The NF_GET_VARM_ type family of functions reads a mapped array section of values from a netCDF variable of an open netCDF dataset. The mapped array section is specified by giving a corner, a vector of edge lengths, a stride vector, and an index mapping vector. The index mapping vector is a vector of integers that specifies the mapping between the dimensions of a netCDF variable and the in-memory structure of the internal data array. No assumptions are made about the ordering or length of the dimensions of the data array. The netCDF dataset must be in data mode.
INTEGER FUNCTION NF_GET_VARM_TEXT (INTEGER NCID, INTEGER VARID, INTEGER START(*), INTEGER COUNT(*), INTEGER STRIDE(*), INTEGER IMAP(*), CHARACTER*(*) text) INTEGER FUNCTION NF_GET_VARM_INT1 (INTEGER NCID, INTEGER VARID, INTEGER START(*), INTEGER COUNT(*), INTEGER STRIDE(*), INTEGER IMAP(*), INTEGER*1 i1vals(*)) INTEGER FUNCTION NF_GET_VARM_INT2 (INTEGER NCID, INTEGER VARID, INTEGER START(*), INTEGER COUNT(*), INTEGER STRIDE(*), INTEGER IMAP(*), INTEGER*2 i2vals(*)) INTEGER FUNCTION NF_GET_VARM_INT (INTEGER NCID, INTEGER VARID, INTEGER START(*), INTEGER COUNT(*), INTEGER STRIDE(*), INTEGER IMAP(*), INTEGER ivals(*)) INTEGER FUNCTION NF_GET_VARM_REAL (INTEGER NCID, INTEGER VARID, INTEGER START(*), INTEGER COUNT(*), INTEGER STRIDE(*), INTEGER IMAP(*), REAL rvals(*)) INTEGER FUNCTION NF_GET_VARM_DOUBLE(INTEGER NCID, INTEGER VARID, INTEGER START(*), INTEGER COUNT(*), INTEGER STRIDE(*), INTEGER IMAP(*), DOUBLE dvals(*))
NCID
VARID
START
COUNT
STRIDE
IMAP
text
i1vals
i2vals
ivals
rvals
dvals
NF_GET_VARM_ type returns the value NF_NOERR if no errors occurred. Otherwise, the returned status indicates an error. Possible causes of errors include:
The following IMAP vector maps in the trivial way a 2x3x4 netCDF variable and an internal array of the same shape:
REAL A(2,3,4) ! same shape as netCDF variable INTEGER IMAP(3) DATA IMAP /1, 2, 6/ ! netCDF dimension inter-element distance ! ---------------- ---------------------- ! most rapidly varying 1 ! intermediate 2 (=IMAP(1)*2) ! most slowly varying 6 (=IMAP(2)*3)
Using the IMAP vector above with NF_GET_VARM_REAL obtains the same result as simply using NF_GET_VAR_REAL.
Here is an example of using NF_GET_VARM_REAL to transpose a netCDF variable named rh which is described by the FORTRAN declaration REAL RH(4,6) (note the size and order of the dimensions):
INCLUDE 'netcdf.inc' ... PARAMETER (NDIM=2) ! rank of netCDF variable INTEGER NCID ! netCDF dataset ID INTEGER STATUS ! return code INTEGER RHID ! variable ID INTEGER START(NDIM) ! netCDF variable start point INTEGER COUNT(NDIM) ! size of internal array INTEGER STRIDE(NDIM) ! netCDF variable subsampling intervals INTEGER IMAP(NDIM) ! internal array inter-element distances REAL RH(6,4) ! note transposition of netCDF variable dimensions DATA START /1, 1/ ! start at first netCDF variable element DATA COUNT /4, 6/ ! entire netCDF variable; order corresponds ! to netCDF variable -- not internal array DATA STRIDE /1, 1/ ! sample every netCDF element DATA IMAP /6, 1/ ! would be /1, 4/ if not transposing ... STATUS = NF_OPEN('foo.nc', NF_NOWRITE, NCID) IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS) ... STATUS = NF_INQ_VARID(NCID, 'rh', RHID) IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS) ... STATUS = NF_GET_VARM_REAL(NCID, RHID, START, COUNT, STRIDE, IMAP, RH) IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
Here is another example of using NF_GET_VARM_REAL to simultaneously transpose and subsample the same netCDF variable, by accessing every other point of the netCDF variable:
INCLUDE 'netcdf.inc' ... PARAMETER (NDIM=2) ! rank of netCDF variable INTEGER NCID ! netCDF dataset ID INTEGER STATUS ! return code INTEGER RHID ! variable ID INTEGER START(NDIM) ! netCDF variable start point INTEGER COUNT(NDIM) ! size of internal array INTEGER STRIDE(NDIM) ! netCDF variable subsampling intervals INTEGER IMAP(NDIM) ! internal array inter-element distances REAL RH(3,2) ! note transposition of (subsampled) dimensions DATA START /1, 1/ ! start at first netCDF variable value DATA COUNT /2, 3/ ! order of (subsampled) dimensions corresponds ! to netCDF variable -- not internal array DATA STRIDE /2, 2/ ! sample every other netCDF element DATA IMAP /3, 1/ ! would be `1, 2' if not transposing ... STATUS = NF_OPEN('foo.nc', NF_NOWRITE, NCID) IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS) ... STATUS = NF_INQ_VARID(NCID, 'rh', RHID) IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS) ... STATUS = NF_GET_VARM_REAL(NCID, RHID, START, COUNT, STRIDE, IMAP, RH) IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)