frequency_table_with_null - ObjectVision/GeoDMS GitHub Wiki

Aggregation functions frequency_table_with_null

• frequency_table_with_null(a)
• frequency_table_with_null(a, relation)

• frequency_table_with_null(a) results in a parameter with a string listing all values of attribute a — including null values — together with how often each value occurs, separated by "; ".
• frequency_table_with_null(a, relation) results in an attribute with such strings, one per partition defined by relation. The domain unit of the resulting attribute is the values unit of the relation. Each partition string contains the value-count pairs for all values of a (including null) belonging to that partition.

The result per partition is a string of the form value1: count1; value2: count2; ..., where:

• values are listed in ascending order (the order defined by the values unit of attribute a),
• only values with a non-zero count are included,
• null values in a are included in the frequency table and are shown as <null>: count.

This function is identical to frequency_table except that null values in a are counted and included in the result string. Elements mapped to a null partition (null relation value) are still excluded from all groups.

• attribute a with any scalar value type
• relation with value type of the group CanBeDomainUnit

1. The domain of argument a and relation must match.

14.4.0

parameter<string> freqLifeStyleCodeWithNull := frequency_table_with_null(City/LifeStyleCode);
// result = "0: 2; 1: 3; 2: 1; <null>: 1"

attribute<string> freqLifeStyleCodeWithNullPerRegion (Region) := frequency_table_with_null(City/LifeStyleCode, City/Region_rel);

domain City, nr of rows = 7

domain Region, nr of rows = 5

City 6 (LifeStyleCode = null, Region_rel = 3) is included in Region 3's count as <null>: 1. City 5 (Region_rel = null) is excluded from all groups.

• frequency_table - variant that excludes null values of a from the frequency table
• as_unique_list - like frequency_table but only lists the distinct values, without the counts
• modus - returns only the most frequently occurring value
• unique_count - returns the number of distinct non-null values