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5.5 Get Attribute's Values: NF90_GET_ATT

Function nf90_get_att gets the value(s) of a netCDF attribute, given its variable ID and name.

Usage

      function nf90_get_att(ncid, varid, name, values)
        integer,            intent( in) :: ncid, varid
        character(len = *), intent( in) :: name
        any valid type, scalar or array of rank 1, &
                            intent(out) :: values
        integer                         :: nf90_get_att
ncid
NetCDF ID, from a previous call to NF90_OPEN or NF90_CREATE.
varid
Variable ID of the attribute's variable, or NF90_GLOBAL for a global attribute.
name
Attribute name.
values
Returned attribute values. All elements of the vector of attribute values are returned, so you must provide enough space to hold them. If you don't know how much space to reserve, call NF90_INQUIRE_ATTRIBUTE first to find out the length of the attribute. If there is only a single attribute values may be a scalar. If the attribute is of type character values should be a variable of type character with the len Fortran 90 attribute set to an appropriate value (i.e. character (len = 80) :: values). You cannot read character data from a numeric variable or numeric data from a text variable. For numeric data, if the type of data differs from the netCDF variable type, type conversion will occur. See Type Conversion.

Errors

NF90_GET_ATT returns the value NF90_NOERR if no errors occurred. Otherwise, the returned status indicates an error. Possible causes of errors include:

Example

Here is an example using NF90_GET_ATT to determine the values of an attribute named valid_range for a netCDF variable named rh and a global attribute named title in an existing netCDF dataset named foo.nc. In this example, it is assumed that we don't know how many values will be returned, so we first inquire about the length of the attributes to make sure we have enough space to store them:

      use netcdf
      implicit none
      integer              :: ncid, status
      integer              :: RHVarID                       ! Variable ID
      integer              :: validRangeLength, titleLength ! Attribute lengths
      real, dimension(:), allocatable, &
                           :: validRange
      character (len = 80) :: title
      ...
      status = nf90_open("foo.nc", nf90_nowrite, ncid)
      if (status /= nf90_noerr) call handle_err(status)
      ...
      ! Find the lengths of the attributes
      status = nf90_inq_varid(ncid, "rh", RHVarID)
      if (status /= nf90_noerr) call handle_err(status)
      status = nf90_inquire_attribute(ncid, RHVarID, "valid_range", &
                                len = validRangeLength)
      if (status /= nf90_noerr) call handle_err(status)
      status = nf90_inquire_attribute(ncid, nf90_global, "title", len = titleLength)
      if (status /= nf90_noerr) call handle_err(status)
      ...
      !Allocate space to hold attribute values, check string lengths
      allocate(validRange(validRangeLength), stat = status)
      if(status /= 0 .or. len(title) < titleLength)
        print *, "Not enough space to put attribute values."
        exit
      end if
      ! Read the attributes.
      status = nf90_get_att(ncid, RHVarID, "valid_range", validRange)
      if (status /= nf90_noerr) call handle_err(status)
      status = nf90_get_att(ncid, nf90_global, "title", title)
      if (status /= nf90_noerr) call handle_err(status)