Managed to answer this myself.


`typing.Dict` should be used to indicate a literal `dict` type with support for element type hinting i.e. `Dict[bytes, str]`

`typing.Mapping` is an object which defines the `__getitem__,__len__,__iter__` magic methods

`typing.MutableMapping` is an object which defines same as Mapping but with `__setitem__,__delitem__` magic methods as well.

typing.Mapping et al. are based on the abc types in [this table](https://docs.python.org/3/library/collections.abc.html#collections-abstract-base-classes)

## TL:DR: How can I remove all installed packages from `base`?

I installed a bunch of machine learning packages in my `base` conda environment.

I&#39;ve now created a `ml` environment for machine learning, and wish to reset my `base` environment by removing all the packages installed there.



I&#39;ve tried:

    % activate base
    % conda uninstall -n base --all
    
    CondaEnvironmentError: cannot remove current environment. deactivate and run conda remove again


Apparently, I can&#39;t remove packages from the current environment(?!), so lets switch to my `ml` environment first:

    % source activate ml
    % conda uninstall -n base --all
    
    CondaEnvironmentError: cannot remove root environment,
           add -n NAME or -p PREFIX option

Orright, I&#39;ll use `-p` then...

    % conda uninstall -p ~/.local/share/miniconda3 --all
    
    CondaEnvironmentError: cannot remove root environment,
           add -n NAME or -p PREFIX option


How do I uninstall all installed packages in the `base` or `root` environment?

conda: remove all installed packages from base/root environment

After migrating application from angular 5 to 6, on running ng serve the following errors pop up.

&gt; Schema validation failed with the following errors:
  Data path &quot;&quot; should NOT have additional properties(project).
Error: Schema validation failed with the following errors:
  Data path &quot;&quot; should NOT have additional properties(project).
    at MergeMapSubscriber._registry.compile.pipe.operators_1.concatMap.validatorResult [as project] (.../TemplateApp/me-cmf-web-template-angular/node_modules/@angular-devkit/core/src/workspace/workspace.js:210:42)
    at MergeMapSubscriber._tryNext (/.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/mergeMap.js:65:27)
    at MergeMapSubscriber._next (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/mergeMap.js:55:18)
    at MergeMapSubscriber.Subscriber.next (/home/training/Attinad_Projects/TemplateApp/me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:64:18)
    at MergeMapSubscriber.notifyNext (.../TemplateApp/me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/mergeMap.js:84:26)
    at InnerSubscriber._next (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/InnerSubscriber.js:25:21)
    at InnerSubscriber.Subscriber.next (/.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:64:18)
    at MapSubscriber._next (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/map.js:52:26)
    at MapSubscriber.Subscriber.next (/.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:64:18)
    at SwitchMapSubscriber.notifyNext (.../me-cmf-web-template-angular/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/switchMap.js:77:26)

 

I assume that the error is with .angular.json file which I re-named from .angular-cli.json . 

My .angular.json file is as follows : 



