<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ --> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Missing Data (GNU Octave (version 5.1.0))</title> <meta name="description" content="Missing Data (GNU Octave (version 5.1.0))"> <meta name="keywords" content="Missing Data (GNU Octave (version 5.1.0))"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="makeinfo"> <link href="index.html#Top" rel="start" title="Top"> <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> <link href="Built_002din-Data-Types.html#Built_002din-Data-Types" rel="up" title="Built-in Data Types"> <link href="String-Objects.html#String-Objects" rel="next" title="String Objects"> <link href="Numeric-Objects.html#Numeric-Objects" rel="prev" title="Numeric Objects"> <style type="text/css"> <!-- a.summary-letter {text-decoration: none} blockquote.indentedblock {margin-right: 0em} blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} blockquote.smallquotation {font-size: smaller} div.display {margin-left: 3.2em} div.example {margin-left: 3.2em} div.lisp {margin-left: 3.2em} div.smalldisplay {margin-left: 3.2em} div.smallexample {margin-left: 3.2em} div.smalllisp {margin-left: 3.2em} kbd {font-style: oblique} pre.display {font-family: inherit} pre.format {font-family: inherit} pre.menu-comment {font-family: serif} pre.menu-preformatted {font-family: serif} pre.smalldisplay {font-family: inherit; font-size: smaller} pre.smallexample {font-size: smaller} pre.smallformat {font-family: inherit; font-size: smaller} pre.smalllisp {font-size: smaller} span.nolinebreak {white-space: nowrap} span.roman {font-family: initial; font-weight: normal} span.sansserif {font-family: sans-serif; font-weight: normal} ul.no-bullet {list-style: none} --> </style> <link rel="stylesheet" type="text/css" href="octave.css"> </head> <body lang="en"> <a name="Missing-Data"></a> <div class="header"> <p> Next: <a href="String-Objects.html#String-Objects" accesskey="n" rel="next">String Objects</a>, Previous: <a href="Numeric-Objects.html#Numeric-Objects" accesskey="p" rel="prev">Numeric Objects</a>, Up: <a href="Built_002din-Data-Types.html#Built_002din-Data-Types" accesskey="u" rel="up">Built-in Data Types</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> </div> <hr> <a name="Missing-Data-1"></a> <h4 class="subsection">3.1.2 Missing Data</h4> <a name="index-missing-data"></a> <p>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>. </p> <a name="XREFNA"></a><dl> <dt><a name="index-NA"></a><em></em> <strong>NA</strong></dt> <dt><a name="index-NA-1"></a><em></em> <strong>NA</strong> <em>(<var>n</var>)</em></dt> <dt><a name="index-NA-2"></a><em></em> <strong>NA</strong> <em>(<var>n</var>, <var>m</var>)</em></dt> <dt><a name="index-NA-3"></a><em></em> <strong>NA</strong> <em>(<var>n</var>, <var>m</var>, <var>k</var>, …)</em></dt> <dt><a name="index-NA-4"></a><em></em> <strong>NA</strong> <em>(…, <var>class</var>)</em></dt> <dd><p>Return a scalar, matrix, or N-dimensional array whose elements are all equal to the special constant used to designate missing values. </p> <p>Note that NA always compares not equal to NA (NA != NA). To find NA values, use the <code>isna</code> function. </p> <p>When called with no arguments, return a scalar with the value ‘<samp>NA</samp>’. </p> <p>When called with a single argument, return a square matrix with the dimension specified. </p> <p>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. </p> <p>The optional argument <var>class</var> specifies the return type and may be either <code>"double"</code> or <code>"single"</code>. </p> <p><strong>See also:</strong> <a href="#XREFisna">isna</a>. </p></dd></dl> <a name="XREFisna"></a><dl> <dt><a name="index-isna"></a><em></em> <strong>isna</strong> <em>(<var>x</var>)</em></dt> <dd><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. </p> <p>For example: </p> <div class="example"> <pre class="example">isna ([13, Inf, NA, NaN]) ⇒ [ 0, 0, 1, 0 ] </pre></div> <p><strong>See also:</strong> <a href="Finding-Elements-and-Checking-Conditions.html#XREFisnan">isnan</a>, <a href="Finding-Elements-and-Checking-Conditions.html#XREFisinf">isinf</a>, <a href="Finding-Elements-and-Checking-Conditions.html#XREFisfinite">isfinite</a>. </p></dd></dl> </body> </html>