
might do what you want. This function displays counts of closely spaced 
points rather than the points, but it applies the same area of 
aggregation across the whole plot. Getting the equal x bins is easy, and 
I assume that you mean equal observations within each bin, not across 
all bins. If you are stuck, I can probably hack up something from 
count.overplot.

Jim