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JSL Set Operations

A question about using sets of column names. You can use JSL's associative arrays to perform set operations. The methods <

// make three sets
rgb = associativearray({"red","green","blue"});
cmy = associativearray({"cyan","magenta","yellow"});
bw = associativearray({"black","white"});
// join them together
all = rgb;
all<<INSERT></INSERT>

The question was posed in terms of sets of column names, and this example uses the associative array set operation < to get the difference between the set of all columns and the set of columns containing the letter "i".

 

// keep only the columns with an "i" in the name

dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
allnames = dt << getcolumnnames( "string" );

inames = {};
For( i = 1, i <= N Items( allnames ), i++,
 If( Contains( allnames[i], "i" ),
  Insert Into( inames, allnames[i] )
 )
);

allset = Associative Array( allnames ); // {"name", "age", "sex", "height", "weight"}
iset = Associative Array( inames ); // {"height", "weight"}

allset << Remove( iset ); // the "not i" set...
notinames = allset<<GETKEYS></GETKEYS>

 

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Using Associative Arrays as sets. Intersect, Union, Difference.

Re: JSL Set Operations

This is very nice.  I hadn't thought to use associative arrays like this.  I've had situations in the past where I've used a list of object references, and I wanted search through the list to eliminate objects that met certain conditions.  Using list operations was pretty slow and the control logic was complicated.  I can see how this would make it much easier.  I'm copying and pasting your example code to add to my "JSL collection" for future reference!