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Usage:
ismissing(x) where x is REAL, LOGICAL or CHARACTER or a structure all of
whose components are REAL, LOGICAL, or CHARACTER
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Keywords:
macros, general, missing values, variables, null variables
ismissing(x) returns a LOGICAL variable (with the same shape as x) which
is True where x is MISSING and False where x is not MISSING. x must be
a vector, matrix, or array. If x is a CHARACTER variable, an empty
string ("") is considered to be a missing value.
If x is a NULL variable, ismissing(x) is NULL. See topic 'NULL'.
It is also acceptable for x to be a structure, whose non-structure
components are vectors, matrices or arrays. In that case, ismissing()
returns a structure of the same form, each of whose non-structure
components is the result of applying ismissing() to the corresponding
component of x.
ismissing(x) has the same labels as x, if any.
Examples:
ismissing(vector(1, 3, ?, 7)) and ismissing(vector("A","B","","Z"))
both return vector(F, F, T, F)
x[vector(ismissing(x))] <- -1 replaces all MISSING values in x by -1.
sum(vector(ismissing(x))) returns the number of MISSING values in x,
whether x is a vector, matrix, array, or structure.
See also anymissing(), sum().
Gary Oehlert
2003-01-15