[R] Plotting Satellite

Dao_De Zeef at gmx.de
Tue Apr 1 19:23:19 CEST 2014


I want to read the following file with and extract the longitude and latitude
for certain areas. 
The file is satellite data from topex and contains the monthly wave energy
fluxes around the worlds oceans.


For doing that i have the following loop that reads the specific data.

I then want to create a worldmap/the specific region for example the baltic
sea or whatever, that shows the the wave energy. Also i want to plot the
averages and the trend for the wave energy and eventually calcualte a slope
for the wave energy over time.




I got the following loop




library(sp)
library(maptools)
library(maps)
library(rgdal)
library(shape)
library(mapdata)

# "pow_sat_file.txt"

inputpath1<-"/Users/Sam/Desktop/MER/rem/" 
inputfile1<-paste(inputpath1,"pow_sat_file.txt",sep="") 

sat<-read.table("pow_sat_file.txt",header=TRUE, sep="",nrow=-1)
sat.mat<-as.data.frame(sat)

dims<-dim(sat.mat)
tempo<-matrix(0, nrow=dims[1], ncol=dims[2])
tempo<-data.frame(tempo)
date<-seq(as.Date("1993/1/1"), as.Date("2005/10/1"), by="month")

# France coordinates
long.min<--6
long.max<-10
lat.min<-40
lat.max<-52

#Loop on "pow_sat_file.txt" to only keep the interesting points
for (i in 1:dims[1]){
  long<-sat.mat[i,1]
  lat<-sat.mat[i,2]
  if (((long>=-6 && long<=10)==TRUE ) && ((lat>=40 && lat<=52))==TRUE){
    tempo[i,1]<-long
    tempo[i,2]<-lat
    for (j in 3:dims[2]){
      tempo[i,j]<-sat.mat[i,j]
    }
  }
}


How do i continue from here to get a map of the specific region and a slope?

Thx in advance



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