usr
/
share
/
doc
/
python-docs-2.7.5
/
html
/
library
➕ New
📤 Upload
✎ Editing:
timeit.html
← Back
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>26.6. timeit — Measure execution time of small code snippets — Python 2.7.5 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '2.7.5', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 2.7.5 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="top" title="Python 2.7.5 documentation" href="../index.html" /> <link rel="up" title="26. Debugging and Profiling" href="debug.html" /> <link rel="next" title="26.7. trace — Trace or track Python statement execution" href="trace.html" /> <link rel="prev" title="26.5. hotshot — High performance logging profiler" href="hotshot.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <script type="text/javascript" src="../_static/copybutton.js"></script> </head> <body> <div class="related"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="trace.html" title="26.7. trace — Trace or track Python statement execution" accesskey="N">next</a> |</li> <li class="right" > <a href="hotshot.html" title="26.5. hotshot — High performance logging profiler" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="http://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.5 documentation</a> » </li> <li><a href="index.html" >The Python Standard Library</a> »</li> <li><a href="debug.html" accesskey="U">26. Debugging and Profiling</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="module-timeit"> <span id="timeit-measure-execution-time-of-small-code-snippets"></span><h1>26.6. <a class="reference internal" href="#module-timeit" title="timeit: Measure the execution time of small code snippets."><tt class="xref py py-mod docutils literal"><span class="pre">timeit</span></tt></a> — Measure execution time of small code snippets<a class="headerlink" href="#module-timeit" title="Permalink to this headline">¶</a></h1> <p class="versionadded"> <span class="versionmodified">New in version 2.3.</span></p> <p id="index-0"><strong>Source code:</strong> <a class="reference external" href="http://hg.python.org/cpython/file/2.7/Lib/timeit.py">Lib/timeit.py</a></p> <hr class="docutils" /> <p>This module provides a simple way to time small bits of Python code. It has both a <a class="reference internal" href="#command-line-interface"><em>Command-Line Interface</em></a> as well as a <a class="reference internal" href="#python-interface"><em>callable</em></a> one. It avoids a number of common traps for measuring execution times. See also Tim Peters’ introduction to the “Algorithms” chapter in the <em>Python Cookbook</em>, published by O’Reilly.</p> <div class="section" id="basic-examples"> <h2>26.6.1. Basic Examples<a class="headerlink" href="#basic-examples" title="Permalink to this headline">¶</a></h2> <p>The following example shows how the <a class="reference internal" href="#command-line-interface"><em>Command-Line Interface</em></a> can be used to compare three different expressions:</p> <div class="highlight-sh"><div class="highlight"><pre><span class="nv">$ </span>python -m timeit <span class="s1">'"-".join(str(n) for n in range(100))'</span> 10000 loops, best of 3: 40.3 usec per loop <span class="nv">$ </span>python -m timeit <span class="s1">'"-".join([str(n) for n in range(100)])'</span> 10000 loops, best of 3: 33.4 usec per loop <span class="nv">$ </span>python -m timeit <span class="s1">'"-".join(map(str, range(100)))'</span> 10000 loops, best of 3: 25.2 usec per loop </pre></div> </div> <p>This can be achieved from the <a class="reference internal" href="#python-interface"><em>Python Interface</em></a> with:</p> <div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">timeit</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="s">'"-".join(str(n) for n in range(100))'</span><span class="p">,</span> <span class="n">number</span><span class="o">=</span><span class="mi">10000</span><span class="p">)</span> <span class="go">0.8187260627746582</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="s">'"-".join([str(n) for n in range(100)])'</span><span class="p">,</span> <span class="n">number</span><span class="o">=</span><span class="mi">10000</span><span class="p">)</span> <span class="go">0.7288308143615723</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="s">'"-".join(map(str, range(100)))'</span><span class="p">,</span> <span class="n">number</span><span class="o">=</span><span class="mi">10000</span><span class="p">)</span> <span class="go">0.5858950614929199</span> </pre></div> </div> <p>Note however that <a class="reference internal" href="#module-timeit" title="timeit: Measure the execution time of small code snippets."