[`sys.stdout`][1] is a file object corresponding to the program&#39;s standard output. You can use its `write()` method. Note that it&#39;s probably not necessary to use the `with` statement, because `stdout` does not have to be opened or closed.

So, if you need to create a `csv.writer` object, you can just say:

    import sys
    spamwriter = csv.writer(sys.stdout)

  [1]: https://docs.python.org/3/library/sys.html#sys.stdout
  [2]: https://docs.python.org/3/library/functions.html#print


I recently bought chinesse device that connects via bluetooth with android phone / tablet. Since there is no application availible for windows / linux I want to create one for personal usage.

Usually phone connects to the device and exchanges some data. I connected PC to the device and looked into serial debugger and menaged to discover the protocol (one way only). Phone sends only one command to the device. But this time I&#39;m not able to find out what it containts. 

Is there any software that will allow me to look into data sent via bluetooth? I tried decompiling the app, but it looks really unfriendly.

Thanks.



Sniffing/logging your own Android Bluetooth traffic

I an using python 2.7 and trying to pickle an object. I am wondering what the real difference is between the pickle protocols.

    import numpy as np
    import pickle

    class Data(object):
      def __init__(self):
        self.a = np.zeros((100, 37000, 3), dtype=np.float32)

    d = Data()
    print(&quot;data size: &quot;, d.a.nbytes / 1000000.0)
    print(&quot;highest protocol: &quot;, pickle.HIGHEST_PROTOCOL)
    pickle.dump(d, open(&quot;noProt&quot;, &quot;w&quot;))
    pickle.dump(d, open(&quot;prot0&quot;, &quot;w&quot;), protocol=0)
    pickle.dump(d, open(&quot;prot1&quot;, &quot;w&quot;), protocol=1)
    pickle.dump(d, open(&quot;prot2&quot;, &quot;w&quot;), protocol=2)

    
    out &gt;&gt; data size:  44.4
    out &gt;&gt; highest protocol:  2

then I found that the saved files have different sizes on disk:

* `noProt`: 177.6MB  
* `prot0`: 177.6MB  
* `prot1`: 44.4MB  
* `prot2`: 44.4MB

    
I know that `prot0` is a human readable text file, so I don&#39;t want to use it.
I guess protocol 0 is the one given by default.

I wonder what&#39;s the difference between protocols 1 and 2, is there a reason why I should chose one or another?

What&#39;s is the better to use, `pickle` or `cPickle`?


Python pickle protocol choice?

I know I can write a CSV file with something like:

    with open(&#39;some.csv&#39;, &#39;w&#39;, newline=&#39;&#39;) as f:

How would I instead write that output to `stdout`?

How to write CSV output to stdout?

I know I can write a CSV file with something like:
<pre><code class="hljs language-python">with open('some.csv', 'w', newline='') as f:
</code></pre>
How would I instead write that output to <code>stdout</code>?

The `pandas` `drop_duplicates` function is great for &quot;uniquifying&quot; a dataframe. However, one of the keyword arguments to pass is `take_last=True` or `take_last=False`, while I would like to drop all rows which are duplicates across a subset of columns. Is this possible?

		A	B	C
	0	foo 0	A
	1	foo	1	A
	2	foo	1	B
	3	bar 1	A
	
As an example, I would like to drop rows which match on columns `A` and `C` so this should drop rows 0 and 1.

Drop all duplicate rows across multiple columns in Python Pandas

What is the difference between `setUp()` and `setUpClass()` in the Python `unittest` framework? Why would setup be handled in one method over the other?

I want to understand what part of setup is done in the `setUp()` and `setUpClass()` functions, as well as with `tearDown()` and `tearDownClass()`.

What is the difference between setUp() and setUpClass() in Python unittest?

I have 3 CSV files. Each has the first column as the (string) names of people, while all the other columns in each dataframe are attributes of that person. 

