user manual

103

Handling Missing Values

The @ functions can be used in conjunction with the @FIELD function to identify th e presen ce

of blank or nul

l values in one or more ﬁelds. The ﬁelds can simply be ﬂagged when blank

or null values are present, or they can be ﬁlled with replacement values or used in a va r iety

of other operatio ns.

You can count nulls across a list of ﬁelds, as follows:

count_nulls(['cardtenure' 'card2tenure' 'card3tenure'])

When usin g any of the functions that accept a list of ﬁelds as input , the special functions

@FIELDS_BETWEEN and @FIELDS_MATCHING can be use d, as shown in the following ex ample:

count_nulls(@FIELDS_MAT

CHING('card*'))

Figure 6-2

Using a Filler node to replace blank values with 0 in the selected field

You can use the undef functi

on t o ﬁll ﬁelds with the system-missing value, displayed as $null$.

For example, to replace any numeric value, you could use a conditional statem ent, such as:

if not(Age > 17) or not(Age < 66) then undef else Age endif

This replaces anything that is not in the range with a system-mis sing value, displayed as $null$. By

using the not() function, you can c atch all other n um eric values, including any negatives. For more

informa tion, see the topic Fun

ctions Handling Blanks and Null Values in Chapter 8 on p. 156.