><tt class="xref py py-mod docutils literal"><span class="pre">timeit</span></tt></a> will automatically determine the number of repetitions only when the command-line interface is used. In the <a class="reference internal" href="#timeit-examples"><em>Examples</em></a> section you can find more advanced examples.</p> </div> <div class="section" id="python-interface"> <span id="id1"></span><h2>26.6.2. Python Interface<a class="headerlink" href="#python-interface" title="Permalink to this headline">¶</a></h2> <p>The module defines three convenience functions and a public class:</p> <dl class="function"> <dt id="timeit.timeit"> <tt class="descclassname">timeit.</tt><tt class="descname">timeit</tt><big>(</big><em>stmt='pass'</em>, <em>setup='pass'</em>, <em>timer=<default timer></em>, <em>number=1000000</em><big>)</big><a class="headerlink" href="#timeit.timeit" title="Permalink to this definition">¶</a></dt> <dd><p>Create a <a class="reference internal" href="#timeit.Timer" title="timeit.Timer"><tt class="xref py py-class docutils literal"><span class="pre">Timer</span></tt></a> instance with the given statement, <em>setup</em> code and <em>timer</em> function and run its <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a> method with <em>number</em> executions.</p> <p class="versionadded"> <span class="versionmodified">New in version 2.6.</span></p> </dd></dl> <dl class="function"> <dt id="timeit.repeat"> <tt class="descclassname">timeit.</tt><tt class="descname">repeat</tt><big>(</big><em>stmt='pass'</em>, <em>setup='pass'</em>, <em>timer=<default timer></em>, <em>repeat=3</em>, <em>number=1000000</em><big>)</big><a class="headerlink" href="#timeit.repeat" title="Permalink to this definition">¶</a></dt> <dd><p>Create a <a class="reference internal" href="#timeit.Timer" title="timeit.Timer"><tt class="xref py py-class docutils literal"><span class="pre">Timer</span></tt></a> instance with the given statement, <em>setup</em> code and <em>timer</em> function and run its <a class="reference internal" href="#timeit.Timer.repeat" title="timeit.Timer.repeat"><tt class="xref py py-meth docutils literal"><span class="pre">repeat()</span></tt></a> method with the given <em>repeat</em> count and <em>number</em> executions.</p> <p class="versionadded"> <span class="versionmodified">New in version 2.6.</span></p> </dd></dl> <dl class="function"> <dt id="timeit.default_timer"> <tt class="descclassname">timeit.</tt><tt class="descname">default_timer</tt><big>(</big><big>)</big><a class="headerlink" href="#timeit.default_timer" title="Permalink to this definition">¶</a></dt> <dd><p>Define a default timer, in a platform-specific manner. On Windows, <a class="reference internal" href="time.html#time.clock" title="time.clock"><tt class="xref py py-func docutils literal"><span class="pre">time.clock()</span></tt></a> has microsecond granularity, but <a class="reference internal" href="time.html#time.time" title="time.time"><tt class="xref py py-func docutils literal"><span class="pre">time.time()</span></tt></a>‘s granularity is 1/60th of a second. On Unix, <a class="reference internal" href="time.html#time.clock" title="time.clock"><tt class="xref py py-func docutils literal"><span class="pre">time.clock()</span></tt></a> has 1/100th of a second granularity, and <a class="reference internal" href="time.html#time.time" title="time.time"><tt class="xref py py-func docutils literal"><span class="pre">time.time()</span></tt></a> is much more precise. On either platform, <a class="reference internal" href="#timeit.default_timer" title="timeit.default_timer"><tt class="xref py py-func docutils literal"><span class="pre">default_timer()</span></tt></a> measures wall clock time, not the CPU time. This means that other processes running on the same computer may interfere with the timing.</p> </dd></dl> <dl class="class"> <dt id="timeit.Timer"> <em class="property">class </em><tt class="descclassname">timeit.</tt><tt class="descname">Timer</tt><big>(</big><em>stmt='pass'</em>, <em>setup='pass'</em>, <em>timer=<timer function></em><big>)</big><a class="headerlink" href="#timeit.Timer" title="Permalink to this definition">¶</a></dt> <dd><p>Class for timing execution speed of small code snippets.