How can I &quot;join&quot; together all three CSV documents to create a single CSV with each row having all the attributes for each unique value of the person&#39;s string name?

The `join()` function in pandas specifies that I need a multiindex, but I&#39;m confused about what a hierarchical indexing scheme has to do with making a join based on a single index. 

pandas three-way joining multiple dataframes on columns

I need to strip a specific word from a string.

But I find python strip method seems can&#39;t recognize an ordered word. The just strip off any characters passed to the parameter.

For example:

    &gt;&gt;&gt; papa = &quot;papa is a good man&quot;
    &gt;&gt;&gt; app = &quot;app is important&quot;
    &gt;&gt;&gt; papa.lstrip(&#39;papa&#39;)
    &quot; is a good man&quot;
    &gt;&gt;&gt; app.lstrip(&#39;papa&#39;)
    &quot; is important&quot;

How could I strip a specified word with python?

How to strip a specific word from a string?

I have a dataframe with a timeindex and 3 columns containing the coordinates of a 3D vector:

                             x             y             z
    ts
    2014-05-15 10:38         0.120117      0.987305      0.116211
    2014-05-15 10:39         0.117188      0.984375      0.122070
    2014-05-15 10:40         0.119141      0.987305      0.119141
    2014-05-15 10:41         0.116211      0.984375      0.120117
    2014-05-15 10:42         0.119141      0.983398      0.118164


I would like to apply a transformation to each row that also returns a vector

    def myfunc(a, b, c):
        do something
        return e, f, g

but if I do:

    df.apply(myfunc, axis=1)

I end up with a Pandas series whose elements are tuples. This is beacause apply will take the result of myfunc without unpacking it. How can I change myfunc so that I obtain a new df with 3 columns?



**Edit:**

All solutions below work. The Series solution does allow for column names, the List solution seem to execute faster.


    def myfunc1(args):
        e=args[0] + 2*args[1]
        f=args[1]*args[2] +1
        g=args[2] + args[0] * args[1]
        return pd.Series([e,f,g], index=[&#39;a&#39;, &#39;b&#39;, &#39;c&#39;])

    def myfunc2(args):
        e=args[0] + 2*args[1]
        f=args[1]*args[2] +1
        g=args[2] + args[0] * args[1]
        return [e,f,g]

    %timeit df.apply(myfunc1 ,axis=1)

    100 loops, best of 3: 4.51 ms per loop

    %timeit df.apply(myfunc2 ,axis=1)

    100 loops, best of 3: 2.75 ms per loop

pandas apply function that returns multiple values to rows in pandas dataframe

I want to configure Sublime Text 3 to build Python 3, but I don&#39;t seem to understand how the builds work. Many tutorials have told me to make a build file containing code such as:

    {
        &#39;cmd&#39;: [&#39;/usr/bin/python3&#39;, &#39;-u&#39;, &#39;$file&#39;],
        &#39;file_regex&#39;: &#39;^[ ]*File &quot;(…*?)&quot;, line ([0-9]*)&#39;,
        &#39;selector&#39;: &#39;source.python&#39;
    }

and save it as a file called `Python.sublime-build` or `python3.sublime-build` (much of the information I found was conflicting). One tutorial suggested creating a new folder in the ST3 Packages folder called `Python` and add the build file in there, whilst other tutorials suggested leaving it in the folder called `User`. 

One tutorial explained how I had to change the Environment Variable `path` on my operating system to get it to work. That didn&#39;t seem to help either.

---

I added a folder `Python` to `Packages` (since it wasn&#39;t there already) and added in a build file with the name `Python.sublime_build` which featured only the code I posted above in it. Now when I attempt to run Sublime Text it gives me this error:

    Error trying to parse build system:
    Expected value in Packages\Python\Python.sublime-build:2:5

Set up Python 3 build system with Sublime Text 3

Using [virtualenv][1], I run my projects with the default version of Python (2.7). On one project, I need to use Python 3.4. 

