[R] Bubble plot on shapefile - projection issues?

[Roy Mendelssohn]

Use the "bubble" command in gstat.

-Roy M.
On Jan 9, 2009, at 5:58 PM, t c wrote:

> Dear R help list,
>
> I am working on some data from a study on the habitat use and  
> movement patterns of fish using a marine protected area in Hawaii.   
> We have a number of acoustic receivers in a MPA, and any time a  
> tagged fish passes within range it records the date and time of  
> detection.  I am trying to make bubble plots showing the number of  
> detections for each fish at each receiver.  I have been able to get  
> it to work using a map generated from GSHHS data (Global Self- 
> consistent, Hierarchical, Highresolution Shoreline) but the map data  
> is not of high enough resolution.  Instead I am trying to plot the  
> data on a shapefile, but I can't find out how to project the  
> shapefile correctly to match up with the data.  I know my shapefile  
> is in NAD 1983 UTM Zone 4N and my data is in WSG84.  How do I change  
> the projections to make them line up?  I tried mapproj but couldn't  
> get it to work.  Any suggestions would be greatly appreciated.
>
> My code is below.  I have also attached the shapefile and my data.
>
> Thanks in advance for your help.
>
> Aloha,
>
> Tim
>
>
>
>
> #Read ESRI shapefiles
> library(maptools)
> library (PBSmapping)
> setwd("E:/Telemetry_research/Kealakekua Bay MPA study/R bubble plot")
> hawaii.coast<- read.shape("coast_n83.shp")
>
> #Read data and convert to event data
>  mydat<-read.table("my.event", header=TRUE)
>  my.event<-as.EventData(mydat,projection="LL")
>
> #Calculate bubble size
>  detects<-mydat$Detections
>  max.symbol.size=10
>  min.symbol.size=1
>  bubble.size <- (detects-min(detects))/((max(detects)+.0001)- 
> min(detects))*(max.symbol.size-min.symbol.size)+min.symbol.size       
> #Calculates bubble size as a range between min and max.  0.0001  
> added to avoid division by zero if only one sample.
>
> #Plot of all Hawaiii showing point data somewhere to the south.   
> Needs projcting?
> plot(hawaii.coast,xlab="Longitude",ylab="Latitude",main="Kealakekua  
> Bay")
> addPoints(my.event, pch=19 ,col="red",cex=500)
>
>
>
> #Plot of location where point data should be
> plot(hawaii.coast,xlim=c(820000, 824000), ylim=c(2154000,  
> 2158000),xlab="Longitude",ylab="Latitude",main="Kealakekua Bay")
>
>
>
> < 
> my.event><coast_n83.prj>______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

**********************
"The contents of this message do not reflect any position of the U.S.  
Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097

e-mail: Roy.Mendelssohn at noaa.gov (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/

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