&gt; Python scripts (files with the extension .py) will be executed by
&gt; **python.exe** by default. This executable opens a terminal, which stays
&gt; open even if the program uses a GUI. If you do not want this to
&gt; happen, use the extension .pyw which will cause the script to be
&gt; executed by **pythonw.exe** by default (both executables are located in
&gt; the top-level of your Python installation directory). This suppresses
&gt; the terminal window on startup.
&gt; 
&gt; You can also make all .py scripts execute with pythonw.exe, setting
&gt; this through the usual facilities, for example (might require
&gt; administrative rights):

https://docs.python.org/2/using/windows.html

So in practice the only difference is that one leaves a console window hanging around and the other doesn&#39;t. The most obvious usage for *.pyw are GUI apps since an app with an independent GUI obviously does not need or want the console window around.

There are some subtle implementation differences between python.exe and pythonw.exe see https://stackoverflow.com/a/30313091/3703989

The PYW file type is primarily associated with Python by Python Software Foundation. PYW files are used in Windows to indicate a script needs to be run using PYTHONW. EXE instead of PYTHON. EXE in order to prevent a DOS console from popping up to display the output.

Its just a file extension that tells python to run the script in the background.

I am new to java 8 and I am trying to get five years before now, here is my code:

    Instant fiveYearsBefore = Instant.now().plus(-5,
						ChronoUnit.YEARS);
But I get the following error:

    java.time.temporal.UnsupportedTemporalTypeException: Unsupported unit: Years

Can anyone help me how to do that?

How to get 5 years before now

In a Obj-C iOS app I can use `#if (TARGET_IPHONE_SIMULATOR)` to write simulator-only code.

In react native I can use:

    if (__DEV__) {
     .. do something special
    }

.. to detect development mode.  

We can use `Platform.OS === &#39;ios&#39;` to detect the platform (Android/iOS).
See here for more info [Platform Docs][1]

But how do we detect if the app is running in the simulator?

The reason I ask is that my app uses the camera to scan barcodes, and this isn&#39;t supported in the iOS Simulator.


  [1]: https://facebook.github.io/react-native/docs/platform-specific-code.html

React Native: How can I detect if my code is running in the Simulator?

I am new to Python programming. Can anybody provide an explanation on what a *.pyw file is and how it works. 

.pyw files in python program

<p>I am new to Python programming. Can anybody provide an explanation on what a *.pyw file is and how it works.</p>


I&#39;d like to generate video using `AWS Lambda` feature.

I&#39;ve followed instructions found [here][1] and [here][2].

And I now have the following process to build my `Lambda` function:

## Step 1 ##

Fire a `Amazon Linux EC2` instance and run this as root on it:

&lt;!-- language: lang-sh --&gt;

    #! /usr/bin/env bash
    
    # Install the SciPy stack on Amazon Linux and prepare it for AWS Lambda
    
    yum -y update
    yum -y groupinstall &quot;Development Tools&quot;
    yum -y install blas --enablerepo=epel
    yum -y install lapack --enablerepo=epel
    yum -y install atlas-sse3-devel --enablerepo=epel
    yum -y install Cython --enablerepo=epel
    yum -y install python27
    yum -y install python27-numpy.x86_64
    yum -y install python27-numpy-f2py.x86_64
    yum -y install python27-scipy.x86_64
    
    /usr/local/bin/pip install --upgrade pip
    mkdir -p /home/ec2-user/stack
    /usr/local/bin/pip install moviepy -t /home/ec2-user/stack
    
    cp -R /usr/lib64/python2.7/dist-packages/numpy /home/ec2-user/stack/numpy
    cp -R /usr/lib64/python2.7/dist-packages/scipy /home/ec2-user/stack/scipy
    
    tar -czvf stack.tgz /home/ec2-user/stack/*

## Step 2 ##

I scp the resulting tarball to my laptop. And then run this script to build a zip archive.

