[R] Heatmap in R and/or ggplot2

[JiHO]

On Tue, Jun 14, 2011 at 19:56, idris <idris.raja at gmail.com> wrote:
> Follow up question: My data contains x, y, height, and day.
>
> I want to create the heatmap for each day, keeping the color coding
> consistent.
>
> I've created an example with 2 days, and you can see the charts below.
>
> Notice that the legend changes from day 1 to day 2. How can I make the
> legend consistent?
>
> Also, my real data contains hundreds of days. Is there a way to create a
> 'movie' or a sequence of the heatmaps in chronological order of days?
>
> The way my code works now is obviously very naive as it just repeats the
> same code for day 1 and day 2. Is there a better way to do this?

legend: use the "limit" argument of scale_fill_gradientn and set it to
the max and min of height across all days

movie: there is no way to do that in R alone (that I know of). you can:
1- use the jpeg or png device with a name including a special code
which increases every time a new plot is produced (this is the
default)
2- plot the successive plots in a for loop
3- turn the sequence of images into a movie using  specialized software.

For step 3 you could use guicktime on Mac OS X or mencoder on Linux/OS
X. I don't know about Windows.

Since mencoder works on the command line, you can call it from R and I
have code to ease that:
    https://gitorious.org/r/r-utils/blobs/master/lib_movie.R
but you should get familiar with mencoder a little bit before trying
to read/understand it.

JiHO
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