title: ImportError: No module named cv2 in ubuntu 16.04 Anaconda2
body: <p>I know this is a common problem but I tried all method first.</p>
  
  <p>The following shows the problem and what I have tried:</p>
  
  <pre><code>$ python
  Python 2.7.13 |Anaconda 4.3.0 (64-bit)| (default, Dec 20 2016, 23:09:15) 
  [GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  Anaconda is brought to you by Continuum Analytics.
  Please check out: http://continuum.io/thanks and https://anaconda.org
  &gt;&gt;&gt; import caffe
  &gt;&gt;&gt; import cv2
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  ImportError: No module named cv2
  &gt;&gt;&gt; import numpy
  &gt;&gt;&gt; print numpy.__version__
  1.11.3
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>The method I have tried:
  1. confirmed numpy version;</p>
  
  <ol start="2">
  <li><p>Confirm python version is 2.7</p></li>
  <li><p>check opencv version;</p></li>
  </ol>
  
  <p>$ dpkg -l | grep libopencv</p>
  
  <ol start="4">
  <li>Install opencv by 
  $conda install -c menpo opencv=2.4.11</li>
  </ol>
  
  <p>After step 4 above, cv2 could be imported appropriately but fail to import Caffe. The caffe installation was implemented before and it passed all the check. Like 'make all'; 'make runtest'; and 'make pycaffee'. Now it failed in 'make all' also 'make pycaffee'. So here it is error message:</p>
  
  <pre><code>$ python 
  Python 2.7.13 |Anaconda 4.3.0 (64-bit)| (default, Dec 20 2016, 23:09:15) 
  [GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  Anaconda is brought to you by Continuum Analytics.
  Please check out: http://continuum.io/thanks and https://anaconda.org
  &gt;&gt;&gt; import cv2
  &gt;&gt;&gt; import caffe
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/home/cocadas/Program/caffe-master/python/caffe/__init__.py", line 1, in &lt;module&gt;
      from .pycaffe import Net, SGDSolver, NesterovSolver, AdaGradSolver, RMSPropSolver, AdaDeltaSolver, AdamSolver, NCCL, Timer
    File "/home/cocadas/Program/caffe-master/python/caffe/pycaffe.py", line 13, in &lt;module&gt;
      from ._caffe import Net, SGDSolver, NesterovSolver, AdaGradSolver, \
  ImportError: No module named _caffe
  &gt;&gt;&gt; exit()
  </code></pre>
  
