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Subject: Re: UIMA Ruta: assign distant annotations to features
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References: <561E1AAE.9090907@averbis.com>
From: =?UTF-8?Q?Peter_Kl=c3=bcgl?= <peter.kluegl@averbis.com>
Message-ID: <561E2874.1080903@averbis.com>
Date: Wed, 14 Oct 2015 12:03:32 +0200
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Sorry, there was a copy/paste mistake:

A # @B{-> GATHER(Projection, "a"=1)};

should read

A # @B{-> GATHER(Projection, "value"=1)};

Best,

Peter

Am 14.10.2015 um 11:04 schrieb Peter Klügl:
> Hi,
>
> there were some questions about assignments of annotations to features
> lately. This can by quite annoying right now. The problem is caused by
> two missing language elements: variables for storing annotations, which
> can be used to refer to annotation across rules. Explicit references to
> match contexts (rule elements), which facilitate the assignment within
> rules (local variables). I hope I will be able to add both language
> elements in UIMA Ruta 2.4.0.
>
> Here a short description how I solve these use cases in UIMA Ruta right now.
>
> Lets assume we some exemplary document:
>
> Some text
> A
> Some text
> More text
> B
> Some text
> B
>
> A and B shall be annotations of the type A and B. The goal is to create
> an annotation of type C for each annotation B with the same offsets as
> B, and to assign the annotation A to a feature "a" of the annotation C.
>
> In this simple case, this could be done with GATHER:
>
> A # @B{-> GATHER(C, "a"=1)};
>
> This rule starts to match on an annotation of type B (rule element 3).
> Then, it searches for the next annotation of the type A in front of it
> (rule element 1). If this is worked, then the GATHER action creates a
> new annotation of type C with the offsets of the current annotation B
> (rule element 3) and assigns the annotation matched by rule element 1 to
> the feature "a" of the annotation C. Then, the rule continues with the
> next annotations of type B. Thus, we get an annotation C for each
> annotation B if there is an annotation A somewhere before.
>
> Unfortunately, this is often not possible, e.g., because we need to
> assign additional values to other features of the annotation C, which is
> not supported by GATHER. Or we cannot directly use type A because the
> actual annotation we want to assign is stored in a feature of A.
>
> In order to overcome the missing languages elements that could be used
> to solve this problem, I normally introduce a projection type: an
> annotation that stores an annotation but is placed somewhere else in the
> document.
>
> DECLARE Projection (Annotation value);
> A # @B{-> GATHER(Projection, "a"=1)};
> B{-> CREATE(C, "x" = "String"), C.a=Projection.value};
>
> The first line declares a new type with a feature "value".
> The first rule (second line) connects the annotation A with each
> position of B. Then, the last rule creates the annotation C, stores
> "String" in the feature "x" and assigns the annotation stored in the
> feature "value" of an annotation Projection, which has the same offsets
> as B (the match context) in the feature "a" of the annotation C.
>
> This approach does not fit all use cases, but it can be modified to do
> so in most cases, e.g., the CREATE and feature assignment can be
> separated in order to use them in different BLOCKs, or a feature of A
> instead of A itself is stored in Projection.
>
> This problem can also be solved with other approaches in UIMA Ruta. Feel
> free to share your approaches with us. If anyone thinks that this mail
> was useful, then I would add it to the documentation.
>
> Best,
>
> Peter