    {
        &quot;$schema&quot;: &quot;./node_modules/@angular/cli/lib/config/schema.json&quot;,
        &quot;project&quot;: {
            &quot;name&quot;: &quot;mediaweb&quot;
        },
        &quot;apps&quot;: [{
                &quot;root&quot;: &quot;src&quot;,
                &quot;outDir&quot;: &quot;dist/browser&quot;,
                &quot;assets&quot;: [
                    &quot;assets&quot;,
                    &quot;favicon.ico&quot;
                ],
                &quot;index&quot;: &quot;index.html&quot;,
                &quot;main&quot;: &quot;main.ts&quot;,
                &quot;polyfills&quot;: &quot;polyfills.ts&quot;,
                &quot;test&quot;: &quot;test.ts&quot;,
                &quot;tsconfig&quot;: &quot;tsconfig.app.json&quot;,
                &quot;testTsconfig&quot;: &quot;tsconfig.spec.json&quot;,
                &quot;prefix&quot;: &quot;app&quot;,
                &quot;styles&quot;: [
                    &quot;styles.scss&quot;,
                    &quot;../node_modules/owl.carousel/dist/assets/owl.carousel.css&quot;,
                    &quot;../node_modules/owl.carousel/dist/assets/owl.theme.default.css&quot;,
                    &quot;../node_modules/video.js/dist/video-js.css&quot;
                ],
                &quot;scripts&quot;: [
                    &quot;../node_modules/jquery/dist/jquery.js&quot;,
                    &quot;../node_modules/owl.carousel/dist/owl.carousel.js&quot;,
                    &quot;../node_modules/video.js/dist/ie8/videojs-ie8.js&quot;,
                    &quot;../node_modules/video.js/dist/video.js&quot;
                ],
                &quot;environmentSource&quot;: &quot;environments/environment.ts&quot;,
                &quot;environments&quot;: {
                    &quot;dev&quot;: &quot;environments/environment.dev.ts&quot;,
                    &quot;prod&quot;: &quot;environments/environment.prod.ts&quot;
                }
            },
            {
                &quot;platform&quot;: &quot;server&quot;,
                &quot;root&quot;: &quot;src&quot;,
                &quot;outDir&quot;: &quot;dist/server&quot;,
                &quot;assets&quot;: [
                    &quot;assets&quot;,
                    &quot;favicon.ico&quot;
                ],
                &quot;index&quot;: &quot;index.html&quot;,
                &quot;main&quot;: &quot;main.server.ts&quot;,
                &quot;test&quot;: &quot;test.ts&quot;,
                &quot;tsconfig&quot;: &quot;tsconfig.server.json&quot;,
                &quot;testTsconfig&quot;: &quot;tsconfig.spec.json&quot;,
                &quot;prefix&quot;: &quot;app&quot;,
                &quot;styles&quot;: [
                    &quot;styles.scss&quot;
                ],
                &quot;scripts&quot;: [],
                &quot;environmentSource&quot;: &quot;environments/environment.ts&quot;,
                &quot;environments&quot;: {
                    &quot;dev&quot;: &quot;environments/environment.dev.ts&quot;,
                    &quot;prod&quot;: &quot;environments/environment.prod.ts&quot;
                }
            }
        ],
        &quot;e2e&quot;: {
            &quot;protractor&quot;: {
                &quot;config&quot;: &quot;./protractor.conf.js&quot;
            }
        },
        &quot;lint&quot;: [{
                &quot;project&quot;: &quot;src/tsconfig.app.json&quot;,
                &quot;exclude&quot;: [&quot;**/node_modules/**&quot;, &quot;**/UI/**&quot;]
            },
            {
                &quot;project&quot;: &quot;src/tsconfig.spec.json&quot;,
                &quot;exclude&quot;: &quot;**/node_modules/**&quot;
            },
            {
                &quot;project&quot;: &quot;e2e/tsconfig.e2e.json&quot;,
                &quot;exclude&quot;: &quot;**/node_modules/**&quot;
            }
        ],
        &quot;test&quot;: {
            &quot;karma&quot;: {
                &quot;config&quot;: &quot;./karma.conf.js&quot;
            }
        },
        &quot;defaults&quot;: {
            &quot;styleExt&quot;: &quot;scss&quot;,
            &quot;component&quot;: {}
        }
    }

Should I re-structure the json file, if so how?.

Any help would be great.




Error: Schema validation failed with the following errors: Data path &quot;&quot; should NOT have additional properties(project)

I&#39;m working on a python3 project where we use the `typing` module type hints throughout.


It seems that we use `typing.Dict` and `typing.Mapping` pretty much interchangeably.

Is there a reason to prefer one over the other?

Python type hints: typing.Mapping vs. typing.Dict

I'm working on a python3 project where we use the <code>typing</code> module type hints throughout.
It seems that we use <code>typing.Dict</code> and <code>typing.Mapping</code> pretty much interchangeably.
Is there a reason to prefer one over the other?

