The virtual environment manages files which *aren&#39;t* yours. It doesn&#39;t care how you manage your own files. Put them wherever makes sense to you, just not anywhere inside the venv directory tree. Common solutions include directly in `myproject`, or in `myproject/src`.

I guess you misunderstood the term &quot;Virtual Environment&quot;. It provides an isolated environment wherein you can download a different version of python packages and run it for your project. Hence, do not put anything inside your virtual environment. Keep it clean.

To take advantage of the virtual environment, 

 - activate it (source path_to_virtual_env/bin/activate )
 - install the necessary python packages using pip (pip install XYZ)
 - and run your python code using python command (python3 mycode.py)

I&#39;m trying to create an Angular 6 library and use it in an Angular 6 app. I&#39;ve boiled it down to a minimal test case. (Update: since Angular 7 is out, I&#39;ve tried that as well.)



&lt;!-- language: lang-bash --&gt;

    ng new workspace # accept the defaults
    ng new product # accept the defaults
    cd workspace 
    ng generate library widgets 
    ng build --prod widgets # leave out &quot;--prod&quot; for Angular 7
    cd ../product
    ng build

An app called &quot;workspace&quot; hosts a library called &quot;widgets&quot;. Another app called &quot;product&quot; stands alone. Everything to this point is fine.

Now let&#39;s try using the &quot;widgets&quot; library in the &quot;product&quot; app. Open the file `product/src/app/app.module.ts` which was generated by the CLI. Add two lines as shown below.  

&lt;!-- language: lang-js --&gt;

    import { BrowserModule } from &#39;@angular/platform-browser&#39;;
    import { NgModule } from &#39;@angular/core&#39;;
    
    import { AppComponent } from &#39;./app.component&#39;;
    import { WidgetsModule } from &#39;../../../workspace/dist/widgets&#39;; //  added
    
    @NgModule({
      declarations: [
        AppComponent
      ],
      imports: [
        BrowserModule,
        WidgetsModule // added
      ],
      providers: [],
      bootstrap: [AppComponent]
    })
    export class AppModule { }

After that change, when I run `ng build` from the product directory, I get warnings from Webpack.

    Date: 2018-07-31T13:13:08.001Z
    Hash: 8a6f58d2ae959edb3cc8
    Time: 8879ms
    chunk {main} main.js, main.js.map (main) 15.9 kB [initial] [rendered]
    chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 227 kB [initial] [rendered]
    chunk {runtime} runtime.js, runtime.js.map (runtime) 5.22 kB [entry] [rendered]
    chunk {styles} styles.js, styles.js.map (styles) 15.6 kB [initial] [rendered]
    chunk {vendor} vendor.js, vendor.js.map (vendor) 4.59 MB [initial] [rendered]
    
    WARNING in ../workspace/node_modules/@angular/core/fesm5/core.js
    4997:15-36 Critical dependency: the request of a dependency is an expression
    
    WARNING in ../workspace/node_modules/@angular/core/fesm5/core.js
    5009:15-102 Critical dependency: the request of a dependency is an expression

What does &quot;the result of a dependency is an expression&quot; mean? What am I doing wrong?





Angular 6 / 7 &quot;the result of a dependency is an expression&quot;

After some searching I failed to find a thorough comparison of `fastparquet` and `pyarrow`.

I found this blog [post][1] (a basic comparison of speeds). 

and a github [discussion][2] that claims that files created with `fastparquet` do not support  AWS-athena (btw is it still the case?)

when/why would I use one over the other? what are the major advantages and disadvantages ?

----

my specific use case is processing data with [`dask`][3] writing it to s3 and then reading/analyzing it with AWS-athena.


  [1]: http://wesmckinney.com/blog/python-parquet-update/
  [2]: https://github.com/dask/fastparquet/issues/150#issuecomment-313466287
  [3]: https://dask.pydata.org/en/latest/

A comparison between fastparquet and pyarrow?

