Named Entity Recognition 25.3
Named Entity Recognition User and Programming Guide

# Find Repeated Matches

A repeated match occurs when Named Entity Recognition finds another match (exactly the same text), at a different location in the input (a different offset). For example, if you are searching some input text for telephone numbers, Named Entity Recognition could find a match "564123". The same text could occur later in the document and would result in a repeated match. Repeated matches might belong to the same entity, but this is not always the case because multiple entities can match the same text.

TIP: Named Entity Recognition does not return repeated matches if you configure the engine with EnableUniqueMatches set to `TRUE`.

Named Entity Recognition normally returns matches in the order that they appear in the input, but you might prefer to process a match, followed by all of its repeated matches, and then return to the next unique match. In extreme cases, where the matched text is repeated many times, this provides a convenient way to stop processing and move on to the next unique match or maybe even the next document.

Each Named Entity Recognition API provides a way to find the next repeated match. The SDK includes sample programs, in each language, that demonstrate this functionality.

NOTE: This feature is not supported for streaming input or in table mode.

## C API

In the C API, instead of calling `EdkGetNextMatch` you can call `EdkGetNextRepeatedMatch`.

If the input contains another match with the same text as the current match, you can then call `EdkGetRepeatedMatchByteOffset` and `EdkGetRepeatedMatchCodepointOffset` to establish the location of the repeated match.

You can call `EdkGetNextRepeatedMatch` repeatedly. If the matched text does not occur again, Named Entity Recognition returns `EdkNoMatch` and you can proceed to the next unique match by calling `EdkGetNextMatch`.

Any repeated matches that you access using `EdkGetNextRepeatedMatch` are not returned by subsequent calls to `EdkGetNextMatch`. By using `EdkGetNextRepeatedMatch` you are changing the order in which the matches are returned.

The following code sample demonstrates how you might use these functions. For more information about these functions, refer to the API reference documentation.

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    while (EdkGetNextMatch(session) == EdkSuccess)
    {
        // call match accessors and do something with the information

        while (EdkGetNextRepeatedMatch(session) == EdkSuccess)
        {
            size_t nRepCodepointOffset = 0;
            size_t nRepByteOffset = 0;
            EdkGetRepeatedMatchCodepointOffset(session, &nRepCodepointOffset);
            EdkGetRepeatedMatchByteOffset(session, &nRepByteOffset);

            // do something with the offsets...
        }
    }

## Java API

The repeated matches functionality in the Java API is similar to the C API. You can iterate over repeated matches as shown in the following code sample. You can call the `getByteOffset()` and `getCodepointOffset()` methods to establish the position of a repeated match.

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    for (EDKMatch match : session)
    {
        // call match accessors and do something with the information

        for (EDKRepeatedMatchOffset repeat : match)
        {
            long byteOffset = repeat.getByteOffset();
            long codepointOffset = repeat.getCodepointOffset();

            // do something with the offsets
        }
    }

## .NET API

The repeated matches functionality in the .NET API is similar to the C API. You can iterate over repeated matches as shown in the following code sample. The properties `ByteOffset` and `CodepointOffset` provide the position of a repeated match.

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    foreach (IExtractionMatch match in session)
    {
        // call match accessors and do something with the information

        foreach (IExtractionRepeatedMatch repeat in match.RepeatedMatches)
        {
            long byteOffset = repeat.ByteOffset;
            long codepointOffset = repeat.CodepointOffset;

            // do something with the offsets
        }
    }

## Python API

In the Python API, repeated matches is a built-in option in `edk.sdk`. After you create a session, set its `.repeated_matches` property to True. Iterating over matches then automatically calls `GetNextRepeatedMatch` internally, where applicable, to yield all occurrences of the current match text, and then move on to the next unique match. For example:

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    with engine.session() as session:
        session.repeated_matches =True
        for match in session:
        # This gets the first match, then repeats, then the next unique match, and so on.
        ... do something with match ...

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Version 25.3 | Last updated July 2025

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Product: Knowledge Discovery Named Entity Recognition 25.3

Topic Title: Find Repeated Matches