There&#39;s a function which takes optional arguments.

    def alpha(p1=&quot;foo&quot;, p2=&quot;bar&quot;):
         print(&#39;{0},{1}&#39;.format(p1, p2))

Let me iterate over what happens when we use that function in different ways:

    &gt;&gt;&gt; alpha()
    foo,bar
    &gt;&gt;&gt; alpha(&quot;FOO&quot;)
    FOO,bar
    &gt;&gt;&gt; alpha(p2=&quot;BAR&quot;)
    foo,BAR
    &gt;&gt;&gt; alpha(p1=&quot;FOO&quot;, p2=None)
    FOO,None
Now consider the case where I want to call it like `alpha(&quot;FOO&quot;, myp2)` and `myp2` will either contain a value to be passed, or be `None`. But even though the function handles `p2=None`, I want it to use its default value `&quot;bar&quot;` instead.  
Maybe that&#39;s worded confusingly, so let me reword that:  

&gt; If `myp2 is None`, call `alpha(&quot;FOO&quot;)`.   Else, call `alpha(&quot;FOO&quot;, myp2)`.

The distinction is relevant because `alpha(&quot;FOO&quot;, None)` has a different result than `alpha(&quot;FOO&quot;)`.  

**How can I concisely (but readably) make this distinction?**  

One possibility would usually be to [check for None within `alpha`](https://stackoverflow.com/questions/16576553/python-only-pass-arguments-if-the-variable-exists), which would be encouraged because that would make the code safer. But assume that `alpha` is used in other places where it is actually supposed to handle `None` as it does.  

**I&#39;d like to handle that on the caller-side**.  

One possibility is to do a case distinction:

    if myp2 is None:
        alpha(&quot;FOO&quot;)
    else:
        alpha(&quot;FOO&quot;, myp2)
But that can quickly become much code when there are multiple such arguments. (exponentially, 2^n)

Another possibility is to simply do `alpha(&quot;FOO&quot;, myp2 or &quot;bar&quot;)`, but _that requires us to know the default value_. Usually, I&#39;d probably go with this approach, but I might later change the default values for `alpha` and this call would then need to be updated manually in order to still call it with the (new) default value.

I am using python 3.4 but it would be best if your answers can provide a good way that works in any python version.


----------
The question is technically finished here, but I reword some requirement again, since the first answer did gloss over that:  
I want the behaviour of `alpha` with its default values `&quot;foo&quot;, &quot;bar&quot;` preserved in general, so it is (probably) not an option to change `alpha` itself.  
In yet again other words, assume that `alpha` is being used somewhere else as `alpha(&quot;FOO&quot;, None)` where the output `FOO,None` is expected behaviour.

Call function without optional arguments if they are None

Server: Raspberry Pi 3  
OS: Dietpi - version 159  
Geckodriver version: 0.22 for arm  
Firefox version: 52.9.0  
Python version: 3.5  
Selenium version: 3.14.1  

Gecko is executable, and is located in /usr/local/bin/

    from selenium import webdriver
    from selenium.webdriver.common.by import By
    from selenium.webdriver.support.ui import WebDriverWait
    from selenium.webdriver.support import expected_conditions as EC
    from selenium.webdriver.firefox.options import Options
    import time
    
    
    
    options = Options()
    options.set_headless(headless=True)
    driver = webdriver.Firefox(firefox_options=options)
    
    print(&#39;Need your login credential&#39;)
    username = input(&#39;What is your username?:\n&#39;)
    password = input(&#39;What is your password?:\n&#39;)
    ...
    ...

Output:

    root@RPi3:~# python3.5 ITE-bot.py 
    Traceback (most recent call last):
      File &quot;ITE-bot.py&quot;, line 12, in &lt;module&gt;
        driver = webdriver.Firefox(firefox_options=options)
      File &quot;/usr/local/lib/python3.5/dist-packages/selenium/webdriver/firefox/webdriver.py&quot;, line 174, in __init__
        keep_alive=True)
      File &quot;/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/webdriver.py&quot;, line 157, in __init__
        self.start_session(capabilities, browser_profile)
      File &quot;/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/webdriver.py&quot;, line 252, in start_session
        response = self.execute(Command.NEW_SESSION, parameters)
      File &quot;/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/webdriver.py&quot;, line 321, in execute
        self.error_handler.check_response(response)
      File &quot;/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/errorhandler.py&quot;, line 242, in check_response
        raise exception_class(message, screen, stacktrace)
    selenium.common.exceptions.WebDriverException: Message: invalid argument: can&#39;t kill an exited process

Any idea what is wrong? I&#39;ve tried google without luck.

