I had to use the `install` function instead:

    conda install pandas=0.13.1

For the case that you wish to revert a recently installed package that made several changes to dependencies (such as tensorflow), you can &quot;roll back&quot; to an earlier installation state via the following method:


    conda list --revisions
    conda install --revision [revision number]


The first command shows previous installation revisions (with dependencies) and the second reverts to whichever `revision number` you specify.

Note that if you wish to (re)install a later revision, you may have to sequentially reinstall all intermediate versions.  If you had been at revision 23, reinstalled revision 20 and wish to return, you may have to run each:

    conda install --revision 21
    conda install --revision 22
    conda install --revision 23

I know it was not available at the time, but now you could also use Anaconda navigator to install a specific version of packages in the environments tab.

Compiling this:

    #include &lt;iostream&gt;
     
    int main()
    {
    	for (int i = 0; i &lt; 4; ++i)
    		std::cout &lt;&lt; i*1000000000 &lt;&lt; std::endl;
    }

and `gcc` produces the following warning:

    warning: iteration 3u invokes undefined behavior [-Waggressive-loop-optimizations]
       std::cout &lt;&lt; i*1000000000 &lt;&lt; std::endl;
                      ^

I understand there is a signed integer overflow.

What I cannot get is why `i` value is broken by that overflow operation?

I&#39;ve read the answers to https://stackoverflow.com/questions/7682477/why-does-integer-overflow-on-x86-with-gcc-cause-an-infinite-loop, but I&#39;m still not clear on *why* this happens - I get that &quot;undefined&quot; means &quot;anything can happen&quot;, but what&#39;s the underlying cause of *this specific behavior*?

Online: http://ideone.com/dMrRKR

Compiler: `gcc (4.8)`

Why does this loop produce &quot;warning: iteration 3u invokes undefined behavior&quot; and output more than 4 lines?

Is there a standard functional interface in the JDK that takes nothing and returns nothing? I cannot find one. Something like the following:

    @FunctionalInterface
    interface Action {
      void execute();
    }



functional interface that takes nothing and returns nothing

If I do 

    conda info pandas

I can see all of the packages available.

I updated my `pandas` to the latest this morning, but I need to revert to a prior version now. I tried

    conda update pandas 0.13.1

but that didn&#39;t work. How do I specify which version to use?

How do I revert to a previous package in Anaconda?

If I do
<pre><code class="hljs">conda info pandas
</code></pre>
I can see all of the packages available.
I updated my <code>pandas</code> to the latest this morning, but I need to revert to a prior version now. I tried
<pre><code class="hljs language-sql">conda update pandas 0.13.1
</code></pre>
but that didn't work. How do I specify which version to use?

I am trying to write a paper in IPython notebook, but encountered some issues with display format. Say I have following dataframe `df`, is there any way to format `var1` and `var2` into 2 digit decimals and `var3` into percentages.

	       var1	       var2         var3	
    id												
    0	 1.458315	 1.500092	-0.005709	
    1	 1.576704	 1.608445	-0.005122	 
    2	 1.629253	 1.652577	-0.004754	 
    3	 1.669331	 1.685456	-0.003525	
    4	 1.705139	 1.712096	-0.003134	
    5	 1.740447	 1.741961	-0.001223	
    6	 1.775980	 1.770801	-0.001723	 
    7	 1.812037	 1.799327	-0.002013	 
    8	 1.853130	 1.822982	-0.001396	 
    9	 1.943985	 1.868401	 0.005732

The numbers inside are not multiplied by 100, e.g.  -0.0057=-0.57%.

