@isna |

Test for missing value.

Syntax: @isna(arg)

arg: number or string

Return: number

Tests arg for a missing (NA) value or empty string.

Return value is an integer (0, 1). An argument which tests as missing returns a 1, and 0 otherwise.

When used with series objects, the test is performed for every observation in the workfile sample. Note that when used with matrix objects, the comparison is a missing value test of all of the elements of the matrix, and will return 0 if any element is not missing. Element tests are available in
@eisna

Examples

The test

scalar f = @isna(NA)

returns the value 1, not an NA.

If SER1 is a numeric series,

series s2 = @isna(ser1)

tests SER1 for an empty string for each observation in the workfile sample.

Consider the comparison

vector v1 = @fill(1, 2, NA)

scalar f2 = @isna(v1)

evaluates the entire vector V1, and returns 0 since some of the elements of V1 are not missing. Define the string objects

string s1 = "abc"

string s2 = ""

Then

scalar b1 = @isna("abc")

scalar b2 = @isna(s1)

sets the scalar objects B1 and B2 to 0, while

scalar c1 = @isna("")

sets C1 to 1.

If ALPHA1 is an alpha series,

series d1 = @isna(alpha1)

tests ALPHA1 for an empty string for each observation in the workfile sample.

svector svec1 = @fill("abc", "abc", "")

scalar sc1 = @isna(svec1)

returns 0, since the command is a full test of SC1 for missing values and returns a 0 if any element is not equal.

Cross-references