</p> <p>The constructor takes a statement to be timed, an additional statement used for setup, and a timer function. Both statements default to <tt class="docutils literal"><span class="pre">'pass'</span></tt>; the timer function is platform-dependent (see the module doc string). <em>stmt</em> and <em>setup</em> may also contain multiple statements separated by <tt class="docutils literal"><span class="pre">;</span></tt> or newlines, as long as they don’t contain multi-line string literals.</p> <p>To measure the execution time of the first statement, use the <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a> method. The <a class="reference internal" href="#timeit.Timer.repeat" title="timeit.Timer.repeat"><tt class="xref py py-meth docutils literal"><span class="pre">repeat()</span></tt></a> method is a convenience to call <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a> multiple times and return a list of results.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 2.6: </span>The <em>stmt</em> and <em>setup</em> parameters can now also take objects that are callable without arguments. This will embed calls to them in a timer function that will then be executed by <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a>. Note that the timing overhead is a little larger in this case because of the extra function calls.</p> <dl class="method"> <dt id="timeit.Timer.timeit"> <tt class="descname">timeit</tt><big>(</big><em>number=1000000</em><big>)</big><a class="headerlink" href="#timeit.Timer.timeit" title="Permalink to this definition">¶</a></dt> <dd><p>Time <em>number</em> executions of the main statement. This executes the setup statement once, and then returns the time it takes to execute the main statement a number of times, measured in seconds as a float. The argument is the number of times through the loop, defaulting to one million. The main statement, the setup statement and the timer function to be used are passed to the constructor.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p>By default, <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a> temporarily turns off <a class="reference internal" href="../glossary.html#term-garbage-collection"><em class="xref std std-term">garbage collection</em></a> during the timing. The advantage of this approach is that it makes independent timings more comparable. This disadvantage is that GC may be an important component of the performance of the function being measured. If so, GC can be re-enabled as the first statement in the <em>setup</em> string. For example:</p> <div class="last highlight-python"><div class="highlight"><pre><span class="n">timeit</span><span class="o">.</span><span class="n">Timer</span><span class="p">(</span><span class="s">'for i in xrange(10): oct(i)'</span><span class="p">,</span> <span class="s">'gc.enable()'</span><span class="p">)</span><span class="o">.</span><span class="n">timeit</span><span class="p">()</span> </pre></div> </div> </div> </dd></dl> <dl class="method"> <dt id="timeit.Timer.repeat"> <tt class="descname">repeat</tt><big>(</big><em>repeat=3</em>, <em>number=1000000</em><big>)</big><a class="headerlink" href="#timeit.Timer.repeat" title="Permalink to this definition">¶</a></dt> <dd><p>Call <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a> a few times.</p> <p>This is a convenience function that calls the <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a> repeatedly, returning a list of results. The first argument specifies how many times to call <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a>. The second argument specifies the <em>number</em> argument for <a class="reference internal" href="#timeit.Timer.timeit" title="timeit.Timer.timeit"><tt class="xref py py-meth docutils literal"><span class="pre">timeit()</span></tt></a>.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">It’s tempting to calculate mean and standard deviation from the result vector and report these. However, this is not very useful. In a typical case, the lowest value gives a lower bound for how fast your machine can run the given code snippet; higher values in the result vector are typically not caused by variability in Python’s speed, but by other processes interfering with your timing accuracy. So the <a class="reference internal" href="functions.html#min" title="min"><tt class="xref py py-func docutils literal"><span class="pre">min()</span></tt></a> of the result is probably the only number you should be interested in. After that, you should look at the entire vector and apply common sense rather than statistics.