Interpolation/
file_interp.pro
interpolate a NetCDF file from a grid to another (both regular or not)
file_interp
Interpolation and NetCDF
file_interp, filein, fileout, gridout, GRIDIN=scalar string, MASKIN=scalar string, MASKOUT=scalar string, KEEP=string array, REMOVE=string array, METHOD=scalar string, SMOOTH=scalar 0 or 1, SET_XDIMNAME=scalar string, SET_YDIMNAME=scalar string, SET_XAXISNAME=scalar string, SET_YAXISNAME=scalar string, INMASKNAME=scalar string, ININVMASK=scalar: 0 or 1, INUSEASMASK=scalar string, INMISSING_VALUE=scalar, INADDSCL_BEFORE=scalar: 0 or 1, OUTMASKNAME=scalar string, OUTINVMASK=scalar: 0 or 1, OUTUSEASMASK=scalar string, OUTMISSING_VALUE=scalar, OUTADDSCL_BEFORE=scalar: 0 or 1, NAN_VALUE=scalar, WEIG=2d array or variable name, ADDR=2d array or variable name, INXAXISNAME=scalar string, INYAXISNAME=scalar string, OUTXAXISNAME=scalar string, OUTYAXISNAME=scalar string, _EXTRA=_EXTRA
Parameters
filein
in
type: scalar string
input file name (must exist)
fileout
in
type: scalar string
output file name (will be overwritten if already exist)
gridout
in
type: scalar string
output grid file name (must exist and must contain the
longitude and latitude axis as 1D or 2D arrays)
Keywords
GRIDIN
type: scalar string
default: set to filein
define the input grid file name. It must exist and must contain the
longitude and latitude axis as 1D or 2D arrays. Useful if
filein file doesn't contain longitude and latitude axis
MASKIN
type: scalar string
default: set to gridin
define the input mask file name. It must exist. The mask will be
determided through ncdf_getmask according to the keywords
inmaskname, ininvmask, inuseasmask, inmissing_value, inaddscl_before
(see bellow)
MASKOUT
type: scalar string
default: set to gridout
define the output mask file name. It must exist. The mask will be
determided through ncdf_getmask according to the keywords
outmaskname, outinvmask, outuseasmask, outmissing_value,
outaddscl_before (see bellow)
KEEP
type: string array
default: all variables
array defining the name of the variables that must be kept in the
output file
REMOVE
type: string array
default: empty
array defining the name of the variables that will be removed in the
output file
METHOD
type: scalar string
default: 'bilinear'
interpolation method: can be only 'bilinear' (or 'imoms3' if the iput grid
is a "regular" grid). A "regular/rectangular grid" is defined as a
grid for which each longitude lines have the same latitude and each
latitude columns have the same longitude.
SMOOTH
type: scalar 0 or 1
default: 0
activate to use extrapsmooth instead of
extrapolate when extrapolating input data over masked
points.
SET_XDIMNAME
type: scalar string
default: not used
used to defined the name of x dimension in filein input file when
gridin keyword is used and when the x dimension name is not the same
in filein and gridin files. By default, we assume both file have the
same x dimension name.
SET_YDIMNAME
type: scalar string
default: not used
same as set_xdimname but for y dimension
SET_XAXISNAME
type: scalar string
default: not used
used to defined the name of the variable containing the x axis in
filein input file when gridin keyword is used and when its variable
containing the x axis name is not the same. By default, we assume
both file have the same x axis name. Not that if filein includes x
axis ther is no point to use gridin
SET_YAXISNAME
type: scalar string
default: not used
same as set_xaxisname but for y dimension
INMASKNAME
type: scalar string
default: not used
A string giving the name of the variable in the file maskin that
contains the land/sea mask
ININVMASK
type: scalar: 0 or 1
default: 0
Inverse the land/sea mask of the input mask file maskin (that should
have 0/1 values for land/sea)
INUSEASMASK
type: scalar string
A string giving the name of the variable in the input mask file maskin
that will be used to build the land/sea mask. In this case the
mask is based on the first record (if record dimension
exists). The mask is build according to :
1 the keyword missing_value if existing
2 the attribute 'missing_value' if existing
3 NaN values if existing
INMISSING_VALUE
type: scalar
To define (or redefine if the attribute is already existing) the
missing values used by INUSEASMASK keyword
INADDSCL_BEFORE
type: scalar: 0 or 1
default: 0
put 1 to apply add_offset ad scale factor on data before looking for
missing values when using INUSEASMASK keyword
OUTMASKNAME
type: scalar string
default: not used
same as inmaskname but for output mask file maskout
OUTINVMASK
type: scalar: 0 or 1
default: 0
same as ininvmask but for output mask file maskout
OUTUSEASMASK
type: scalar string
same as inuseasmask but for output mask file maskout
OUTMISSING_VALUE
type: scalar
same as inmissing_value but for output mask file maskout
OUTADDSCL_BEFORE
type: scalar: 0 or 1
default: 0
same as inaddscl_before but for output mask file maskout
NAN_VALUE
type: scalar
default: not used
define the missing value in input data (missing values are treated
like masked values and will be filled with extrapolation before
interpolation).
WEIG
type: 2d array or variable name
(see ADDR)
ADDR
type: 2d array or variable name
1) at the first call of file_interp:
This keyword can be set to a named variable (undefined or equal to
0) into which the addresses used to perform the interpolation will
be copied when the current routine exits.
2) Next, once this keyword is set to a defined 2d array, it is used
to bypass the computation of the weights and addresses used to
perform the interpolation. In this case, interpolation is much
faster
INXAXISNAME
type: scalar string
default: 'x', 'longitude', 'nav_lon', 'lon', 'lon_rho' or 'NbLongitudes'
A string giving the name of the variable containning the x axis in
the input grid file gridin
INYAXISNAME
type: scalar string
default: 'y', 'latitude', 'nav_lat','lat', 'lat_rho' or 'NbLatitudes'
same as inxaxisname but for the y axis in the input grid file gridin
OUTXAXISNAME
type: scalar string
default: 'x', 'longitude', 'nav_lon', 'lon', 'lon_rho' or 'NbLongitudes'
same as inxaxisname but for output grid file gridout
OUTYAXISNAME
type: scalar string
default: 'y', 'latitude', 'nav_lat','lat', 'lat_rho' or 'NbLatitudes'
same as inyaxisname but for output grid file gridout
_EXTRA
to use extrapolate, extrapsmooth and fromreg keywords
Examples
IDL> file_interp, filein, fileout, gridout, inxaxisname = 'lo', inyaxisname = 'la', keep = ['lo', 'la', 'cond_sed']
IDL> file_interp, in, out, gdout, inuseasmask = 'sst', inmissing_value = -1.00000e+30, nan_value = -1000.00
Version history
Version
$Id: file_interp.pro 283 2007-09-12 15:45:09Z smasson $
History
September 2007: Sebastien Masson (smasson@locean-ipsl.upmc.fr)
Known issues
Restrictions
- perform only horizontal interpolations on scalar fields
- will fill all masked and missing values before interpolation
- attributes (like valid_min...) are not updated
- see restrictions of fromreg and fromirr
Other attributes
Uses routines
extrapsmooth, extrapolate, fromreg and fromirr
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