Hi all
I am a newbi to IDL. Am trying to find wind trajectory using nearest
grid point. Am using NCEP data file air.2000.nc which consists of lon,
lat, level, and time. But am getting error which is not reachable to
me. Please help me on this. Code & error iare as follows:
pro ngp,fid,posx,nx,posy,ny,posz,nz, $
AVERAGE=average,WRAPAROUND=wraparound,NO_MESSAGE=no_message
filepath='/home2/shambhu/'
filename=dialog_pickfile(path=filepath)
fid=ncdf_open(filename)
;print,'file id is: ',fid
fileinq_struct=ncdf_inquire(fid)
nvars=fileinq_struct.nvars
;print,'variables in file: ',nvars
for varndx=0,nvars-1 do begin $
varstruct=ncdf_varinq(fid,varndx)
for attndx=0,varstruct.natts-1 do begin $
attname=ncdf_attname(fid,varndx,attndx)
ncdf_attget,fid,varndx,attname,fid
;print,attname,string(fid)
posx=string(fid)
;print,'posx:' , posx
;print,'Var Name:',
varstruct.name,' ',varstruct.datatype,' ',varstruct.dim
endfor
endfor
nrsamples=n_elements(fid)
nparams=n_params()
print,nparams
print,'nparams: ',nparams
dim=(nparams-1)/2
print,'dim: ',dim
IF dim LE 2 THEN BEGIN
nz=1
print,'nz: ',nz
IF dim EQ 1 THEN ny=1
ENDIF
read,'Enter value for nx',nx
read,'Enter value for ny',ny
nxny = long(nx)*long(ny)
print,'nxny: ',nxny
; Some error handling.
on_error,2 ; Return to caller if an error occurs.
print,'IF loop'
IF NOT (nparams EQ 3 OR nparams EQ 5 OR nparams EQ 7) THEN BEGIN
message,'Incorrect number of arguments!',/continue
message,'Syntax: NGP, VALUE, POSX, NX[, POSY, NY, POSZ, NZ,' + $
' /AVERAGE, /WRAPAROUND, /NO_MESSAGE]'
ENDIF
IF (nrsamples NE n_elements(posx)) OR $
(dim GE 2 AND nrsamples NE n_elements(posy)) OR $
(dim EQ 3 AND nrsamples NE n_elements(posz)) THEN $
message,'Input arrays must have the same dimensions!'
IF NOT keyword_set(no_message) THEN $
print,'Interpolating ' + strtrim(string(nrsamples,format='(i10)'),1)
$
+ ' samples to ' + strtrim(string(nxny*nz,format='(i10)'),1) + $
' grid points using NGP...'
; Compute nearest grid points.
IF keyword_set(wraparound) THEN BEGIN
; Coordinates of nearest grid point (ngp).
ngx=fix(posx+0.5)
; Periodic boundary conditions.
bad=where(ngx EQ nx,count)
IF count NE 0 THEN ngx[bad]=0
IF dim GE 2 THEN BEGIN
ngy=fix(posy+0.5)
bad=where(ngy EQ ny,count)
IF count NE 0 THEN ngy[bad]=0
IF dim EQ 3 THEN BEGIN
ngz=fix(posz+0.5)
bad=where(ngz EQ nz,count)
IF count NE 0 THEN ngz[bad]=0
ENDIF
ENDIF
bad=0 ; Free memory.
ENDIF ELSE BEGIN
; Coordinates of nearest grid point (ngp).
ngx=fix(posx)
IF dim GE 2 THEN BEGIN
ngy=fix(posy)
IF dim EQ 3 THEN ngz=fix(posz)
ENDIF
ENDELSE
; Indices of grid points to which samples are assigned.
CASE dim OF
1: index=temporary(ngx)
2: index=temporary(ngx)+temporary(ngy)*nx
3: index=temporary(ngx)+temporary(ngy)*nx+temporary(ngz)*nxny
ENDCASE
; Interpolate samples to grid.
field=fltarr(nx,ny,nz)
FOR i=0l,nrsamples-1l DO field[index[i]]=field[index[i]]+value[i]
; Compute weighted average.
IF keyword_set(average) THEN BEGIN
; Number of samples per grid point.
frequency=histogram(temporary(index),min=0,max=nxny*nz-1l)
; Normalize.
good=where(frequency NE 0,nrgood)
field[good]=temporary(field[good])/temporary(frequency[good] )
ENDIF
print,field
close,value
END ; End of function ngp.
Error: NCDF_ATTNAME: Expression must be a scalar in this context: FID.
% Execution halted at: NGP 17 /home2/shambhu/ngp.pro
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
