<html lang="en"> <head> <title>Missing Data - GNU Octave</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="GNU Octave"> <meta name="generator" content="makeinfo 4.13"> <link title="Top" rel="start" href="index.html#Top"> <link rel="up" href="Built_002din-Data-Types.html#Built_002din-Data-Types" title="Built-in Data Types"> <link rel="prev" href="Numeric-Objects.html#Numeric-Objects" title="Numeric Objects"> <link rel="next" href="String-Objects.html#String-Objects" title="String Objects"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family:serif; font-weight:normal; } span.sansserif { font-family:sans-serif; font-weight:normal; } --></style> </head> <body> <div class="node"> <a name="Missing-Data"></a> <p> Next: <a rel="next" accesskey="n" href="String-Objects.html#String-Objects">String Objects</a>, Previous: <a rel="previous" accesskey="p" href="Numeric-Objects.html#Numeric-Objects">Numeric Objects</a>, Up: <a rel="up" accesskey="u" href="Built_002din-Data-Types.html#Built_002din-Data-Types">Built-in Data Types</a> <hr> </div> <h4 class="subsection">3.1.2 Missing Data</h4> <p><a name="index-missing-data-212"></a> It is possible to represent missing data explicitly in Octave using <code>NA</code> (short for “Not Available”). Missing data can only be represented when data is represented as floating point numbers. In this case missing data is represented as a special case of the representation of <code>NaN</code>. <!-- NA src/data.cc --> <p><a name="doc_002dNA"></a> <div class="defun"> — Built-in Function: <b>NA</b><var><a name="index-NA-213"></a></var><br> — Built-in Function: <b>NA</b> (<var>n</var>)<var><a name="index-NA-214"></a></var><br> — Built-in Function: <b>NA</b> (<var>n, m</var>)<var><a name="index-NA-215"></a></var><br> — Built-in Function: <b>NA</b> (<var>n, m, k, <small class="dots">...</small></var>)<var><a name="index-NA-216"></a></var><br> — Built-in Function: <b>NA</b> (<var><small class="dots">...</small>, class</var>)<var><a name="index-NA-217"></a></var><br> <blockquote><p>Return a scalar, matrix, or N-dimensional array whose elements are all equal to the special constant used to designate missing values. <p>Note that NA always compares not equal to NA (NA != NA). To find NA values, use the <code>isna</code> function. <p>When called with no arguments, return a scalar with the value ‘<samp><span class="samp">NA</span></samp>’. When called with a single argument, return a square matrix with the dimension specified. When called with more than one scalar argument the first two arguments are taken as the number of rows and columns and any further arguments specify additional matrix dimensions. The optional argument <var>class</var> specifies the return type and may be either "double" or "single". <!-- Texinfo @sp should work but in practice produces ugly results for HTML. --> <!-- A simple blank line produces the correct behavior. --> <!-- @sp 1 --> <p class="noindent"><strong>See also:</strong> <a href="doc_002disna.html#doc_002disna">isna</a>. </p></blockquote></div> <!-- isna src/mappers.cc --> <p><a name="doc_002disna"></a> <div class="defun"> — Mapping Function: <b>isna</b> (<var>x</var>)<var><a name="index-isna-218"></a></var><br> <blockquote><p>Return a logical array which is true where the elements of <var>x</var> are NA (missing) values and false where they are not. For example: <pre class="example"> isna ([13, Inf, NA, NaN]) ⇒ [ 0, 0, 1, 0 ] </pre> <!-- Texinfo @sp should work but in practice produces ugly results for HTML. --> <!-- A simple blank line produces the correct behavior. --> <!-- @sp 1 --> <p class="noindent"><strong>See also:</strong> <a href="doc_002disnan.html#doc_002disnan">isnan</a>, <a href="doc_002disinf.html#doc_002disinf">isinf</a>, <a href="doc_002disfinite.html#doc_002disfinite">isfinite</a>. </p></blockquote></div> </body></html>