I used `brew install python3` to install it on my Mac. Now, how do I create a virtualenv that uses the new version?

e.g. sudo virtualenv envPython3

If I try:


    virtualenv -p python3 test

I get:

    Running virtualenv with interpreter /usr/local/bin/python3
    Using base prefix &#39;/usr/local/Cellar/python3/3.4.0_1/Frameworks/Python.framework/Versions/3.4&#39;
    New python executable in test/bin/python3.4
    Also creating executable in test/bin/python
    Failed to import the site module
    Traceback (most recent call last):
      File &quot;/Users/user/Documents/workspace/test/test/bin/../lib/python3.4/site.py&quot;, line 67, in &lt;module&gt;
        import os
      File &quot;/Users/user/Documents/workspace/test/test/bin/../lib/python3.4/os.py&quot;, line 634, in &lt;module&gt;
        from _collections_abc import MutableMapping
    ImportError: No module named &#39;_collections_abc&#39;
    ERROR: The executable test/bin/python3.4 is not functioning
    ERROR: It thinks sys.prefix is &#39;/Users/user/Documents/workspace/test&#39; (should be &#39;/Users/user/Documents/workspace/test/test&#39;)
    ERROR: virtualenv is not compatible with this system or executable

[1]: https://virtualenv.pypa.io/en/latest/

Using Python 3 in virtualenv

If I have a class...

    class MyClass:

        def method(arg):
            print(arg)

...which I use to create an object...

    my_object = MyClass()

...on which I call `method(&quot;foo&quot;)` like so...

    &gt;&gt;&gt; my_object.method(&quot;foo&quot;)
    Traceback (most recent call last):
    File &quot;&lt;stdin&gt;&quot;, line 1, in &lt;module&gt;
    TypeError: method() takes exactly 1 positional argument (2 given)

...why does Python tell me I gave it two arguments, when I only gave one?


TypeError: method() takes 1 positional argument but 2 were given

I&#39;m in Kubuntu 14.04 , I want to create a virtualenv with python3.4. I did with python2.7 before in other folder. But when I try:

    pyvenv-3.4 venv

I&#39;ve got:

`Error: Command &#39;[&#39;/home/fmr/projects/ave/venv/bin/python3.4&#39;, &#39;-Im&#39;, &#39;ensurepip&#39;, &#39;--upgrade&#39;, &#39;--default-pip&#39;]&#39; returned non-zero exit status 1`




pyvenv-3.4 returned non-zero exit status 1

In debugging my code, I want to use a list comprehension. However, it seems I cannot evaluate a list comprehension from the debugger when I&#39;m inside a function.

I am using Python 3.4.

**Script contents**:

    $ cat test.py 
    #!/usr/bin/python
    
    def foo():
        x = [1, 2, 3, 3, 4]
    
        print(x)
    
    foo()

**Interactive debugging:**

    $ python3 -mpdb test.py                                                                                                                                           
    &gt; /tmp/test.py(3)&lt;module&gt;()
    -&gt; def foo():
    (Pdb) step
    &gt; /tmp/test.py(8)&lt;module&gt;()
    -&gt; foo()
    (Pdb) 
    --Call--
    &gt; /tmp/test.py(3)foo()
    -&gt; def foo():
    (Pdb) 
    &gt; /tmp/test.py(4)foo()
    -&gt; x = [1, 2, 3, 3, 4]
    (Pdb) 
    &gt; /tmp/test.py(6)foo()
    -&gt; print(x)
    (Pdb) p [x for _ in range(1)]
    *** NameError: name &#39;x&#39; is not defined
    (Pdb) p x
    [1, 2, 3, 3, 4]

Why is `x` unknown to the list comprehension?  How could I evaluate a list comprehension from the debugger, or achieve an equivalent behaviour?  Is this a bug, or is it some sort of fundamental limitation to the debugger?