WebDriverException: Message: invalid argument: can&#39;t kill an exited process with GeckoDriver, Selenium and Python on RaspberryPi3

I want Pipenv to make virtual environment in the same folder with my project (Django).

I searched and found the `PIPENV_VENV_IN_PROJECT` option but I don&#39;t know where and how to use this.

Make Pipenv create the virtualenv in the same folder

I have a dataframe ```df``` as follows:

    | name  | coverage |
    |-------|----------|
    | Jason | 25.1     |
I want to convert it to a dictionary.
I used the following command in ```pandas``` :

    dict=df.to_dict()
The output of ```dict``` gave me the following:

    {&#39;coverage&#39;: {0: 25.1}, &#39;name&#39;: {0: &#39;Jason&#39;}} 
I do not want the ```0``` in my output. I believe this is captured because of the column index in my dataframe ```df```.
What can I do to eliminate ```0``` in my output
( I do not want index to be captured.) expected output :

    {&#39;coverage&#39;: 25.1, &#39;name&#39;: &#39;Jason&#39;} 



How to convert dataframe to dictionary in pandas WITHOUT index

I&#39;m confused about how to use `asyncio.Queue` for a particular producer-consumer pattern in which both the producer and consumer operate concurrently and independently.

First, consider this example, which closely follows that from the [docs for `asyncio.Queue`](https://docs.python.org/3/library/asyncio-queue.html#examples):

    import asyncio
    import random
    import time

    async def worker(name, queue):
        while True:
            sleep_for = await queue.get()
            await asyncio.sleep(sleep_for)
            queue.task_done()
            print(f&#39;{name} has slept for {sleep_for:0.2f} seconds&#39;)

    async def main(n):
        queue = asyncio.Queue()
        total_sleep_time = 0
        for _ in range(20):
            sleep_for = random.uniform(0.05, 1.0)
            total_sleep_time += sleep_for
            queue.put_nowait(sleep_for)
        tasks = []
        for i in range(n):
            task = asyncio.create_task(worker(f&#39;worker-{i}&#39;, queue))
            tasks.append(task)
        started_at = time.monotonic()
        await queue.join()
        total_slept_for = time.monotonic() - started_at
        for task in tasks:
            task.cancel()
        # Wait until all worker tasks are cancelled.
        await asyncio.gather(*tasks, return_exceptions=True)
        print(&#39;====&#39;)
        print(f&#39;3 workers slept in parallel for {total_slept_for:.2f} seconds&#39;)
        print(f&#39;total expected sleep time: {total_sleep_time:.2f} seconds&#39;)

    if __name__ == &#39;__main__&#39;:
        import sys
        n = 3 if len(sys.argv) == 1 else sys.argv[1]
        asyncio.run(main())

There is one finer detail about this script: the items are put into the queue synchronously, with `queue.put_nowait(sleep_for)` over a conventional for-loop.

My goal is to create a script that uses `async def worker()` (or `consumer()`) and `async def producer()`.  Both should be scheduled to run concurrently.  No one consumer coroutine is explicitly tied to or chained from a producer.

How can I modify the program above so that the producer(s) is its own coroutine that can be scheduled concurrently with the consumers/workers?

----

&lt;sub&gt;There is a second example from [PYMOTW](https://pymotw.com/3/asyncio/synchronization.html#queues).  It requires the producer to know the number of consumers ahead of time, and uses `None` as a signal to the consumer that production is done.&lt;/sub&gt;


Using asyncio.Queue for producer-consumer flow

I&#39;m trying to install tensorflow but it needs a Python 3.6 installation and I only have Python 3.7 installed. I tried to switch using brew and pyenv but it doesn&#39;t work. 

Does anyone know of a way to solve this problem?