(*Probably a noob question, but I didn&#39;t find a solution after googling for 20 minutes.*)

I created a new *pure Python* project with PyCharm which yielded the following folder structure

    myproject
    └── venv
        ├── bin
        │&#160;&#160; ├── activate
        │&#160;&#160; ├── activate.csh
        │&#160;&#160; ├── activate.fish
        │&#160;&#160; ├── easy_install
        │&#160;&#160; ├── easy_install-3.5
        │&#160;&#160; ├── pip
        │&#160;&#160; ├── pip3
        │&#160;&#160; ├── pip3.5
        │&#160;&#160; ├── python
        │&#160;&#160; ├── python3
        │&#160;&#160; └── python3.5
        ├── include
        ├── lib
        │&#160;&#160; └── python3.5
        ├── lib64 -&gt; lib
        └── pyvenv.cfg

Where do I put `myproject.py` or the `myproject` folder now?

- Inside or outside of `venv`?
- In the `venv/bin`folder?
- Just inside `venv`, i.e. `myproject/venv/myproject.py`?

Where do I put my python files in the venv folder?

(Probably a noob question, but I didn't find a solution after googling for 20 minutes.)
I created a new pure Python project with PyCharm which yielded the following folder structure
<pre><code class="hljs language-vbnet">myproject
└── venv
 ├── bin
 │   ├── activate
 │   ├── activate.csh
 │   ├── activate.fish
 │   ├── easy_install
 │   ├── easy_install-3.5
 │   ├── pip
 │   ├── pip3
 │   ├── pip3.5
 │   ├── python
 │   ├── python3
 │   └── python3.5
 ├── include
 ├── lib
 │   └── python3.5
 ├── lib64 -> lib
 └── pyvenv.cfg
</code></pre>
Where do I put <code>myproject.py</code> or the <code>myproject</code> folder now?
<ul>
<li>Inside or outside of <code>venv</code>?</li>
<li>In the <code>venv/bin</code>folder?</li>
<li>Just inside <code>venv</code>, i.e. <code>myproject/venv/myproject.py</code>?</li>
</ul>

Inputting the command `0xbin()` returns False:

    &gt;&gt;&gt; 0xbin()
    False

Why does that happen? This syntax should have no meaning whatsoever. Functions cannot start with 0, there are no &quot;i&quot; and &quot;n&quot; in hex, and the bin function must have some arguments.

In python, why does 0xbin() return False?

I created two lists `l1` and `l2`, but each one with a different creation method:

    import sys
    
    l1 = [None] * 10
    l2 = [None for _ in range(10)]
    
    print(&#39;Size of l1 =&#39;, sys.getsizeof(l1))
    print(&#39;Size of l2 =&#39;, sys.getsizeof(l2))

But the output surprised me:

    Size of l1 = 144
    Size of l2 = 192

The list created with a list comprehension is a bigger size in memory, but the two lists are identical in Python otherwise.

Why is that? Is this some CPython internal thing, or some other explanation?

Why do two identical lists have a different memory footprint?

I am using [`pipenv`](https://pipenv.kennethreitz.org/) to handle Python package dependencies.

The Python package is using two packages (named `pckg1` and `pckg2`) that rely on the same package named `pckg3`, **but from two different versions**. Showing the dependency tree :

    $ pipenv graph
      pckg1==3.0.0
        - pckg3 [required: &gt;=4.1.0]
      pckg2==1.0.2
        - pckg3 [required: ==4.0.11]

An attempt to install dependencies :

    $ pipenv install

    Warning: Your dependencies could not be resolved. You likely have a mismatch in your sub-dependencies.
    You can use $ pipenv install --skip-lock to bypass this mechanism, then run $ pipenv graph to inspect the situation.
    Hint: try $ pipenv lock --pre if it is a pre-release dependency.
    Could not find a version that matches pckg3==4.0.11,==4.1.0,&gt;=4.1.0 (from -r C:\Users\user\AppData\Local\Temp\pipenv-o7uxm080-requirements\pipenv-hwekv7dc-constraints.txt (line 2))
    Tried: 3.3.1, 3.3.2, 3.3.3, 3.4.0, 3.4.2, 4.0.0, 4.0.0, 4.0.1, 4.0.1, 4.0.2, 4.0.2, 4.0.3, 4.0.3, 4.0.4, 4.0.4, 4.0.6, 4.0.6, 4.0.8, 4.0.8, 4.0.9, 4.0.9, 4.0.10, 4.0.10, 4.0.11, 4.0.11, 4.1.0, 4.1.0, 4.1.1, 4.1.1, 4.1.2, 4.1.2, 4.2.1, 4.2.1, 4.3.0, 4.3.0
    There are incompatible versions in the resolved dependencies.