&lt;!-- language: lang-sh --&gt;

    #! /usr/bin/env bash
    
    mkdir tmp
    rm lambda.zip
    tar -xzf stack.tgz -C tmp
    
    zip -9 lambda.zip process_movie.py
    zip -r9 lambda.zip *.ttf
    cd tmp/home/ec2-user/stack/
    zip -r9 ../../../../lambda.zip *

`process_movie.py` script is at the moment only a test to see if the stack is ok:

&lt;!-- language: lang-py --&gt;

    def make_movie(event, context):
        import os
        print(os.listdir(&#39;.&#39;))
        print(os.listdir(&#39;numpy&#39;))
        try:
            import scipy
        except ImportError:
            print(&#39;can not import scipy&#39;)
    
        try:
            import numpy
        except ImportError:
            print(&#39;can not import numpy&#39;)
    
        try:
            import moviepy
        except ImportError:
            print(&#39;can not import moviepy&#39;)

## Step 3 ##

Then I upload the resulting archive to S3 to be the source of my `lambda` function.
When I test the function I get the following `callstack`:

    START RequestId: 36c62b93-b94f-11e5-9da7-83f24fc4b7ca Version: $LATEST
    [&#39;tqdm&#39;, &#39;imageio-1.4.egg-info&#39;, &#39;decorator.pyc&#39;, &#39;process_movie.py&#39;, &#39;decorator-4.0.6.dist-info&#39;, &#39;imageio&#39;, &#39;moviepy&#39;, &#39;tqdm-3.4.0.dist-info&#39;, &#39;scipy&#39;, &#39;numpy&#39;, &#39;OpenSans-Regular.ttf&#39;, &#39;decorator.py&#39;, &#39;moviepy-0.2.2.11.egg-info&#39;]
    [&#39;add_newdocs.pyo&#39;, &#39;numarray&#39;, &#39;__init__.py&#39;, &#39;__config__.pyc&#39;, &#39;_import_tools.py&#39;, &#39;setup.pyo&#39;, &#39;_import_tools.pyc&#39;, &#39;doc&#39;, &#39;setupscons.py&#39;, &#39;__init__.pyc&#39;, &#39;setup.py&#39;, &#39;version.py&#39;, &#39;add_newdocs.py&#39;, &#39;random&#39;, &#39;dual.pyo&#39;, &#39;version.pyo&#39;, &#39;ctypeslib.pyc&#39;, &#39;version.pyc&#39;, &#39;testing&#39;, &#39;dual.pyc&#39;, &#39;polynomial&#39;, &#39;__config__.pyo&#39;, &#39;f2py&#39;, &#39;core&#39;, &#39;linalg&#39;, &#39;distutils&#39;, &#39;matlib.pyo&#39;, &#39;tests&#39;, &#39;matlib.pyc&#39;, &#39;setupscons.pyc&#39;, &#39;setup.pyc&#39;, &#39;ctypeslib.py&#39;, &#39;numpy&#39;, &#39;__config__.py&#39;, &#39;matrixlib&#39;, &#39;dual.py&#39;, &#39;lib&#39;, &#39;ma&#39;, &#39;_import_tools.pyo&#39;, &#39;ctypeslib.pyo&#39;, &#39;add_newdocs.pyc&#39;, &#39;fft&#39;, &#39;matlib.py&#39;, &#39;setupscons.pyo&#39;, &#39;__init__.pyo&#39;, &#39;oldnumeric&#39;, &#39;compat&#39;]
    can not import scipy
    &#39;module&#39; object has no attribute &#39;core&#39;: AttributeError
    Traceback (most recent call last):
      File &quot;/var/task/process_movie.py&quot;, line 91, in make_movie
        import numpy
      File &quot;/var/task/numpy/__init__.py&quot;, line 122, in &lt;module&gt;
        from numpy.__config__ import show as show_config
      File &quot;/var/task/numpy/numpy/__init__.py&quot;, line 137, in &lt;module&gt;
        import add_newdocs
      File &quot;/var/task/numpy/numpy/add_newdocs.py&quot;, line 9, in &lt;module&gt;
        from numpy.lib import add_newdoc
      File &quot;/var/task/numpy/lib/__init__.py&quot;, line 13, in &lt;module&gt;
        from polynomial import *
      File &quot;/var/task/numpy/lib/polynomial.py&quot;, line 11, in &lt;module&gt;
        import numpy.core.numeric as NX
    AttributeError: &#39;module&#39; object has no attribute &#39;core&#39;
    
    END RequestId: 36c62b93-b94f-11e5-9da7-83f24fc4b7ca
    REPORT RequestId: 36c62b93-b94f-11e5-9da7-83f24fc4b7ca	Duration: 112.49 ms	Billed Duration: 200 ms 	Memory Size: 1536 MB	Max Memory Used: 14 MB

	
I cant understand why python does not found the core directory that is present in the folder structure.