How to downgrade python from 3.7 to 3.6

I have this piece of code:

    
    import enum
    
    
    class Color(enum.Enum):
        RED = &#39;1&#39;
        BLUE = &#39;2&#39;
        GREEN = &#39;3&#39;
    
    
    def get_color_return_something(some_color):
        pass
    
How do I properly add type annotations to the `some_color` variable in this function, if I suppose that I&#39;ll receive an enum attribute from the Color enum (for example: `Color.RED`)?

Type annotations for Enum attribute

I have below try-except to catch JSON parse errors:

    with open(json_file) as j:
        try:
            json_config = json.load(j)
        except ValueError as e:
            raise Exception(&#39;Invalid json: {}&#39;.format(e))

Why is `During handling of the above exception, another exception occurred` printed out, and how do I resolve it?

    json.decoder.JSONDecodeError: Expecting &#39;,&#39; delimiter: line 103 column 9 (char 1093)

    During handling of the above exception, another exception occurred:

    Traceback (most recent call last):
    &lt;....&gt;
    raise Exception(&#39;Invalid json: {}&#39;.format(e))
    Exception: Invalid json: Expecting &#39;,&#39; delimiter: line 103 column 9 (char 1093)

During handling of the above exception, another exception occurred

I have a function that takes a tuple of different lengths as an argument:

```
from typing import Tuple


def process_tuple(t: Tuple[str]):
    # Do nasty tuple stuff

process_tuple((&quot;a&quot;,))
process_tuple((&quot;a&quot;, &quot;b&quot;))
process_tuple((&quot;a&quot;, &quot;b&quot;, &quot;c&quot;))

```

When I annotate function like mentioned above, I get these error messages

```
fool.py:9: error: Argument 1 to &quot;process_tuple&quot; has incompatible type &quot;Tuple[str, str]&quot;; expected &quot;Tuple[str]&quot;
fool.py:10: error: Argument 1 to &quot;process_tuple&quot; has incompatible type &quot;Tuple[str, str, str]&quot;; expected &quot;Tuple[str]&quot;
```

`process_tuple` really works with tuples and I use them as immutable lists of variable length. I haven&#39;t found any consensus on this topic on the internet, so I wonder how should I annotate this kind of input. 

How to annotate function that takes a tuple of variable length? (variadic tuple type annotation)

[`TypeVar`](https://docs.python.org/3/library/typing.html#typing.TypeVar) and [`NewType`](https://docs.python.org/3/library/typing.html#newtype) seem related but I&#39;m not sure when I&#39;m supposed to use each or what the difference is at runtime and statically.

What is the difference between TypeVar and NewType?

I have updated my class definitions to make use of the newly introduced property type hints, like this:

```php
class Foo {
    
    private int $id;
    private ?string $val;
    private DateTimeInterface $createdAt;
    private ?DateTimeInterface $updatedAt;
    
    public function __construct(int $id) {
        $this-&gt;id = $id;
    }


    public function getId(): int { return $this-&gt;id; }
    public function getVal(): ?string { return $this-&gt;val; }
    public function getCreatedAt(): ?DateTimeInterface { return $this-&gt;createdAt; }
    public function getUpdatedAt(): ?DateTimeInterface { return $this-&gt;updatedAt; }
    
    public function setVal(?string $val) { $this-&gt;val = $val; }
    public function setCreatedAt(DateTimeInterface $date) { $this-&gt;createdAt = $date; }
    public function setUpdatedAt(DateTimeInterface $date) { $this-&gt;updatedAt = $date; }
}
```

But when trying to save my entity on Doctrine I am getting an error saying:

&gt; Typed property must not be accessed before initialization 

This not only happens with `$id` or `$createdAt`, but also happen with `$value` or `$updatedAt`, which are nullable properties.

Content Type	Original Author	Original Content on Stackoverflow
Question	stacksonstacks	View Question on Stackoverflow
Solution 1 - Python	stacksonstacks	View Answer on Stackoverflow

Python type hints: typing.Mapping vs. typing.Dict

Python Problem Overview

Python Solutions

Solution 1 - Python

Error: Schema validation failed with the following errors: Data path "" should NOT have additional properties(project)

conda: remove all installed packages from base/root environment

Attributions