Examples of cascading.operation.expression.ExpressionFunction

cascading.operation.expression.ExpressionFunction
anino.net/">Janino compiler.
Specifically this function uses the {@link ExpressionEvaluator}, thus the syntax from that class is inherited here.
An expression may use field names directly as parameters in the expression, or field positions with the syntax "$n", where n is an integer.
Given an argument tuple with the fields "a" and "b", the following expression returns true:
a + b == $0 + $1

Further, the types of the tuple elements will be coerced into the given parameterTypes. Regardless of the actual tuple element values, they will be converted to the types expected by the expression.
Field names used in the expression should be valid Java variable names; for example, '+' or '-' are not allowed. Also the use of a field name that begins with an upper-case character is likely to fail and should be avoided.

      new Class[]{String.class, Integer.TYPE}, getOutputPath( "mergesum" ), SinkMode.REPLACE );


    Pipe lhsPipe = new Pipe( "sum-lhs" );
    Pipe rhsPipe = new Pipe( "sum-rhs" );


    rhsPipe = new Each( rhsPipe, new Fields( "char" ), new ExpressionFunction( Fields.ARGS, "$0.toLowerCase()", String.class ), Fields.REPLACE );


    Pipe sumPipe = new SumBy( Pipe.pipes( lhsPipe, rhsPipe ), new Fields( "char" ), new Fields( "num" ), new Fields( "sum" ), long.class, 2 );


    Map<String, Tap> tapMap = Cascades.tapsMap( Pipe.pipes( lhsPipe, rhsPipe ), Tap.taps( lhs, rhs ) );

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    Tap sink = getPlatform().getDelimitedFile( new Fields( "char", "average" ), "\t",
      new Class[]{String.class, Double.TYPE}, getOutputPath( "averagenull" ), SinkMode.REPLACE );


    Pipe pipe = new Pipe( "average" );


    ExpressionFunction function = new ExpressionFunction( Fields.ARGS, "3 == $0 ? null : $0", Integer.class );
    pipe = new Each( pipe, new Fields( "num" ), function, Fields.REPLACE );


    pipe = new AverageBy( pipe, new Fields( "char" ), new Fields( "num" ), new Fields( "average" ), AverageBy.Include.NO_NULLS, 2 );


    Flow flow = getPlatform().getFlowConnector().connect( source, sink, pipe );

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      new Class[]{String.class, Double.TYPE}, getOutputPath( "mergeaverage" ), SinkMode.REPLACE );


    Pipe lhsPipe = new Pipe( "average-lhs" );
    Pipe rhsPipe = new Pipe( "average-rhs" );


    rhsPipe = new Each( rhsPipe, new Fields( "char" ), new ExpressionFunction( Fields.ARGS, "$0.toLowerCase()", String.class ), Fields.REPLACE );


    Pipe sumPipe = new AverageBy( Pipe.pipes( lhsPipe, rhsPipe ), new Fields( "char" ), new Fields( "num" ), new Fields( "average" ), 2 );


    Map<String, Tap> tapMap = Cascades.tapsMap( Pipe.pipes( lhsPipe, rhsPipe ), Tap.taps( lhs, rhs ) );

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      getOutputPath( "multimerge+" + priorMerge ), SinkMode.REPLACE );


    Pipe lhsPipe = new Pipe( "multi-lhs" );
    Pipe rhsPipe = new Pipe( "multi-rhs" );


    rhsPipe = new Each( rhsPipe, new Fields( "char" ), new ExpressionFunction( Fields.ARGS, "$0.toLowerCase()", String.class ), Fields.REPLACE );


    class CustomHasher implements Hasher<Object>, Comparator<Comparable>, Serializable
      {
      @Override
      public int hashCode( Object value )

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    Pipe sourcePipe = new Pipe( "source" );
    Pipe lhsPipe = new Pipe( "count-lhs", sourcePipe );
    Pipe rhsPipe = new Pipe( "count-rhs", sourcePipe );


    // redundant, but illustrates case
    rhsPipe = new Each( rhsPipe, new Fields( "char" ), new ExpressionFunction( Fields.ARGS, "$0.toLowerCase()", String.class ), Fields.REPLACE );


    Pipe merge = new Merge( "first", lhsPipe, rhsPipe );
    Pipe countPipe = new CountBy( merge, new Fields( "char" ), new Fields( "count" ), 2 );


    lhsPipe = new Each( new Pipe( "lhs", countPipe ), new Identity() );

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    Tap source = getPlatform().getTextFile( new Fields( "line" ), inputFileApache200 );
    Tap sink = getPlatform().getTextFile( getOutputPath( "deeppipline" ), SinkMode.REPLACE );


    Pipe pipe = new Pipe( "pipeline" );


    Function function = new ExpressionFunction( new Fields( "count" ), "line.split( \"\\\\s\").length", String.class );
    pipe = new Each( pipe, new Fields( "line" ), function, Fields.ALL );


    int depth = 50;


    for( int i = 0; i < depth; i++ )
      {
      pipe = new Each( pipe, new Fields( "line" ), new Identity( new Fields( 0 ) ), Fields.ALL );
      pipe = new Each( pipe, new Fields( "count" ), new Identity( new Fields( 0 ) ), Fields.ALL );
      pipe = new Each( pipe, new Fields( "line" ), new Identity(), Fields.REPLACE );
      pipe = new Each( pipe, new Fields( "count" ), new Identity(), Fields.REPLACE );
      pipe = new Each( pipe, new Fields( "line", "count" ), new Identity() );
      pipe = new Each( pipe, new Fields( "line", "count" ), new Identity( new Fields( "line2", "count2" ) ), new Fields( "line", "count2" ) );
      pipe = new Each( pipe, new Fields( "count2" ), new Identity( new Fields( "count" ) ), new Fields( "line", "count" ) );
      }


    int modulo = 1000000;


    pipe = new Each( pipe, new Fields( "line" ), new ExpressionFunction( new Fields( "hash" ), "line.hashCode() % " + modulo, String.class ), Fields.ALL ); // want some collisions


    pipe = new GroupBy( pipe, new Fields( "hash" ) );


    for( int i = 0; i < depth; i++ )
      pipe = new Every( pipe, new Fields( "count" ), new Sum( new Fields( "sum" + ( i + 1 ) ) ) );

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