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ismissing()

Usage:
ismissing(x) where x is REAL, LOGICAL or CHARACTER or a structure all of
  whose components are REAL, LOGICAL, or CHARACTER



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