  <p>The following is the conda list.</p>
  
  <pre><code>$ conda list
  # packages in environment at /home/cocadas/anaconda2:
  #
  _license                  1.1                      py27_1  
  alabaster                 0.7.9                    py27_0  
  anaconda                  4.3.0               np111py27_0  
  anaconda-client           1.6.0                    py27_0  
  anaconda-navigator        1.4.3                    py27_0  
  argcomplete               1.0.0                    py27_1  
  astroid                   1.4.9                    py27_0  
  astropy                   1.3                 np111py27_0  
  babel                     2.3.4                    py27_0  
  backports                 1.0                      py27_0  
  backports_abc             0.5                      py27_0  
  beautifulsoup4            4.5.3                    py27_0  
  bitarray                  0.8.1                    py27_0  
  blaze                     0.10.1                   py27_0  
  bokeh                     0.12.4                   py27_0  
  boto                      2.45.0                   py27_0  
  bottleneck                1.2.0               np111py27_0  
  bzip2                     1.0.6                         3  
  cairo                     1.14.8                        0  
  cdecimal                  2.3                      py27_2  
  cffi                      1.9.1                    py27_0  
  chardet                   2.3.0                    py27_0  
  chest                     0.2.3                    py27_0  
  click                     6.7                      py27_0  
  cloudpickle               0.2.2                    py27_0  
  clyent                    1.2.2                    py27_0  
  cmake                     3.6.3                         0  
  colorama                  0.3.7                    py27_0  
  conda                     4.3.14                   py27_0  
  conda-build               2.1.7                    py27_0  
  conda-env                 2.6.0                         0  
  conda-verify              2.0.0                    py27_0  
  configobj                 5.0.6                    py27_0  
  configparser              3.5.0                    py27_0  
  contextlib2               0.5.4                    py27_0  
  cryptography              1.7.1                    py27_0  
  curl                      7.52.1                        0  
  cycler                    0.10.0                   py27_0  
  cython                    0.25.2                   py27_0  
  cytoolz                   0.8.2                    py27_0  
  dask                      0.13.0                   py27_0  
  datashape                 0.5.4                    py27_0  
  dbus                      1.10.10                       0  
  decorator                 4.0.11                   py27_0  
  dill                      0.2.5                    py27_0  
  dlib                      19.4.0                    &lt;pip&gt;
  docutils                  0.13.1                   py27_0  
  entrypoints               0.2.2                    py27_0  
  enum34                    1.1.6                    py27_0  
  et_xmlfile                1.0.1                    py27_0  
  expat                     2.1.0                         0  
  fastcache                 1.0.2                    py27_1  
  filelock                  2.0.7                    py27_0  
  flask                     0.12                     py27_0  
  flask-cors                3.0.2                    py27_0  
  fontconfig                2.12.1                        2  
  freetype                  2.5.5                         2  
  funcsigs                  1.0.2                    py27_0  
  functools32               3.2.3.2                  py27_0  
  futures                   3.0.5                    py27_0  
  get_terminal_size         1.0.0                    py27_0  
  gevent                    1.2.1                    py27_0  
  glib                      2.50.2                        1  
  greenlet                  0.4.11                   py27_0  
  grin                      1.2.1                    py27_3  
  gst-plugins-base          1.8.0                         0  
  gstreamer                 1.8.0                         0  
  h5py                      2.6.0               np111py27_2  
  harfbuzz                  0.9.39                        2  
  hdf5                      1.8.17                        1  
  heapdict                  1.0.0                    py27_1  
  icu                       54.1                          0  
  idna                      2.2                      py27_0  
  imagesize                 0.7.1                    py27_0  
  ipaddress                 1.0.18                   py27_0  
  ipykernel                 4.5.2                    py27_0  
  ipython                   5.1.0                    py27_0  
  ipython_genutils          0.1.0                    py27_0  
  ipywidgets                5.2.2                    py27_1  
  isort                     4.2.5                    py27_0  
  itsdangerous              0.24                     py27_0  
  jbig                      2.1                           0  
  jdcal                     1.3                      py27_0  
  jedi                      0.9.0                    py27_1  
  jinja2                    2.9.4                    py27_0  
  jpeg                      9b                            0  
  jsonschema                2.5.1                    py27_0  
  jupyter                   1.0.0                    py27_3  
  jupyter_client            4.4.0                    py27_0  
  jupyter_console           5.0.0                    py27_0  
  jupyter_core              4.2.1                    py27_0  
  lazy-object-proxy         1.2.2                    py27_0  
  leveldb                   0.194                     &lt;pip&gt;
  libffi                    3.2.1                         1  
  libgcc                    4.8.5                         2  
  libgfortran               3.0.0                         1  
  libiconv                  1.14                          0  
  libpng                    1.6.27                        0  
  libsodium                 1.0.10                        0  
  libtiff                   4.0.6                         3  
  libxcb                    1.12                          1  
  libxml2                   2.9.4                         0  
  libxslt                   1.1.29                        0  
  llvmlite                  0.15.0                   py27_0  
  locket                    0.2.0                    py27_1  
  lxml                      3.7.2                    py27_0  
  markupsafe                0.23                     py27_2  
  matplotlib                2.0.0               np111py27_0  
  mistune                   0.7.3                    py27_0  
  mkl                       2017.0.1                      0  
  mkl-service               1.1.2                    py27_3  
  mpmath                    0.19                     py27_1  
  multipledispatch          0.4.9                    py27_0  
  nbconvert                 4.2.0                    py27_0  
  nbformat                  4.2.0                    py27_0  
  ncurses                   5.9                          10  
  networkx                  1.11                     py27_0  
  nltk                      3.2.2                    py27_0  
  nose                      1.3.7                    py27_1  
  notebook                  4.3.1                    py27_0  
  numba                     0.30.1              np111py27_0  
  numexpr                   2.6.1               np111py27_2  
  numpy                     1.11.3                   py27_0  
  numpydoc                  0.6.0                    py27_0  
  odo                       0.5.0                    py27_1  
  olefile                   0.44                      &lt;pip&gt;
  opencv                    2.4.11                 nppy27_0    menpo
  openpyxl                  2.4.1                    py27_0  
  openssl                   1.0.2k                        0  
  pandas                    0.19.2              np111py27_1  
  partd                     0.3.7                    py27_0  
  patchelf                  0.9                           0  
  path.py                   10.0                     py27_0  
  pathlib2                  2.2.0                    py27_0  
  patsy                     0.4.1                    py27_0  
  pcre                      8.39                          1  
  pep8                      1.7.0                    py27_0  
  pexpect                   4.2.1                    py27_0  
  pickleshare               0.7.4                    py27_0  
  pillow                    4.0.0                    py27_0  
  pip                       9.0.1                    py27_1  
  pixman                    0.34.0                        0  
  pkginfo                   1.4.1                    py27_0  
  ply                       3.9                      py27_0  
  prompt_toolkit            1.0.9                    py27_0  
  protobuf                  3.2.0                     &lt;pip&gt;
  psutil                    5.0.1                    py27_0  
  ptyprocess                0.5.1                    py27_0  
  py                        1.4.32                   py27_0  
  pyasn1                    0.1.9                    py27_0  
  pycairo                   1.10.0                   py27_0  
  pycosat                   0.6.1                    py27_1  
  pycparser                 2.17                     py27_0  
  pycrypto                  2.6.1                    py27_4  
  pycurl                    7.43.0                   py27_2  
  pyflakes                  1.5.0                    py27_0  
  pygments                  2.1.3                    py27_0  
  pylint                    1.6.4                    py27_1  
  pyopenssl                 16.2.0                   py27_0  
  pyparsing                 2.1.4                    py27_0  
  pyqt                      5.6.0                    py27_2  
  pytables                  3.3.0               np111py27_0  
  pytest                    3.0.5                    py27_0  
  python                    2.7.13                        0  
  python-dateutil           1.5                       &lt;pip&gt;
  python-dateutil           2.6.0                    py27_0  
  python-gflags             3.1.1                     &lt;pip&gt;
  pytz                      2016.10                  py27_0  
  pyyaml                    3.12                     py27_0  
  pyzmq                     16.0.2                   py27_0  
  qt                        5.6.2                         3  
  qtawesome                 0.4.3                    py27_0  
  qtconsole                 4.2.1                    py27_1  
  qtpy                      1.2.1                    py27_0  
  readline                  6.2                           2  
  redis                     3.2.0                         0  
  redis-py                  2.10.5                   py27_0  
  requests                  2.12.4                   py27_0  
  rope                      0.9.4                    py27_1  
  ruamel_yaml               0.11.14                  py27_1  
  scandir                   1.4                      py27_0  
  scikit-image              0.12.3              np111py27_1  
  scikit-learn              0.18.1              np111py27_1  
  scipy                     0.18.1              np111py27_1  
  seaborn                   0.7.1                    py27_0  
  setuptools                27.2.0                   py27_0  
  simplegeneric             0.8.1                    py27_1  
  singledispatch            3.4.0.3                  py27_0  
  sip                       4.18                     py27_0  
  six                       1.10.0                   py27_0  
  snowballstemmer           1.2.1                    py27_0  
  sockjs-tornado            1.0.3                    py27_0  
  sphinx                    1.5.1                    py27_0  
  spyder                    3.1.2                    py27_0  
  sqlalchemy                1.1.5                    py27_0  
  sqlite                    3.13.0                        0  
  ssl_match_hostname        3.4.0.2                  py27_1  
  statsmodels               0.6.1               np111py27_1  
  subprocess32              3.2.7                    py27_0  
  sympy                     1.0                      py27_0  
  terminado                 0.6                      py27_0  
  tk                        8.5.18                        0  
  toolz                     0.8.2                    py27_0  
  tornado                   4.4.2                    py27_0  
  traitlets                 4.3.1                    py27_0  
  unicodecsv                0.14.1                   py27_0  
  wcwidth                   0.1.7                    py27_0  
  werkzeug                  0.11.15                  py27_0  
  wheel                     0.29.0                   py27_0  
  widgetsnbextension        1.2.6                    py27_0  
  wrapt                     1.10.8                   py27_0  
  xgboost                   0.6a2                     &lt;pip&gt;
  xlrd                      1.0.0                    py27_0  
  xlsxwriter                0.9.6                    py27_0  
  xlwt                      1.2.0                    py27_0  
  xz                        5.2.2                         1  
  yaml                      0.1.6                         0  
  zeromq                    4.1.5                         0  
  zlib                      1.2.8                         3  
  </code></pre>
  
