R help - Oct 2007 - How to add legend for image()?

Dear friends,
   The following is an example to explain my question. I want to get a
legend which will show the z-values according to different colors in image()
function.

x<-sort(runif(10))  #x-coordinates
y<-sort(runif(10))  #y-coordinates
z<-matrix(runif(100),nrow=10)  #attributes values
image(x,y,z,col=gray((6:3)/6))
# legend(x,y,legend=z,col=gray((6:3)/6)) #error. the colors should denote
different z-values, i want to get this legend.

 Thanks.

-- 
With Kind Regards,

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[***********************************************************************]
Zhi Jie,Zhang ,PHD
Tel:86-21-54237149
Dept. of Epidemiology,School of Public Health,Fudan University
Address:No. 138 Yi Xue Yuan Road,Shanghai,China
Postcode:200032
Email:epistat@gmail.com
Website: www.statABC.com
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	[[alternative HTML version deleted]]

Have you tried filled.contour()? It automatically generates a legend.
However, I'm not sure what is going on with your x's and y's being
sorted random numbers. I assume your actual data are not like this. If
you do not have data in an equally spaced grid you may need to create
one by some sort of interpolation (e.g. Kriging or inverse distance
weighting).



On 10/2/07, zhijie zhang <epistat at gmail.com>
wrote:
> Dear friends,
>    The following is an example to explain my question. I want to get a
> legend which will show the z-values according to different colors in
image()
> function.
>
> x<-sort(runif(10))  #x-coordinates
> y<-sort(runif(10))  #y-coordinates
> z<-matrix(runif(100),nrow=10)  #attributes values
> image(x,y,z,col=gray((6:3)/6))
> # legend(x,y,legend=z,col=gray((6:3)/6)) #error. the colors should denote
> different z-values, i want to get this legend.
>
>  Thanks.
>
> --
> With Kind Regards,
>
> oooO:::::::::
> (..):::::::::
> :\.(:::Oooo::
> ::\_)::(..)::
> :::::::)./:::
> ::::::(_/::::
> :::::::::::::
> [***********************************************************************]
> Zhi Jie,Zhang ,PHD
> Tel:86-21-54237149
> Dept. of Epidemiology,School of Public Health,Fudan University
> Address:No. 138 Yi Xue Yuan Road,Shanghai,China
> Postcode:200032
> Email:epistat at gmail.com
> Website: www.statABC.com
> [***********************************************************************]
> oooO:::::::::
> (..):::::::::
> :\.(:::Oooo::
> ::\_)::(..)::
> :::::::)./:::
> ::::::(_/::::
> :::::::::::::
>
>         [[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.
>

zhijie zhang wrote:
> Dear friends,
>    The following is an example to explain my question. I want to get a
> legend which will show the z-values according to different colors in
image()
> function.
> 
> x<-sort(runif(10))  #x-coordinates
> y<-sort(runif(10))  #y-coordinates
> z<-matrix(runif(100),nrow=10)  #attributes values
> image(x,y,z,col=gray((6:3)/6))
> # legend(x,y,legend=z,col=gray((6:3)/6)) #error. the colors should denote
> different z-values, i want to get this legend.
> 
Hi Zhijie,
Have a look at color.legend and color.scale in the plotrix package.

Jim