Format certain floating dataframe columns into percentage in pandas

Lots of other threads about similar issues, but none that I could find where quite the same case as mine. So, here goes:

**Things I did:**

 - Ran: `sudo easy_install pip`
 - Ran: `sudo pip install virtualenv`
 - Ran: `sudo pip install virtualenvwrapper`

**Current State:**

 - .bash_profile

        export PATH=/usr/local/bin:$PATH
        export PIP_DOWNLOAD_CACHE=$HOME/.pip/cache
        export WORKON_HOME=$HOME/.virtualenvs
        export PIP_VIRTUALENV_BASE=$WORKON_HOME
        export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python

 - Running `mkvirtualenv test` results in:

        New python executable in trunk/bin/python
        Installing setuptools, pip...done.
        /usr/bin/python: No module named virtualenvwrapper

 - Manually inspecting &#39;/usr/local/bin&#39; shows that virtualenvwrapper.sh exists
 - Unlike some other questions I saw about this, I get no message about virtualenvwrapper when I start a new terminal window
 - Running &#39;which python&#39; results in: `/usr/bin/python`


**What I&#39;ve tried:**

 - Inspecting my path to make sure it looks like it is supposed to
 - Reinstalling pip, then using the reinstalled pip to reinstall virtualenv and virtualenvwrapper



Any help getting this working would be very much appreciated.

Installed virtualenv and virtualenvwrapper: Python says no module named virtualenvwrapper

Noticed a line in our codebase today which I thought surely would have failed the build with syntax error, but tests were passing so apparently it was actually valid python (in both 2.x and 3).  

Whitespace is sometimes not required in the conditional expression:

    &gt;&gt;&gt; 1if True else 0
    1

It doesn&#39;t work if the LHS is a variable:

    &gt;&gt;&gt; x = 1
    &gt;&gt;&gt; xif True else 0
      File &quot;&lt;stdin&gt;&quot;, line 1
        xif True else 0
               ^
    SyntaxError: invalid syntax

But it does seem to still work with other types of literals:

    &gt;&gt;&gt; {&#39;hello&#39;}if False else &#39;potato&#39;
    &#39;potato&#39;

What&#39;s going on here, is it intentionally part of the grammar for some reason?  Is this odd quirk a known/documented behaviour?

Why isn&#39;t this a syntax error in python?

I&#39;d like to programmatically exit a cell early in IPython Notebook. `exit(0)`, however, kills the kernel. 

Whats the proper way to do this? I&#39;d prefer not to split the cell or manually halt execution. 

IPython Notebook - early exit from cell

What are the differences of these three static url? 

I am not sure if I am right, I am using the `MEDIA_ROOT` to store my uploaded photos (via `models.ImageField()`) 

However, I created a JS script to my admin and in `admin.py`. I defined the media as below:
   
    ....
    class Media:
          js = (&#39;/admin/custom.js&#39;, )

and my `settings.py`:

     ....
     STATIC_ROOT = &quot;/home/user/project/django1/top/listing/static&quot;

and I added the `custom.js` to `STATIC_ROOT/admin/custom.js`, but it is not working. Throwing 404 not found error. 

And then I change the `STATIC_ROOT` to `STATICFILES_DIRS`, and it works!!

    ....
    STATICFILES_DIRS = &quot;/home/user/project/django1/top/listing/static&quot;

So, I am not understand what is going on here. In fact, I just don&#39;t understand what is the difference between `STATIC_ROOT` and `STATICFILES_DIRS`. 

Currently I am testing Django in my machine via virtualenv, not deployed yet, is it the reason `STATIC_ROOT` not working?? 


Differences between STATICFILES_DIR, STATIC_ROOT and MEDIA_ROOT

I&#39;m relatively new in Mac OS. I&#39;ve just installed XCode (for c++ compiler) and Anaconda with the latest Python 3 (for myself). Now I&#39;m wondering how to install properly second Anaconda (for work) with Python 2?

I need both versions to work with iPython and Spyder IDE. Ideal way is to have totally separate Python environments. For example, I wish I could write like `conda install scikit-learn` for Python 3 environment and something like `conda2 install scikit-learn` for Python 2. 