EDIT:

Following @jarmod advice I&#39;ve reduced the `lambda`function to:

&lt;!-- language: lang-py --&gt;

    def make_movie(event, context):
        print(&#39;running make movie&#39;)
        import numpy

I now have the following error:

    START RequestId: 6abd7ef6-b9de-11e5-8aee-918ac0a06113 Version: $LATEST
    running make movie
    Error importing numpy: you should not try to import numpy from
            its source directory; please exit the numpy source tree, and relaunch
            your python intepreter from there.: ImportError
    Traceback (most recent call last):
      File &quot;/var/task/process_movie.py&quot;, line 3, in make_movie
        import numpy
      File &quot;/var/task/numpy/__init__.py&quot;, line 127, in &lt;module&gt;
        raise ImportError(msg)
    ImportError: Error importing numpy: you should not try to import numpy from
            its source directory; please exit the numpy source tree, and relaunch
            your python intepreter from there.
    
    END RequestId: 6abd7ef6-b9de-11e5-8aee-918ac0a06113
    REPORT RequestId: 6abd7ef6-b9de-11e5-8aee-918ac0a06113	Duration: 105.95 ms	Billed Duration: 200 ms 	Memory Size: 1536 MB	Max Memory Used: 14 MB

	

  [1]: http://docs.aws.amazon.com/lambda/latest/dg/with-s3-example-deployment-pkg.html#with-s3-example-deployment-pkg-python
  [2]: http://www.perrygeo.com/running-python-with-compiled-code-on-aws-lambda.html

Using moviepy, scipy and numpy in amazon lambda

Let&#39;s say we have a dummy function:

    async def foo(arg):
        result = await some_remote_call(arg)
        return result.upper()

What&#39;s the difference between:

    import asyncio    

    coros = []
    for i in range(5):
        coros.append(foo(i))

    loop = asyncio.get_event_loop()
    loop.run_until_complete(asyncio.wait(coros))

And:

    import asyncio

    futures = []
    for i in range(5):
        futures.append(asyncio.ensure_future(foo(i)))

    loop = asyncio.get_event_loop()
    loop.run_until_complete(asyncio.wait(futures))

*Note*: The example returns a result, but this isn&#39;t the focus of the question. When return value matters, use `gather()` instead of `wait()`.

Regardless of return value, I&#39;m looking for clarity on `ensure_future()`. `wait(coros)` and `wait(futures)` both run the coroutines, so when and why should a coroutine be wrapped in `ensure_future`?

Basically, what&#39;s the Right Way (tm) to run a bunch of non-blocking operations using Python 3.5&#39;s `async`?

For extra credit, what if I want to batch the calls? For example, I need to call `some_remote_call(...)` 1000 times, but I don&#39;t want to crush the web server/database/etc with 1000 simultaneous connections. This is doable with a thread or process pool, but is there a way to do this with `asyncio`?

**2020 update (Python 3.7+)**: Don&#39;t use these snippets. Instead use:

    import asyncio

    async def do_something_async():
        tasks = []
        for i in range(5):
            tasks.append(asyncio.create_task(foo(i)))
        await asyncio.gather(*tasks)

    def do_something():
        asyncio.run(do_something_async)

Also consider using [Trio][1], a robust 3rd party alternative to asyncio.


  [1]: https://trio.readthedocs.io/

Difference between coroutine and future/task in Python 3.5?

What&#39;s the most pythonic way to mesh two strings together?

For example:

Input:

    u = &#39;ABCDEFGHIJKLMNOPQRSTUVWXYZ&#39;
    l = &#39;abcdefghijklmnopqrstuvwxyz&#39;

Output:

    &#39;AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz&#39;


Most pythonic way to interleave two strings

I just upgraded to the latest stable release of `matplotlib` (1.5.1) and everytime I import matplotlib I get this message:

    /usr/local/lib/python2.7/dist-packages/matplotlib/font_manager.py:273: UserWarning: Matplotlib is building the font cache using fc-list. This may take a moment.
      warnings.warn(&#39;Matplotlib is building the font cache using fc-list. This may take a moment.&#39;)

... which always stalls for a few seconds.