</p> </div> </dd></dl> <dl class="method"> <dt id="timeit.Timer.print_exc"> <tt class="descname">print_exc</tt><big>(</big><em>file=None</em><big>)</big><a class="headerlink" href="#timeit.Timer.print_exc" title="Permalink to this definition">¶</a></dt> <dd><p>Helper to print a traceback from the timed code.</p> <p>Typical use:</p> <div class="highlight-python"><div class="highlight"><pre><span class="n">t</span> <span class="o">=</span> <span class="n">Timer</span><span class="p">(</span><span class="o">...</span><span class="p">)</span> <span class="c"># outside the try/except</span> <span class="k">try</span><span class="p">:</span> <span class="n">t</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="o">...</span><span class="p">)</span> <span class="c"># or t.repeat(...)</span> <span class="k">except</span><span class="p">:</span> <span class="n">t</span><span class="o">.</span><span class="n">print_exc</span><span class="p">()</span> </pre></div> </div> <p>The advantage over the standard traceback is that source lines in the compiled template will be displayed. The optional <em>file</em> argument directs where the traceback is sent; it defaults to <a class="reference internal" href="sys.html#sys.stderr" title="sys.stderr"><tt class="xref py py-data docutils literal"><span class="pre">sys.stderr</span></tt></a>.</p> </dd></dl> </dd></dl> </div> <div class="section" id="command-line-interface"> <span id="id2"></span><h2>26.6.3. Command-Line Interface<a class="headerlink" href="#command-line-interface" title="Permalink to this headline">¶</a></h2> <p>When called as a program from the command line, the following form is used:</p> <div class="highlight-python"><pre>python -m timeit [-n N] [-r N] [-s S] [-t] [-c] [-h] [statement ...]</pre> </div> <p>Where the following options are understood:</p> <dl class="cmdoption"> <dt id="cmdoption-timeit-n"> <tt class="descname">-n</tt><tt class="descclassname"> N</tt><tt class="descclassname">, </tt><tt class="descname">--number</tt><tt class="descclassname">=N</tt><a class="headerlink" href="#cmdoption-timeit-n" title="Permalink to this definition">¶</a></dt> <dd><p>how many times to execute ‘statement’</p> </dd></dl> <dl class="cmdoption"> <dt id="cmdoption-timeit-r"> <tt class="descname">-r</tt><tt class="descclassname"> N</tt><tt class="descclassname">, </tt><tt class="descname">--repeat</tt><tt class="descclassname">=N</tt><a class="headerlink" href="#cmdoption-timeit-r" title="Permalink to this definition">¶</a></dt> <dd><p>how many times to repeat the timer (default 3)</p> </dd></dl> <dl class="cmdoption"> <dt id="cmdoption-timeit-s"> <tt class="descname">-s</tt><tt class="descclassname"> S</tt><tt class="descclassname">, </tt><tt class="descname">--setup</tt><tt class="descclassname">=S</tt><a class="headerlink" href="#cmdoption-timeit-s" title="Permalink to this definition">¶</a></dt> <dd><p>statement to be executed once initially (default <tt class="docutils literal"><span class="pre">pass</span></tt>)</p> </dd></dl> <dl class="cmdoption"> <dt id="cmdoption-timeit-t"> <tt class="descname">-t</tt><tt class="descclassname"></tt><tt class="descclassname">, </tt><tt class="descname">--time</tt><tt class="descclassname"></tt><a class="headerlink" href="#cmdoption-timeit-t" title="Permalink to this definition">¶</a></dt> <dd><p>use <a class="reference internal" href="time.html#time.time" title="time.time"><tt class="xref py py-func docutils literal"><span class="pre">time.time()</span></tt></a> (default on all platforms but Windows)</p> </dd></dl> <dl class="cmdoption"> <dt id="cmdoption-timeit-c"> <tt class="descname">-c</tt><tt class="descclassname"></tt><tt class="descclassname">, </tt><tt class="descname">--clock</tt><tt class="descclassname"></tt><a class="headerlink" href="#cmdoption-timeit-c" title="Permalink to this definition">¶</a></dt> <dd><p>use <a class="reference internal" href="time.html#time.clock" title="time.clock"><tt class="xref py py-func docutils literal"><span class="pre">time.clock()</span></tt></a> (default on Windows)</p> </dd></dl> <dl