As suggested, `pip install --skip-lock` does the trick, but the dependency tree is still unresolved.

I would love to tell `Pipenv` to override `pckg2`&#39;s requirement, and specify `pckg3&gt;=4.1.0`.

How can this be resolved?

How to resolve Python package dependencies with pipenv?

I&#39;m currently trying my hands on the new dataclass constructions introduced in Python 3.7. I am currently stuck on trying to do some inheritance of a parent class. It looks like the order of the arguments are botched by my current approach such that the bool parameter in the child class is passed before the other parameters. This is causing a type error.

    from dataclasses import dataclass
    
    @dataclass
    class Parent:
        name: str
        age: int
        ugly: bool = False
    
        def print_name(self):
            print(self.name)
    
        def print_age(self):
            print(self.age)
    
        def print_id(self):
            print(f&#39;The Name is {self.name} and {self.name} is {self.age} year old&#39;)
    
    @dataclass
    class Child(Parent):
        school: str
        ugly: bool = True
    

    jack = Parent(&#39;jack snr&#39;, 32, ugly=True)
    jack_son = Child(&#39;jack jnr&#39;, 12, school = &#39;havard&#39;, ugly=True)
    
    jack.print_id()
    jack_son.print_id()


When I run this code I get this `TypeError`:

    TypeError: non-default argument &#39;school&#39; follows default argument

How do I fix this?

Class inheritance in Python 3.7 dataclasses

I have a multithreaded function that I would like a status bar for using `tqdm`. Is there an easy way to show a status bar with `ThreadPoolExecutor`? It is the parallelization part that is confusing me.

    import concurrent.futures

    def f(x):
        return f**2
    
    my_iter = range(1000000)
    
    def run(f,my_iter):
        with concurrent.futures.ThreadPoolExecutor() as executor:
            function = list(executor.map(f, my_iter))
        return results
    
    run(f, my_iter) # wrap tqdr around this function?

Use tqdm with concurrent.futures?

The problem originates when I start by cloning a git project that uses pipenv, so it has a Pipfile + Pipfile.lock. I want to use a virtual environment with the project so I run `pipenv shell`. I now have a virtual environment created and I am inside the virtual environment. The project obviously has a lot of dependencies (listed in the Pipfile). I don&#39;t want to have to go through the list in the Pipfile one by one and install them using `pipenv install &lt;package_name&gt;`. Is there a pipenv/pip command that installs all the packages from a Pipfile I already have? Or maybe I need to set up the environment differently than running `pipenv shell`?

How to install dependencies from a copied pipfile inside a virtual environment?

I re-installed windows and opened an existing Pycharm project and get the error &#39;SDK seems invalid&#39; in Settings &gt; Project Interpreter.

The project interpreter path is pointing to python in the venv:

    MyProject\venv\Scripts\python.exe

[![enter image description here][1]][1]


I tried re-adding python.exe:

[![enter image description here][2]][2]

Thats when I get the error:

[![enter image description here][3]][3]

**Update:** here is an error from idea.log, a lot of other issues for virtual environments seem to be with windows environment variables and system paths:

    2018-09-28 19:50:40,275 [  17601]   INFO - hon.packaging.PyPIPackageCache - Loaded 153296 packages from C:\Users\Matt\.PyCharm2018.2\system\python_packages\pypi-cache.json 
    2018-09-28 19:50:40,816 [  18142]   INFO - rains.python.sdk.PythonSdkType - Fatal Python error: Py_Initialize: unable to load the file system codec
    ModuleNotFoundError: No module named &#39;encodings&#39;
    
    Current thread 0x00000fa8 (most recent call first):
    
    Exit code -1073740791 
    2018-09-28 19:50:40,816 [  18142]  ERROR - ns.python.sdk.PythonSdkUpdater - Failed to determine Python&#39;s sys.path value:
    STDOUT: 
    STDERR: Fatal Python error: Py_Initialize: unable to load the file system codec
    ModuleNotFoundError: No module named &#39;encodings&#39;
    
    Current thread 0x00000fa8 (most recent call first):
     
    com.jetbrains.python.sdk.InvalidSdkException: Failed to determine Python&#39;s sys.path value:
    STDOUT: 
    STDERR: Fatal Python error: Py_Initialize: unable to load the file system codec
    ModuleNotFoundError: No module named &#39;encodings&#39;


