title: Numexpr not found in pandas
body: <p>I install numexpr package via pip on my Windows 7 machine:</p>
  
  <pre><code>pip list | grep numexpr
  numexpr (2.4.6)
  </code></pre>
  
  <p>but when I open ipython and trying to use <a href="http://pandas.pydata.org/pandas-docs/version/0.17.0/generated/pandas.DataFrame.query.html" rel="nofollow">df.query</a> it shows an error:</p>
  
  <pre><code>ImportError: 'numexpr' not found. Cannot use engine='numexpr' for query/eval if 'numexpr' is not installed
  </code></pre>
  
  <p>Than I checked whether it installed or not with pd.show_versions:</p>
  
  <pre><code>In [97]: pd.show_versions()
  
  INSTALLED VERSIONS
  ------------------
  commit: None
  python: 3.4.3.final.0
  python-bits: 32
  OS: Windows
  OS-release: 7
  machine: AMD64
  processor: Intel64 Family 6 Model 37 Stepping 5, GenuineIntel
  byteorder: little
  LC_ALL: None
  LANG: None
  
  pandas: 0.17.1
  nose: None
  pip: 7.1.2
  setuptools: 18.5
  Cython: None
  numpy: 1.10.1
  scipy: 0.16.1
  statsmodels: 0.6.1
  IPython: 4.0.0
  sphinx: None
  patsy: 0.4.1
  dateutil: 2.4.2
  pytz: 2015.7
  blosc: None
  bottleneck: 1.0.0
  tables: None
  numexpr: None
  matplotlib: 1.5.0
  openpyxl: 2.3.1
  xlrd: 0.9.4
  xlwt: 1.0.0
  xlsxwriter: None
  lxml: 3.5.0
  bs4: 4.4.1
  html5lib: 1.0b8
  httplib2: None
  apiclient: None
  sqlalchemy: None
  pymysql: None
  psycopg2: None
  Jinja2: 2.8
  </code></pre>
  
  <p>From the <a href="http://pandas.pydata.org/pandas-docs/version/0.17.0/install.html#dependencies" rel="nofollow">docs</a>:</p>
  
  <blockquote>
    <p><strong>numexpr</strong>: for accelerating certain numerical operations. numexpr uses multiple cores as well as smart chunking and caching to achieve large speedups. If installed, must be <strong>Version 2.1 or higher</strong>.</p>
  </blockquote>