class="cmdoption"> <dt id="cmdoption-timeit-v"> <tt class="descname">-v</tt><tt class="descclassname"></tt><tt class="descclassname">, </tt><tt class="descname">--verbose</tt><tt class="descclassname"></tt><a class="headerlink" href="#cmdoption-timeit-v" title="Permalink to this definition">¶</a></dt> <dd><p>print raw timing results; repeat for more digits precision</p> </dd></dl> <dl class="cmdoption"> <dt id="cmdoption-timeit-h"> <tt class="descname">-h</tt><tt class="descclassname"></tt><tt class="descclassname">, </tt><tt class="descname">--help</tt><tt class="descclassname"></tt><a class="headerlink" href="#cmdoption-timeit-h" title="Permalink to this definition">¶</a></dt> <dd><p>print a short usage message and exit</p> </dd></dl> <p>A multi-line statement may be given by specifying each line as a separate statement argument; indented lines are possible by enclosing an argument in quotes and using leading spaces. Multiple <a class="reference internal" href="#cmdoption-timeit-s"><em class="xref std std-option">-s</em></a> options are treated similarly.</p> <p>If <a class="reference internal" href="#cmdoption-timeit-n"><em class="xref std std-option">-n</em></a> is not given, a suitable number of loops is calculated by trying successive powers of 10 until the total time is at least 0.2 seconds.</p> <p><a class="reference internal" href="#timeit.default_timer" title="timeit.default_timer"><tt class="xref py py-func docutils literal"><span class="pre">default_timer()</span></tt></a> measurations can be affected by other programs running on the same machine, so the best thing to do when accurate timing is necessary is to repeat the timing a few times and use the best time. The <a class="reference internal" href="#cmdoption-timeit-r"><em class="xref std std-option">-r</em></a> option is good for this; the default of 3 repetitions is probably enough in most cases. On Unix, you can use <a class="reference internal" href="time.html#time.clock" title="time.clock"><tt class="xref py py-func docutils literal"><span class="pre">time.clock()</span></tt></a> to measure CPU time.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">There is a certain baseline overhead associated with executing a pass statement. The code here doesn’t try to hide it, but you should be aware of it. The baseline overhead can be measured by invoking the program without arguments, and it might differ between Python versions. Also, to fairly compare older Python versions to Python 2.3, you may want to use Python’s <em class="xref std std-option">-O</em> option for the older versions to avoid timing <tt class="docutils literal"><span class="pre">SET_LINENO</span></tt> instructions.</p> </div> </div> <div class="section" id="examples"> <span id="timeit-examples"></span><h2>26.6.4. Examples<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2> <p>It is possible to provide a setup statement that is executed only once at the beginning:</p> <div class="highlight-sh"><div class="highlight"><pre><span class="nv">$ </span>python -m timeit -s <span class="s1">'text = "sample string"; char = "g"'</span> <span class="s1">'char in text'</span> 10000000 loops, best of 3: 0.0877 usec per loop <span class="nv">$ </span>python -m timeit -s <span class="s1">'text = "sample string"; char = "g"'</span> <span class="s1">'text.find(char)'</span> 1000000 loops, best of 3: 0.342 usec per loop </pre></div> </div> <div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">timeit</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="s">'char in text'</span><span class="p">,</span> <span class="n">setup</span><span class="o">=</span><span class="s">'text = "sample string"; char = "g"'</span><span class="p">)</span> <span class="go">0.41440500499993504</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="s">'text.find(char)'</span><span class="p">,</span> <span class="n">setup</span><span class="o">=</span><span class="s">'text = "sample string"; char = "g"'</span><span class="p">)</span> <span class="go">1.7246671520006203</span> </pre></div> </div> <p>The same can be done using the <a class="reference internal" href="#timeit.Timer" title="timeit.Timer"><tt class="xref py py-class docutils literal"><span class="pre">Timer</span></tt></a> class and its methods:</p> <div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">timeit</span> <span class="gp">>>> </span><span class="n">t</span> <span class="o">=</span> <span class="n">timeit</span><span class="o">.