Scenario
Create a PDS4 label that describes the data in a CDF file.
Our CDF file contains a time series of data.
It has a magnetic field vector in HDZ coordinates and time stamp for each vector.
The magnetic field vector is stored as a 2D array with the dimension of 3 by 1440.
The time stamp is a 1D array with 1440 elements (one for each HDZ vector).
We want to create an PDS4 label that describes the data in the CDF file.
We will use the data file with the name thg_l2_mag_and_20121226_v01.cdf.
Our velocity template will be a PDS4 label with some information already filled in.
Information specific to the contents of the CDF file (data arrays, record count, file size, etc.) will be generated
using igpp.docgen. Our template looks like:
<![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<Product_Observational xmlns="http://pds.nasa.gov/pds4/pds/v1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="PDS4_PDS_1000.xsd">
<Identification_Area>
<logical_identifier>urn:nasa:pds:themis:fgm:$cdf.getAttributeValue('Logical_file_id')::v0$cdf.getAttributeValue('Data_version')</logical_identifier>
<version_id>1.0</version_id>
<title>$cdf.getAttributeValue('Logical_source_description')</title>
<information_model_version>1.1.0.0</information_model_version>
<product_class>Product_Observational</product_class>
</Identification_Area>
<Observation_Area>
<Time_Coordinates>
<start_date_time>Unknown</start_date_time>
<stop_date_time>Unknown</stop_date_time>
</Time_Coordinates>
<Primary_Result_Summary>
<purpose>Science</purpose>
<data_regime>Magnetopshere</data_regime>
<processing_level_id>Calibrated</processing_level_id>
</Primary_Result_Summary>
<Investigation_Area>
<name>$cdf.getAttributeValue("Mission_group") $cdf.getAttributeValue("TITLE")</name>
<type>Observing Campaign</type>
<Internal_Reference>
<lid_reference>urn:nasa:pds:themis:fgm</lid_reference>
<reference_type>data_to_investigation</reference_type>
</Internal_Reference>
</Investigation_Area>
<Observing_System>
<Observing_System_Component>
<name>THEMIS-A</name>
<type>Spacecraft</type>
</Observing_System_Component>
</Observing_System>
<Target_Identification>
<name>Earth</name>
<type>WhoKnows</type>
</Target_Identification>
</Observation_Area>
<File_Area_Observational>
<File>
<file_name>$cdf.pathName</file_name>
</File>
<Header>
<name>CDF Header</name>
<offset unit="byte">0</offset>
<object_length unit="byte">404</object_length>
<parsing_standard_id>CDF 3.4 ISTP/IACG</parsing_standard_id>
</Header>
#foreach ($variable in $cdf.variables)
#set($var_type = $variable.getAttributeValue("VAR_TYPE"))
#set($funct = $variable.getAttributeValue("FUNCT"))
#if( ! $funct.isEmpty() || $var_type.compareTo("metadata") == 0)
## Don't output functions or metadata
#else
#if($variable.getDimCount() == 1)
#if($variable.getDim(0) == 1)
#set($arrayTag="Array_1D")
#set($axis=1)
#else
#set($arrayTag="Array_2D")
#set($axis=2)
#{end}## dim()
#{end}## dimCount()
<$arrayTag>
<name>$variable.getAttributeValue('FIELDNAM')</name>
<local_identifier>$variable.name</local_identifier>
<offset unit="byte">$variable.startByte</offset>
<axes>$axis</axes>
<axis_index_order>#foreach($a in [1..$axis])$a #end</axis_index_order>
<description>$variable.getAttributeValue("CATDESC")
$variable.getAttributeValue("VAR_NOTES") </description>
<Element_Array>
<data_type>$cdf.getDataTypePDS($variable.dataType)</data_type>
</Element_Array>
#foreach($a in [1..$axis])
#set($i = $a - 2) ## CDF indexing of dims does not include rows dimension and indexing starts at 0.
<Axis_Array>
#if($a == 1)
<axis_name>Record</axis_name>
<elements>$variable.recordCount</elements>
#else
<axis_name>$variable.name</axis_name>
<elements>$variable.getDim($i)</elements>
#{end}## if $a == 1
<sequence_number>$a</sequence_number>
</Axis_Array>
#{end}## foreach($a)
</$arrayTag>
#{end}## If data or func
#{end}## foreach variable
</File_Area_Observational>
</Product_Observational>
]]>
We will store this in a file called pds4label.vm.
A CDF file contains attributes and variables. An attribute can contain descriptive information
which is transferred into the appropriate PDS4 element. A varaible can contain data or sets of metadata
In the template conditional statements (if/else) make sure that we only write the variables
in the CDF file which are designated as "data".
Running igpp.docgen with the command:
java -jar igpp-docgen.jar cdf:thg_l2_mag_and_20121226_v01.cdf testcase/cdf/pds4label.vm
Instructs igpp.docgen to parse the file "thg_l2_mag_and_20121226_v01.cdf" and place the results in a context
named "cdf". Since the extension on "thg_l2_mag_and_20121226_v01.cdf" is ".cdf" igpp.docgen will parse the
file a CDF file, creating arrays to contian the attribute and variable information in the file.
