/// <summary>
///
/// </summary>
/// <param name="varId"></param>
/// <param name="attributeName"></param>
/// <returns>null when attribute does not exist</returns>
private NetCdfAttribute GetAttribute(int varId, string attributeName)
{
NetCdfDataType type;
IntPtr lengthPtr;
var status = NetCdfWrapper.nc_inq_att(id, varId, attributeName, out type, out lengthPtr);
int length = lengthPtr.ToInt32();
if (status == (int)NetCdfWrapper.ResultCode.NC_ENOTATT)
{
return(null);
}
CheckResult(status);
switch (type)
{
case NetCdfDataType.NC_CHAR:
var charArray = new byte[length + 1];
IntPtr ptr = UTF8Marshal.BytesUTF8ToPtr(charArray);
CheckResult(NetCdfWrapper.nc_get_att_text(id, varId, attributeName, ptr));
charArray[length] = 0;
return(new NetCdfAttribute(attributeName, UTF8Marshal.PtrToStringUTF8(ptr)));
case NetCdfDataType.NC_INT:
var intArray = new int[length];
CheckResult(NetCdfWrapper.nc_get_att_int(id, varId, attributeName, intArray));
return(new NetCdfAttribute(attributeName, intArray[0]));
case NetCdfDataType.NC_FLOAT:
var floatArray = new float[length];
CheckResult(NetCdfWrapper.nc_get_att_float(id, varId, attributeName, floatArray));
return(new NetCdfAttribute(attributeName, floatArray[0]));
case NetCdfDataType.NC_DOUBLE:
var doubleArray = new double[length];
CheckResult(NetCdfWrapper.nc_get_att_double(id, varId, attributeName, doubleArray));
return(new NetCdfAttribute(attributeName, doubleArray[0]));
default:
throw new Exception(
String.Format("Unknown type {0} for reading NetCDF attribute {1} from file {2}",
type, attributeName, path));
}
}