</span><span class="n">Timer</span><span class="p">(</span><span class="s">'char in text'</span><span class="p">,</span> <span class="n">setup</span><span class="o">=</span><span class="s">'text = "sample string"; char = "g"'</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">t</span><span class="o">.</span><span class="n">timeit</span><span class="p">()</span> <span class="go">0.3955516149999312</span> <span class="gp">>>> </span><span class="n">t</span><span class="o">.</span><span class="n">repeat</span><span class="p">()</span> <span class="go">[0.40193588800002544, 0.3960157959998014, 0.39594301399984033]</span> </pre></div> </div> <p>The following examples show how to time expressions that contain multiple lines. Here we compare the cost of using <a class="reference internal" href="functions.html#hasattr" title="hasattr"><tt class="xref py py-func docutils literal"><span class="pre">hasattr()</span></tt></a> vs. <a class="reference internal" href="../reference/compound_stmts.html#try"><tt class="xref std std-keyword docutils literal"><span class="pre">try</span></tt></a>/<a class="reference internal" href="../reference/compound_stmts.html#except"><tt class="xref std std-keyword docutils literal"><span class="pre">except</span></tt></a> to test for missing and present object attributes:</p> <div class="highlight-sh"><div class="highlight"><pre><span class="nv">$ </span>python -m timeit <span class="s1">'try:'</span> <span class="s1">' str.__nonzero__'</span> <span class="s1">'except AttributeError:'</span> <span class="s1">' pass'</span> 100000 loops, best of 3: 15.7 usec per loop <span class="nv">$ </span>python -m timeit <span class="s1">'if hasattr(str, "__nonzero__"): pass'</span> 100000 loops, best of 3: 4.26 usec per loop <span class="nv">$ </span>python -m timeit <span class="s1">'try:'</span> <span class="s1">' int.__nonzero__'</span> <span class="s1">'except AttributeError:'</span> <span class="s1">' pass'</span> 1000000 loops, best of 3: 1.43 usec per loop <span class="nv">$ </span>python -m timeit <span class="s1">'if hasattr(int, "__nonzero__"): pass'</span> 100000 loops, best of 3: 2.23 usec per loop </pre></div> </div> <div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">timeit</span> <span class="gp">>>> </span><span class="c"># attribute is missing</span> <span class="gp">>>> </span><span class="n">s</span> <span class="o">=</span> <span class="s">"""</span><span class="se">\</span> <span class="gp">... </span><span class="s">try:</span> <span class="gp">... </span><span class="s"> str.__nonzero__</span> <span class="gp">... </span><span class="s">except AttributeError:</span> <span class="gp">... </span><span class="s"> pass</span> <span class="gp">... </span><span class="s">"""</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="n">stmt</span><span class="o">=</span><span class="n">s</span><span class="p">,</span> <span class="n">number</span><span class="o">=</span><span class="mi">100000</span><span class="p">)</span> <span class="go">0.9138244460009446</span> <span class="gp">>>> </span><span class="n">s</span> <span class="o">=</span> <span class="s">"if hasattr(str, '__bool__'): pass"</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="n">stmt</span><span class="o">=</span><span class="n">s</span><span class="p">,</span> <span class="n">number</span><span class="o">=</span><span class="mi">100000</span><span class="p">)</span> <span class="go">0.5829014980008651</span> <span class="go">>>></span> <span class="gp">>>> </span><span class="c"># attribute is present</span> <span class="gp">>>> </span><span class="n">s</span> <span class="o">=</span> <span class="s">"""</span><span class="se">\</span> <span class="gp">... </span><span class="s">try:</span> <span class="gp">... </span><span class="s"> int.