R033 Member Extract Production

Outline

Extracts a member of a struct or an array, identified by the member name or id/index and creates a new signal of a given signal type.

Platforms:

32/64bit

Requirements:

None

Known limitations:

None

Status:

Stable

Input signals:

1 Array or Struct signal.

Output signal:

Integer, Float, Text or Event(Enumneration) or Binary: Creates a signal with the member content only.

Parameters:

Process type: Process type of the resulting signal.
Signal type: Signal type of the resulting signal.
Signal descriptor: Signal descriptor of the resulting signal.
Domain base: Domain base of the resulting signal.
Domain range: Domain range of the resulting signal.
Member: Select the member name or id/index.
Keep tags: The output samples shall keep the tag information of each input sample.
Ignore 'None' samples: Ignore 'None' samples of the input signal.
Hide identical: Check to hide sequence of identical samples.

Operation:

Input Signal Configuration

The production accepts 1 Array (IntegerArray,EventArray,FloatArray,TextArray) or Struct signal.

Primary Source: The primary source is the first source signal of the production.

Output Signal Configuration

Productions are executed on the fly, as soon as the signal data is required for further processing, and re-executed when settings or input signal have been changed. Before executing a production, the system needs to know the source signals, the type and the domain of the signal. All these informations need to be entered into the plot configuration dialog. If you leave the configuration fields empty, impulse tries to extract the information from the sources. The fields will display this information in light gray <e.g. Derived(Time)>.

Process type: You may select between discrete and continuous process type.
Signal type: Select the output signal type of your script (Float, Text, Logic, Integer, ..).
Signal descriptor: The signal descriptor describes the signal type in more details (e.g the bit width of a logic vector (default<bits=16>)). See below for more details. But in most case, you will use the standard settings (default<>) - Press CTRL-Space to view content proposals.
Domain Class/Base: The domain base is just required if your output signal has a different domain than the source signals. If not, just don't touch these settings.
Domain Range: Use this field to set the domain range, so the minimum and maximum value of the domain (e.g. 0 .. 1000 Hz)

Production Configuration

Member: Select the member name or id/index.

In case of Struct signals, enter the member name or id of the member. In case of Array signals, enter the member name or index of the member.

The id defines the position of the member definition, whereas the index means the position of the value. Only in case of arrays, id and index are equal.

Example with members (id/member name):

0: A
1: B
2: C

Struct

0: data; 1: data
1: data; 3: data (data index and member id not identical)
0: data;
0: data; 1: data; 2:data

Array

0: data; 1: data; 2:data (data index and member id identical)
0: data; 1: data; 2:data
0: data; 1: data; 2:data

Signal Handling

Keep tags: The output samples shall keep the tag information of each input sample.
Ignore 'None': Ignore 'None' samples of the input signals.
Hide identical: Check to hide sequence of identical samples (will only write to output signal in case of changed sample value/tag, may not have any effect in case of 'Continuous' process type).

The signal handling flags give the user more control over the output signal generation. If the "Keep tags" is checked, the output samples will get the tag information of each input samples. The "Ignore None" flag let the production ignore 'None' input samples. The "Hide identical" hides the production from generating sequences of identical samples.

Operation

Below you find the operation code for the production.

	
	 // iterate
	 while (iter.hasNext() && !isCanceled()) {
	
	     // value
	     Long current = iter.next();
	     CompoundValue cvalue = input.compound();
	     if (cvalue == null)
	         continue;
	
	     // none sample
	     boolean hasMember = cvalue.hasMember(member);
	     boolean isNone = cvalue.isNone() || !hasMember;
	     if (ignoreNone && isNone)
	         continue;
	
	     // member value
	     Object value = !isNone ? value(cvalue, member, targetWriter) : null;
	     if (!isNone && value == null) // could not convert
	         continue;
	
	     // tag
	     boolean tag = keepTags && cvalue != null && cvalue.isTagged();
	
	     // check identical
	     if (!hideIdentical || tag != previousTag || !Utils.equals(value, previousValue)) {
	
	         // write
	         if (isNone)
	             targetWriter.writeNone(current, tag);
	         else
	             targetWriter.writeSample(current, tag, value);
	
	         // remember
	         previousTag = tag;
	         previousValue = value;
	     }
	 }
	 break;

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