[R-sig-Geo] problem in reading NC file and plot it

[tony333]

at first i use NCEP/NCAR Reanalysis Monthly Means  of Sea level pressure 
my script 

#rm(list=ls()) 



library(ncdf) 
library(maps) 
library(fields) 


### directory that contains slp data 
datadir = '/home/tony/slp.mon.mean.nc' 


### get lat-lon coordinates from first file, then close the file 
slp.nc = open.ncdf(datadir) 
lonall = get.var.ncdf(slp.nc,'lon') 
latall = get.var.ncdf(slp.nc,'lat') 
timall = get.var.ncdf(slp.nc,'time') 
close(slp.nc) 

#### specify domain 
lonmin = 0 
lonmax = 357.5 
latmin = -90 
latmax =  90 

piclon = lonmin <= lonall & lonall <= lonmax 
piclat = latmin <= latall & latall <= latmax 
lon = lonall[piclon] 
lat = latall[piclat] 
nlon = length(lon) 
nlat = length(lat) 
# if extra months exist, only take months that account for entire year 
slp.nmonths = floor(length(timall)/12)*12 
slp.nyrs = slp.nmonths/12 

slp.clim <- array(NA,dim=c(nlon,nlat,12)) 

################## read data ################################# 
slp.nc = open.ncdf(datadir) 
dum = get.var.ncdf(slp.nc,"slp") 
slp.all = dum[piclon,piclat,1:slp.nmonths] 
dim(slp.all) = c(nlon,nlat,12,slp.nyrs) 
close(slp.nc) 



dim(slp.all) = c(nlon*nlat,12,slp.nyrs) 
dim(slp.clim) = c(nlon*nlat,12) 
for (month in 1:12) { 
   slp.clim[,month] = rowMeans(slp.all[,month,]) 
  slp.all[,month,] = slp.all[,month,] - slp.clim[,month] 
   } 
dim(slp.all) = c(nlon,nlat,12,slp.nyrs) 
dim(slp.clim) = c(nlon,nlat,12) 
########################################################## 
############## plot slp anamoly shaded  ############################# 
image.plot(lon,lat,slp.all[,,5,1]) 
map('world2',interior=FALSE,add=T) 
############################################ 
that is the script i use the error is (Error in image.default(..., add =
add, col = col) : 
  increasing 'x' and 'y' values expected) 
and if i use      image.plot(lon,-lat,slp.all[,,5,1]) 
with negative sign in frant of lat it plot but inverse figure the lat is
arranged from +90 to -90 and i do not know if that 
due to sequence in R from negative to positive or not thanks alot for help

--
View this message in context: http://r-sig-geo.2731867.n2.nabble.com/problem-in-reading-NC-file-and-plot-it-tp7150538p7150538.html
Sent from the R-sig-geo mailing list archive at Nabble.com.