__nonzero__</span> <span class="gp">... </span><span class="s">except AttributeError:</span> <span class="gp">... </span><span class="s"> pass</span> <span class="gp">... </span><span class="s">"""</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="n">stmt</span><span class="o">=</span><span class="n">s</span><span class="p">,</span> <span class="n">number</span><span class="o">=</span><span class="mi">100000</span><span class="p">)</span> <span class="go">0.04215312199994514</span> <span class="gp">>>> </span><span class="n">s</span> <span class="o">=</span> <span class="s">"if hasattr(int, '__bool__'): pass"</span> <span class="gp">>>> </span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="n">stmt</span><span class="o">=</span><span class="n">s</span><span class="p">,</span> <span class="n">number</span><span class="o">=</span><span class="mi">100000</span><span class="p">)</span> <span class="go">0.08588060699912603</span> </pre></div> </div> <p>To give the <a class="reference internal" href="#module-timeit" title="timeit: Measure the execution time of small code snippets."><tt class="xref py py-mod docutils literal"><span class="pre">timeit</span></tt></a> module access to functions you define, you can pass a <em>setup</em> parameter which contains an import statement:</p> <div class="highlight-python"><div class="highlight"><pre><span class="k">def</span> <span class="nf">test</span><span class="p">():</span> <span class="sd">"""Stupid test function"""</span> <span class="n">L</span> <span class="o">=</span> <span class="p">[]</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">100</span><span class="p">):</span> <span class="n">L</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">i</span><span class="p">)</span> <span class="k">if</span> <span class="n">__name__</span> <span class="o">==</span> <span class="s">'__main__'</span><span class="p">:</span> <span class="kn">import</span> <span class="nn">timeit</span> <span class="k">print</span><span class="p">(</span><span class="n">timeit</span><span class="o">.</span><span class="n">timeit</span><span class="p">(</span><span class="s">"test()"</span><span class="p">,</span> <span class="n">setup</span><span class="o">=</span><span class="s">"from __main__ import test"</span><span class="p">))</span> </pre></div> </div> </div> </div> </div> </div> </div> <div class="sphinxsidebar"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table Of Contents</a></h3> <ul> <li><a class="reference internal" href="#">26.6. <tt class="docutils literal"><span class="pre">timeit</span></tt> — Measure execution time of small code snippets</a><ul> <li><a class="reference internal" href="#basic-examples">26.6.1. Basic Examples</a></li> <li><a class="reference internal" href="#python-interface">26.6.2. Python Interface</a></li> <li><a class="reference internal" href="#command-line-interface">26.6.3. Command-Line Interface</a></li> <li><a class="reference internal" href="#examples">26.6.4. Examples</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="hotshot.html" title="previous chapter">26.5. <tt class="docutils literal"><span class="pre">hotshot</span></tt> — High performance logging profiler</a></p> <h4>Next topic</h4> <p class="topless"><a href="trace.html" title="next chapter">26.7. <tt class="docutils literal"><span class="pre">trace</span></tt> — Trace or track Python statement execution</a></p> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li><a href="../_sources/library/timeit.txt" rel="nofollow">Show Source</a></li> </ul> <div id="searchbox" style="display: none"> <h3>Quick search</h3> <form class="search" action="../search.html" method="get"> <input type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> <p class="searchtip" style="font-size: 90%"> Enter search terms or a module, class or function name. </p> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="trace.html" title="26.7. trace — Trace or track Python statement execution" >next</a> |</li> <li class="right" > <a href="hotshot.html" title="26.5. hotshot — High performance logging profiler" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="http://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.5 documentation</a> » </li> <li><a href="index.html" >The Python Standard Library</a> »</li> <li><a href="debug.html" >26. Debugging and Profiling</a> »</li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 1990-2019, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="http://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on Jul 03, 2019. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.1.3. </div> </body> </html>
💾 Save Changes
Cancel
📤 Upload File
×
Select File
Upload
Cancel
➕ Create New
×
Type
📄 File
📁 Folder
Name
Create
Cancel
✎ Rename Item
×
Current Name
New Name
Rename
Cancel
🔐 Change Permissions
×
Target File
Permission (e.g., 0755, 0644)
0755
0644
0777
Apply
Cancel