JSL Summarize Command Creates 2 lists, one that behaves "normally", the other not.

[#1]

Hi Folks,

The code below creates a data table and then creates two lists in the Summarize command, one for the By variable (date_list) and one for the Max variable (data_list).  The date_list is fully accessible using standard List commands (see code at bottom), but the data_list isn't a list as far as Is List (data_list) is concerned.  In addition, I can't count the number of items in the list, nor Show the location of a specific value in the data_list.  Is this normal behavior for a list or am I missing something subtle here about lists?  Any help would be appreciated.  Thanks

Clear Log();

Names Default To Here(1);

dt1 = New Table( "Test",

  Add Rows( 20 ),

  New Column( "Date",

  Numeric,

  Continuous,

  Format( "m/d/y h:m", 10 ),

  Input Format( "m/d/y h:m" ),

  Set Values(

  [1767245800, 1771173900, 1805155800, 1809197400, 1843086800, 1838161000, 1889049900, 1893293200,

  1896320800, 1900281600, 1950766400, 1955499200, 1957751200, 1964247600, 1990396800, 1995976400,

  2023788000, 2029549600, 2051488600, 2056959000]

  )

  ),

  New Column( "Data",

  Numeric,

  Continuous,

  Format( "Best", 12 ),

  Set Values( [34, 45, ., 56, 99, 67, 12, 78, 53, 89, 77, 90, ., 12, 73, 23, 12, 34, 6, 45] )

  ),

  New Column( "Year", Numeric, Continuous, Format( "Best", 12 ), Formula( Year( :Date ) ), Lock( 1 ) ),

  New Column( "Hour", Numeric, Continuous, Format( "Best", 12 ), Formula( Hour( :Date ) ), Lock( 1 ) )

);

Wait( 2 );

// Get the highest growth for each day

Summarize( date_list = by( :Date ), data_list = Max( :Data ) );

Is List( date_list );

N Items ( date_list );

Show( Loc( date_list, "03/15/1961 12:10 AM" ));

Is List( data_list );

N Items ( data_list );

Show( Loc( data_list, 45 ));

[#2 · Accepted solution]

It's only the by() result of summarize that is a list. The numerical output is typically a matrix (i.e. a vector). Use matrix commands or convert the matrix to a list.

Compare these alternatives:

Is Matrix( data_list );

N Row( data_list );

Show( Loc( data_list == 45 ));

Is List( data_list = As List( data_list ) );

N Items( data_list );

Show( Loc( data_list, 45 ) );

[#3]

Ah, as usual, the devil is in the details.  Thanks for the description and alternatives.  That helped me understand the difference between a list and matrix a lot better.