List comprehension scope error from Python debugger

Is the output of a Bash command stored in any register? E.g. something similar to `$?` capturing the output instead of the exit status.

I could assign the output to a variable with: 

    output=$(command)

but that&#39;s more typing... 


Reusing output from last command in Bash

A lot of times (not always) the stdout is displayed in colors. Normally I keep every output log in a different file too. Naturally in the file, the colors are not displayed anymore. 

![Console color output example][1]

I&#39;d like to know if there&#39;s a way (in Linux) to write the output to a file with colors. I&#39;m trying to use `tee` to write the output of vagrant to a file, this way I can still see the output (when it applies). I want to use it specifically for vagrant (it may change in the future, of course...) 



  [1]: http://i.stack.imgur.com/ls8Lp.png

How to write stdout to file with colors?

I want to use some useful functions as commands. For that I am testing the `click` library. I defined my three original functions then decorated as `click.command`:

    import click
    import os, sys
    
    @click.command()
    @click.argument(&#39;content&#39;, required=False)
    @click.option(&#39;--to_stdout&#39;, default=True)
    def add_name(content, to_stdout=False):
        if not content:
            content = &#39;&#39;.join(sys.stdin.readlines())
        result = content + &quot;\n\tadded name&quot;
        if to_stdout is True:
            sys.stdout.writelines(result)
        return result
    
    
    @click.command()
    @click.argument(&#39;content&#39;, required=False)
    @click.option(&#39;--to_stdout&#39;, default=True)
    def add_surname(content, to_stdout=False):
        if not content:
            content = &#39;&#39;.join(sys.stdin.readlines())
        result = content + &quot;\n\tadded surname&quot;
        if to_stdout is True:
            sys.stdout.writelines(result)
        return result
    
    @click.command()
    @click.argument(&#39;content&#39;, required=False)
    @click.option(&#39;--to_stdout&#39;, default=False)
    def add_name_and_surname(content, to_stdout=False):
        result = add_surname(add_name(content))
        if to_stdout is True:
            sys.stdout.writelines(result)
        return result

This way I am able to generate the three commands `add_name`, `add_surname` and `add_name_and_surname` using a `setup.py` file and `pip install --editable .` Then I am able to pipe:

    $ echo &quot;original content&quot; | add_name | add_surname 
    original content
    
        added name
        added surname

However there is one slight problem I need to solve, when composing with different click commands as functions:

    $echo &quot;original content&quot; | add_name_and_surname 
    Usage: add_name_and_surname [OPTIONS] [CONTENT]
    
    Error: Got unexpected extra arguments (r i g i n a l   c o n t e n t 
    )

I have no clue why it does not work, I need this `add_name_and_surname` command to call `add_name` and `add_surname` not as command but as functions, else it defeats my original purpose of using functions as both  library functions and commands. 


Call another click command from a click command

(Gradle 3.2.1) I run some java tests, which logs output in Stderr/Stdout. I can see that output, if I start

    gradle test --info

but in that case, much of unwanted output from 3-rd party libraries is there too.

[Documentation][1] suggests using ```logging.caputureStandardError / logging.caputureStandardError (loglevel)```, but it doesn&#39;t seem to have any effect.

    tasks.withType(Test) {
       logging.captureStandardOutput LogLevel.QUIET
       logging.captureStandardError LogLevel.QUIET
    }

Then if running ```gradle test```, not STDERR/STDOUT is output in console.

How can I get just the output from the tests classes in console?


  [1]: https://docs.gradle.org/current/userguide/logging.html#sec:external_tools

Content Type	Original Author	Original Content on Stackoverflow
Question	jsf80238	View Question on Stackoverflow
Solution 1 - Python	Lev Levitsky	View Answer on Stackoverflow

How to write CSV output to stdout?

Python Problem Overview

Python Solutions

Solution 1 - Python

Python pickle protocol choice?

Sniffing/logging your own Android Bluetooth traffic

Attributions