Running this command will generate an XML document that looks like:
<![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<Product_Observational xmlns="http://pds.nasa.gov/pds4/pds/v1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://pds.nasa.gov/pds4/pds/v1 file:PDS4_PDS_1000.xsd">
<Identification_Area>
<logical_identifier>urn:nasa:pds:themis:fgm:thg_l2_mag_and_20121226_v01::v01</logical_identifier>
<version_id>1.0</version_id>
<title>Ground-based Vector Magnetic Field at Andenes, Norway, 1 minute time Resolution.</title>
<information_model_version>1.1.0.0</information_model_version>
<product_class>Product_Observational</product_class>
</Identification_Area>
<Observation_Area>
<Time_Coordinates>
<start_date_time>Unknown</start_date_time>
<stop_date_time>Unknown</stop_date_time>
</Time_Coordinates>
<Primary_Result_Summary>
<purpose>Science</purpose>
<data_regime>Magnetopshere</data_regime>
<processing_level_id>Calibrated</processing_level_id>
</Primary_Result_Summary>
<Investigation_Area>
<name>THEMIS</name>
<type>Observing Campaign</type>
<Internal_Reference>
<lid_reference>urn:nasa:pds:themis:fgm</lid_reference>
<reference_type>data_to_investigation</reference_type>
</Internal_Reference>
</Investigation_Area>
<Observing_System>
<Observing_System_Component>
<name>THEMIS-A</name>
<type>Spacecraft</type>
</Observing_System_Component>
</Observing_System>
<Target_Identification>
<name>Earth</name>
<type>WhoKnows</type>
</Target_Identification>
</Observation_Area>
<File_Area_Observational>
<File>
<file_name>thg_l2_mag_and_20121226_v01.cdf</file_name>
</File>
<Header>
<name>CDF Header</name>
<offset unit="byte">0</offset>
<object_length unit="byte">404</object_length>
<parsing_standard_id>CDF 3.4 ISTP/IACG</parsing_standard_id>
</Header>
<Array_2D>
<name>B in HDZ Components</name>
<local_identifier>thg_mag_and</local_identifier>
<offset unit="byte">20031</offset>
<axes>2</axes>
<axis_index_order>1 2</axis_index_order>
<description>Magnetic field B in HDZ vector components
Rotated from geographic XYZ components using declination provided by TGU.</description>
<Element_Array>
<data_type>IEEE754MSBSingle</data_type>
</Element_Array>
<Axis_Array>
<axis_name>Record</axis_name>
<elements>1440</elements>
<sequence_number>1</sequence_number>
</Axis_Array>
<Axis_Array>
<axis_name>thg_mag_and</axis_name>
<elements>3</elements>
<sequence_number>2</sequence_number>
</Axis_Array>
</Array_2D>
<Array_2D>
<name>HDZ Component Number</name>
<local_identifier>thg_mag_and_compno</local_identifier>
<offset unit="byte">40541</offset>
<axes>2</axes>
<axis_index_order>1 2</axis_index_order>
<description>HDZ Component Number</description>
<Element_Array>
<data_type>SignedMSB4</data_type>
</Element_Array>
<Axis_Array>
<axis_name>Record</axis_name>
<elements>1</elements>
<sequence_number>1</sequence_number>
</Axis_Array>
<Axis_Array>
<axis_name>thg_mag_and_compno</axis_name>
<elements>3</elements>
<sequence_number>2</sequence_number>
</Axis_Array>
</Array_2D>
<Array_1D>
<name>thg_mag_and_time</name>
<local_identifier>thg_mag_and_time</local_identifier>
<offset unit="byte">42468</offset>
<axes>1</axes>
<axis_index_order>1</axis_index_order>
<description>thg_mag_and_time,.UTC, in seconds since 01-Jan-1970 00:00:00
Unleaped seconds</description>
<Element_Array>
<data_type>IEEE754MSBDouble</data_type>
</Element_Array>
<Axis_Array>
<axis_name>Record</axis_name>
<elements>1440</elements>
<sequence_number>1</sequence_number>
</Axis_Array>
</Array_1D>
<Array_1D>
<name>thg_mag_and_epoch0</name>
<local_identifier>thg_mag_and_epoch0</local_identifier>
<offset unit="byte">57492</offset>
<axes>1</axes>
<axis_index_order>1</axis_index_order>
<description>EPOCH0 of THEMIS TIME BASE
EPOCH of 01-Jan-1970 00:00:00</description>
<Element_Array>
<data_type>IEEE754MSBDouble</data_type>
</Element_Array>
<Axis_Array>
<axis_name>Record</axis_name>
<elements>1</elements>
<sequence_number>1</sequence_number>
</Axis_Array>
</Array_1D>
<Array_1D>
<name>range_epoch</name>
<local_identifier>range_epoch</local_identifier>
<offset unit="byte">58508</offset>
<axes>1</axes>
<axis_index_order>1</axis_index_order>
<description>range_epoch</description>
<Element_Array>
<data_type>IEEE754MSBDouble</data_type>
</Element_Array>
<Axis_Array>
<axis_name>Record</axis_name>
<elements>2</elements>
<sequence_number>1</sequence_number>
</Axis_Array>
</Array_1D>
</File_Area_Observational>
</Product_Observational>
]]>