Re: [netcdfgroup] NcML and Enumerated Types - Problem with the syntax

• To: Timothy Patterson <Timothy.Patterson@xxxxxxxxxxxx>, "'netcdfgroup@xxxxxxxxxxxxxxxx'" <netcdfgroup@xxxxxxxxxxxxxxxx>
• Subject: Re: [netcdfgroup] NcML and Enumerated Types - Problem with the syntax
• From: Timothy Patterson <Timothy.Patterson@xxxxxxxxxxxx>
• Date: Thu, 10 Dec 2015 15:00:44 +0100

After downloading Tools UI and playing around a bit, I think I can provide part 
of the answer to my own question.


The element in the example NcML text:

  <variable name="primary_cloud" shape="station" type="enum1">

seems to be need an attribute called "typedef" and should be written:

  <variable name="primary_cloud" shape="station" typedef = "cloud_class_t" 
type="enum1">

The need for the type attribute seems redundant with typedef but leaving out 
the type attribute causes Tool UI to complain.

However, including it but setting it incorrectly, e.g.

  <variable name="primary_cloud" shape="station" typedef = "cloud_class_t" 
type="enum2">

doesn't raise an error.

Regards,

Tim



-----Original Message-----
From: netcdfgroup-bounces@xxxxxxxxxxxxxxxx 
[mailto:netcdfgroup-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Timothy Patterson
Sent: Wednesday, December 09, 2015 7:26 PM
To: 'netcdfgroup@xxxxxxxxxxxxxxxx'
Subject: [netcdfgroup] NcML and Enumerated Types - Problem with the syntax

The Unidata website has some pages on the Annotated Schema for NcML at 
http://www.unidata.ucar.edu/software/thredds/current/netcdf-java/ncml/AnnotatedSchema4.html
 

It give some example NcML code for an enumerated type:

<?xml version="1.0" encoding="UTF-8"?>
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2"; 
location="Q:/cdmUnitTest/formats/netcdf4/tst/test_enum_type.nc">
  <enumTypedef name="cloud_class_t" type="enum1">
    <enum key="0">Clear</enum>
    <enum key="1">Cumulonimbus</enum>
    <enum key="2">Stratus</enum>
    <enum key="3">Stratocumulus</enum>
    <enum key="4">Cumulus</enum>
    <enum key="5">Altostratus</enum>
    <enum key="6">Nimbostratus</enum>
    <enum key="7">Altocumulus</enum>
    <enum key="8">Cirrostratus</enum>
    <enum key="9">Cirrocumulus</enum>
    <enum key="10">Cirrus</enum>
    <enum key="255">Missing</enum>
  </enumTypedef>
  <dimension name="station" length="5" />
  <variable name="primary_cloud" shape="station" type="enum1">
    <attribute name="_FillValue" value="Missing" />
  </variable>
</netcdf>


There seems to me to be a problem, in that the variable definition is set to be 
a type of enum1 and never refers back to the defined type "cloud_class_t".

Indeed, if you read the example into tools UI, it produces this CDL:

netcdf test_enum_type.ncml {
  types:
    byte enum cloud_class_t { 'Clear' = 0, 'Cumulonimbus' = 1, 'Stratus' = 2, 
'Stratocumulus' = 3, 'Cumulus' = 4, 'Altostratus' = 5, 'Nimbostratus' = 6, 
'Altocumulus' = 7, 'Cirrostratus' = 8, 'Cirrocumulus' = 9, 'Cirrus' = 10, 
'Missing' = 255};

  dimensions:
    station = 5;
  variables:
    enum UNKNOWN primary_cloud(station=5);
      :_FillValue = "Missing";

}

I want to be able to create NcML code so that the last lines read:

cloud_class_t primary_cloud(station=5) ;
  :_FillValue = Missing ;

However, changing the definition in the NcML declaration to 

  <variable name="primary_cloud" shape="station" type="cloud_class_t">

causes NcDump to throw an exception instead.

Any insight or help is appreciated as I'd like to be able to use enums in my 
own NcML descriptions.

Thanks!

Tim

_________________________________________________________________________________________
Dr. Tim Patterson
Product Format and Test Data Coordinator Instrument Data Simulation Expert MTG 
Programme GEO  Division

EUMETSAT
Eumetsat-Allee 1
64295 Darmstadt
Germany

Tel: +49 6151 807 487
Fax: +49 6151 807 7
E-mail: timothy.patterson@xxxxxxxxxxxx
Web: www.eumetsat.int




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• References:
  • [netcdfgroup] NcML and Enumerated Types - Problem with the syntax
    • From: Timothy Patterson