Is this the expected behaviour? Was it the same also before, but just without the printed message?

matplotlib taking time when being imported

I&#39;d like to replace bad values in a column of a dataframe by NaN&#39;s.

    mydata = {&#39;x&#39; : [10, 50, 18, 32, 47, 20], &#39;y&#39; : [&#39;12&#39;, &#39;11&#39;, &#39;N/A&#39;, &#39;13&#39;, &#39;15&#39;, &#39;N/A&#39;]}
    df = pd.DataFrame(mydata)

    df[df.y == &#39;N/A&#39;][&#39;y&#39;] = np.nan

Though, the last line fails and throws a warning because it&#39;s working on a copy of df. So, what&#39;s the correct way to handle this? I&#39;ve seen many solutions with iloc or ix but here, I need to use a boolean condition.


How to set a cell to NaN in a pandas dataframe

I&#39;m trying to execute ansible2 commnads...

When I do:

    ansible-playbook -vvv -i my/inventory my/playbook.yml

I get:

&gt; Unexpected Exception: name &#39;basestring&#39; is not defined
the full traceback was:

&gt;     Traceback (most recent call last):
      File &quot;/usr/local/bin/ansible-playbook&quot;, line 85, in &lt;module&gt;
        sys.exit(cli.run())
      File &quot;/usr/local/lib/python3.4/site-packages/ansible/cli/playbook.py&quot;, line 150, in run
        results = pbex.run()
      File &quot;/usr/local/lib/python3.4/site-packages/ansible/executor/playbook_executor.py&quot;, line 87, in run
        self._tqm.load_callbacks()
      File &quot;/usr/local/lib/python3.4/site-packages/ansible/executor/task_queue_manager.py&quot;, line 149, in load_callbacks
        elif isinstance(self._stdout_callback, basestring):
    NameError: name &#39;basestring&#39; is not defined

Here is `ansible --version`:

    ansible 2.0.0.2
      config file = /etc/ansible/ansible.cfg
      configured module search path = Default w/o overrides

And here is `python --version`

    Python 3.4.3

Unexpected Exception: name &#39;basestring&#39; is not defined when invoking ansible2

I have code that expects `str` but will handle the case of being passed `bytes` in the following way:

    if isinstance(data, bytes):
        data = data.decode()

Unfortunately, this does not work in the case of `bytearray`.  Is there a more generic way to test whether an object is either `bytes` or `bytearray`, or should I just check for both?  Is `hasattr(&#39;decode&#39;)` as bad as I feel it would be?

What is the proper way to determine if an object is a bytes-like object in Python?

I am implementing fft as part of my homework. My problem lies in the implemention of shuffling data elements using bit reversal. I get the following warning: 

&gt; DeprecationWarning: using a non-integer number instead of an integer will result in an error in the future.
&gt;
&gt;    data[x], data[y] = data[y], data[x]

And the auto grading system (provided by university) returns the following: 

&gt; error: only integers, slices (`:`), ellipsis (`...`), numpy.newaxis (`None`) and integer or boolean arrays are valid indices.

My code is:

    def shuffle_bit_reversed_order(data: np.ndarray) -&gt; np.ndarray:
        &quot;&quot;&quot;
        Shuffle elements of data using bit reversal of list index.
    
        Arguments:
        data: data to be transformed (shape=(n,), dtype=&#39;float64&#39;)
    
        Return:
        data: shuffled data array
        &quot;&quot;&quot;
    
        # implement shuffling by reversing index bits
    
        size = data.size
    
        half = size/2;
    
        for x in range(size):
            xx = np.int(x)
            n = np.int(half)
    
            y = 0
    
            while n &gt; 0:
                y += n * np.mod(xx,2)
                n /= 2
                xx = np.int(xx /2)
    
            if (y &gt; x):
    
                data[x], data[y] = data[y], data[x]
    
        return data


I have already implemented the function for fft but it won&#39;t work until I get this shuffling function working. I think the problem is my data is of type &#39;float64&#39; and I may have used it as an integer but I don&#39;t know how I can solve it. 



Content Type	Original Author	Original Content on Stackoverflow
Question	Arnb	View Question on Stackoverflow
Solution 1 - Python	absolutelyNoWarranty	View Answer on Stackoverflow
Solution 2 - Python	Manikandan k	View Answer on Stackoverflow
Solution 3 - Python	codeforever10	View Answer on Stackoverflow

.pyw files in python program

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

React Native: How can I detect if my code is running in the Simulator?

How to get 5 years before now

Attributions