7.5 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 (NetCDF Users Guide).
Errors
NF90_GET_ATT_ type returns the value NF90_NOERR if no errors
occurred. Otherwise, the returned status indicates an error. Possible
causes of errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified attribute does not exist.
- The specified netCDF ID does not refer to an open netCDF dataset.
- One or more of the attribute values are out of the range of values
representable by the desired type.
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)