  <p>Error message of compiling caffe after installing cv2 in conda.</p>
  
  <pre><code>$make clean
  $make all
  ...
  AR -o .build_release/lib/libcaffe.a
  LD -o .build_release/lib/libcaffe.so.1.0.0-rc5
  /usr/bin/ld: cannot find -ltbb
  collect2: error: ld returned 1 exit status
  Makefile:574: recipe for target '.build_release/lib/libcaffe.so.1.0.0-rc5' failed
  make: *** [.build_release/lib/libcaffe.so.1.0.0-rc5] Error 1
  </code></pre>
  
  <p>Error message of making pycaffe</p>
  
  <pre><code>$ make pycaffe
  LD -o .build_release/lib/libcaffe.so.1.0.0-rc5
  /usr/bin/ld: cannot find -ltbb
  collect2: error: ld returned 1 exit status
  Makefile:574: recipe for target '.build_release/lib/libcaffe.so.1.0.0-rc5' failed
  make: *** [.build_release/lib/libcaffe.so.1.0.0-rc5] Error 1
  cocadas@cocadas-ThinkPad-W540:~/Program/caffe-master$ 
  </code></pre>
  
  <p>Since it is lack of ltbb, I install the package</p>
  
  <pre><code>$sudo apt-get install libtbb-dev
  </code></pre>
  
  <p>Then the problem of 'can't find -ltbb' goes away. But then it complains on the </p>
  
  <pre><code>.build_release/lib/libcaffe.so: undefined reference to `cv::imread(cv::String const&amp;, int)'
  .build_release/lib/libcaffe.so: undefined reference to `cv::imencode(cv::String const&amp;, cv::_InputArray const&amp;, std::vector&lt;unsigned char, std::allocator&lt;unsigned char&gt; &gt;&amp;, std::vector&lt;int, std::allocator&lt;int&gt; &gt; const&amp;)'
  .build_release/lib/libcaffe.so: undefined reference to `cv::imdecode(cv::_InputArray const&amp;, int)'
  </code></pre>