  [1]: https://i.stack.imgur.com/wFV76.png
  [2]: https://i.stack.imgur.com/amnW0.png
  [3]: https://i.stack.imgur.com/8KiuQ.png

&#39;Cannot setup a Python SDK&#39; in PyCharm project using virtualenv after OS reinstallation

In my project folder I created a *venv* folder:

    python -m venv venv

When I run command `select python interpreter` in Visual Studio Code, my venv folder is not shown. I went one level up like suggested [here][1], but Visual Studio Code doesn&#39;t see my virtual interpreter.

What did I miss?

  [1]: https://github.com/Microsoft/vscode-python/issues/2470





How can I set up a virtual environment for Python in Visual Studio Code?

I&#39;ve recently upgraded from `Ubuntu 18.04` to `19.04` which has `python 3.7`. But I work on many projects using `Python 3.6`. 

Now when I try to create a `virtualenv` with `Python 36` in PyCharm, it raises:

    ModuleNotFoundError: No module named &#39;distutils.core&#39;
[![enter image description here][1]][1]

I can&#39;t figure out what to do. 

I tried to install distutils:

    milano@milano-PC:~$ sudo apt-get install python3-distutils
    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    python3-distutils is already the newest version (3.7.3-1ubuntu1).
    0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

But as you can see I have the newest version.

Do you know what to do?

  [1]: https://i.stack.imgur.com/kKMZC.png

ModuleNotFoundError: No module named &#39;distutils.core&#39;

I&#39;m trying to install opencv-python package via pip inside virtual environment (Python 2.7). Unfortunately, I&#39;m getting an error:

    (venv) $ pip2 install opencv-python
    DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support
    Collecting opencv-python
      Using cached opencv-python-4.3.0.38.tar.gz (88.0 MB)
      Installing build dependencies ... done
      Getting requirements to build wheel ... error
      ERROR: Command errored out with exit status 1:
       command: /home/pc_user/.venvs/venv/bin/python /home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmp7q7z4L
           cwd: /tmp/pip-install-C21PKF/opencv-python
      Complete output (22 lines):
      Traceback (most recent call last):
        File &quot;/home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py&quot;, line 280, in &lt;module&gt;
          main()
        File &quot;/home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py&quot;, line 263, in main
          json_out[&#39;return_val&#39;] = hook(**hook_input[&#39;kwargs&#39;])
        File &quot;/home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py&quot;, line 114, in get_requires_for_build_wheel
          return hook(config_settings)
        File &quot;/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py&quot;, line 146, in get_requires_for_build_wheel
          return self._get_build_requires(config_settings, requirements=[&#39;wheel&#39;])
        File &quot;/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py&quot;, line 127, in _get_build_requires
          self.run_setup()
        File &quot;/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py&quot;, line 243, in run_setup
          self).run_setup(setup_script=setup_script)
        File &quot;/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py&quot;, line 142, in run_setup
          exec(compile(code, __file__, &#39;exec&#39;), locals())
        File &quot;setup.py&quot;, line 448, in &lt;module&gt;
          main()
        File &quot;setup.py&quot;, line 99, in main
          % {&quot;ext&quot;: re.escape(sysconfig.get_config_var(&quot;EXT_SUFFIX&quot;))}
        File &quot;/usr/lib/python2.7/re.py&quot;, line 210, in escape
          s = list(pattern)
      TypeError: &#39;NoneType&#39; object is not iterable
      ----------------------------------------
    ERROR: Command errored out with exit status 1: /home/pc_user/.venvs/venv/bin/python /home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmp7q7z4L Check the logs for full command output.


I&#39;ve tried to create a new environment or installing through `python2 -m pip install` but the effect is the same. What&#39;s the problem?

Content Type	Original Author	Original Content on Stackoverflow
Question	problemofficer - n.f. Monica	View Question on Stackoverflow
Solution 1 - Python	tripleee	View Answer on Stackoverflow
Solution 2 - Python	JR ibkr	View Answer on Stackoverflow

Where do I put my python files in the venv folder?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

A comparison between fastparquet and pyarrow?

Angular 6 / 7 "the result of a dependency is an expression"

Attributions