Big-Data-HPC-Platform/docs/ECLLanguageReference/ECLR_mods/Expr-InOps.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<sect1 id="IN_Operator">
  <title>IN Operator<indexterm>
      <primary>IN</primary>
    </indexterm><indexterm>
      <primary>IN Operator</primary>
    </indexterm></title>

  <para><emphasis>value </emphasis><emphasis role="bold">IN
  </emphasis><emphasis>value_set</emphasis></para>

  <informaltable colsep="1" frame="all" rowsep="1">
    <tgroup cols="2">
      <colspec align="left" colwidth="122.40pt" />

      <colspec />

      <tbody>
        <row>
          <entry><emphasis>value</emphasis></entry>

          <entry>The value to find in the <emphasis>value_set</emphasis>. This
          is usually a single value, but if the <emphasis>value_set</emphasis>
          is a DICTIONARY with a multiple-component key, this may also be a
          ROW.</entry>
        </row>

        <row>
          <entry><emphasis>value_set</emphasis></entry>

          <entry>A set of values. This may be a set expression, the SET
          function, or a DICTIONARY.</entry>
        </row>
      </tbody>
    </tgroup>
  </informaltable>

  <para>The <emphasis role="bold">IN</emphasis> operator is shorthand for a
  collection of OR conditions. It is an operator that will search a set to
  find an inclusion, resulting in a Boolean return. Using IN is much more
  efficient than the equivalent OR expression.</para>

  <para>Example:</para>

  <programlisting>ABCset := ['A', 'B', 'C'];
IsABCStatus := Person.Status IN ABCset;
    //This code is directly equivalent to:
    // IsABCStatus := Person.Status = 'A' OR
    //                Person.Status = 'B' OR
    //                Person.Status = 'C';
       
IsABC(STRING1 char) := char IN ABCset;
Trades_ABCstat := Trades(IsABC(rate));
    // Trades_ABCstat is a record set definition of all those
    // trades with a trade status of A, B, or C

//SET function examples
r := {STRING1 Letter};
SomeFile := DATASET([{'A'},{'B'},{'C'},{'D'},{'E'},
                     {'F'},{'G'},{'H'},{'I'},{'J'}],r);
x := SET(SomeFile(Letter &gt; 'C'),Letter);
y := 'A' IN x;  //results in FALSE
z := 'D' IN x;  //results in TRUE

//DICTIONARY examples:
rec := {STRING color,UNSIGNED1 code};
ColorCodes := DATASET([{'Black' ,0 },
                       {'Brown' ,1 },
                       {'Red'   ,2 },
                       {'White' ,3 }], rec);

CodeColorDCT  := DICTIONARY(ColorCodes,{Code =&gt; Color});
OUTPUT(6 IN CodeColorDCT);     //true

ColorCodesDCT := DICTIONARY(ColorCodes,{Color,Code});
OUTPUT(ROW({'Red',2},rec) IN ColorCodesDCT);
</programlisting>

  <para>See Also: <link linkend="Basic_Attribute_Types">Basic Definition
  Types</link>, <link linkend="Basic_Attribute_Types">Definition Types</link>
  (<link linkend="Set_Attributes">Set Definitions</link>), <link
  linkend="Logical_Operators">Logical Operators</link>, <link
  linkend="PARSE_Pattern_Value_Types">PATTERN</link>, <link
  linkend="DICTIONARY">DICTIONARY</link>, <link linkend="ROW">ROW</link>,
  <link linkend="SET">SET</link>, <link linkend="Recordset_Filtering">Sets and
  Filters</link>, <link linkend="SET_OF">SET OF</link>, <link
  linkend="Set_Operators">Set Operators</link></para>
</sect1>