How to install 2 Anacondas (Python 2 and 3) on Mac OS

I recently installed the Anaconda version of Python. Now when I type `python` into the terminal it opens the Anaconda distribution rather than the default distribution. How do I get it to use the default version for the command `python` on Linux ([Ubuntu&amp;nbsp;12.04][1] (Precise&amp;nbsp;Pangolin))?

  [1]: https://en.wikipedia.org/wiki/Ubuntu_version_history#Ubuntu_12.04_LTS_.28Precise_Pangolin.29


Use the default Python rather than the Anaconda installation when called from the terminal

I am setting up calls to python (Anaconda distribution) via BAT files and the windows task scheduler. 

I&#39;ve now used environments for the first time and was trying to set a `.bat` file up as below: 

    activate [my_env]
    python my_script.py
    deactivate

Unfortunately it appears that the second command does not get executed.

Conda environments and .BAT files

Is there a way (using conda update) that I can list outdated packages and select or bulk update (compatible) packages in Anaconda?

It doesn&#39;t make much sense updating the packages individually as there are hundreds of them.

Bulk package updates using Conda

I changed from Win XP 32bit to Win7 64bit and reinstalled Python 2.7
and the Anaconda package. 

However, it seems like it isn&#39;t properly installed.
When I do 

    import enum 

There is the error:

    ImportError: No module named enum

However, when I try import pandas it works.

When typing help() and modules within Ipython nothing happens.

Any idea how to go from here?

ImportError: No module named enum

I&#39;ve got Pycharm 4 running on my Linux (Ubuntu 14.04) machine.  In addition to the system python, I&#39;ve also got Anaconda installed.  Getting the two to play nicely together seems to be a bit of a problem... PyCharm provides some interesting integration for `virtualenv`s and `pip`, but the Anaconda Python distribution seems to prefer using its own `conda` tool for both activities.

Is there a relatively simple/painless way to be able to use `conda` in conjunction with PyCharm?  Not just as an alternative interpreter i.e. point PyCharm at the Anaconda Python binary for a project interpreter, but to be able to create, source/activate and deactivate virtual envs, add/remove packages in those virtual envs, etc. 

Or am I going to have to choose between using Anaconda (and having a more recent and up-to-date python than may come with the system), and being able to use PyCharm&#39;s features to their fullest extent?

Using (Ana)conda within PyCharm

I&#39;ve installed Anaconda and created two extra environments: py3k (which holds Python 3.3) and py34 (which holds Python 3.4). Besides those, I have a default environment named &#39;root&#39; which the Anaconda installer created by default and which holds Python 2.7. This last one is the default, whenever I launch &#39;ipython&#39; from the terminal it gives me version 2.7. In order to work with Python 3.4, I need to issue the commands (in the shell)

    source activate py34
    ipython

which change the default environment to Python 3.4. This works fine, but it&#39;s annoying since most of the time I work on Python 3.4, instead of Python 2.7 (which I hold for teaching purposes, it&#39;s a rather long story). Anyway, I&#39;ll like to know how to change the default environment to Python 3.4, bearing in mind that I don&#39;t want to reinstall everything from scratch.  



How to change default Anaconda python environment

I installed the latest version of Anaconda.
Now I want to install OpenCV within it. When I type:

    conda install -c https://conda.binstar.org/anaconda opencv

I get this message error: &quot;*conda is not recognized as internal command ...*&quot; (sorry, I try to translate from French because my OS is in French) 

The problem is that conda comes with Anaconda, so I wonder why lauching Anaconda and type the above command does not work ?

Content Type	Original Author	Original Content on Stackoverflow
Question	chrisaycock	View Question on Stackoverflow
Solution 1 - Python	chrisaycock	View Answer on Stackoverflow
Solution 2 - Python	anon01	View Answer on Stackoverflow
Solution 3 - Python	Szèles Àron	View Answer on Stackoverflow

How do I revert to a previous package in Anaconda?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

functional interface that takes nothing and returns nothing

Why does this loop produce "warning: iteration 3u invokes undefined behavior" and output more than 4 lines?

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