union - Pacific Knowledge Systems

union combines two sets a single set. The simplest syntax is

X union Y

where X and Y are sub-expressions giving sets. For example, in a lab where the tests requested for a patient are put as comma-separated values in the two distinct attributes TestsRequested and TestsOrdered, we could get the complete set of tests ordered for a patient using this expression:

TestsRequested as set union TestsOrdered as set

union also combines two sets of attributes into a single set. The syntax is

{ names } in range [lower, upper] union { names } in range [lower, upper]

where:

names are comma separated lists of attribute names or group attribute names

lower and upper are constants or numbers defining the ranges.

For example, suppose you want a comment to contain the names from two sets of allergens

{milk, cod, peanut} in range [15.0,50)

and

{wheat, soya} in range [50,1000]

You can define a calculated value attribute HighAllergens as

{milk, cod, peanut} in range [15.0,50) union {wheat, soya} in range [50,1000]

and the case would then appear as:

age            6
sex            F
milk           0.0
peanut         43.5
cod            12.1
soya           64.6
wheat          25.3
HighAllergens	soya (64.6) and peanut (43.5)

A comment could now be created that used the expression HighAllergens to list those allergens.

Note the following:

As with all lists of attributes, the attribute names whose values are highest are listed first,
If more than one attribute value is within the range, the attribute names and values are separated by commas, with the word “and” separating the last two.