You can do this using the splat operator:

    some_func(*params)

This causes the function to receive each list item as a separate parameter. There&#39;s a description here: http://docs.python.org/tutorial/controlflow.html#unpacking-argument-lists

This has already been answered perfectly, but since I just came to this page and did not understand immediately I am just going to add a simple but complete example.

    def some_func(a_char, a_float, a_something):
        print a_char

    params = [&#39;a&#39;, 3.4, None]
    some_func(*params)

    &gt;&gt; a




Use an asterisk:

    some_func(*params)

You want the &lt;a href=&quot;http://docs.python.org/tutorial/controlflow.html#unpacking-argument-lists&quot;&gt;argument unpacking&lt;/a&gt; operator *.

I have a string:

    var names = &quot;Brian,Joe,Chris&quot;;

Is there a way to convert this to a `List&lt;string&gt;` delimited by `,` in one line?

Convert string to List&lt;string&gt; in one line?

Is there a good way to avoid the &quot;host is not resolved&quot; error that crashes an app? Some sort of a way to try connecting to a host ( like a URL ) and see if it&#39;s even valid?

How to check if URL is valid in Android

How can I use a Python list (e.g. &lt;code&gt;params = [&#39;a&#39;,3.4,None]&lt;/code&gt;) as parameters to a function, e.g.:

    def some_func(a_char,a_float,a_something):
       # do stuff

Python - use list as function parameters

How can I use a Python list (e.g. <code>params = ['a',3.4,None]</code>) as parameters to a function, e.g.:
<pre><code class="hljs language-python">def some_func(a_char,a_float,a_something):
 # do stuff
</code></pre>

I&#39;m a bit confused as to how cookies work with Scrapy, and how you manage those cookies.

This is basically a simplified version of what I&#39;m trying to do:
![enter image description here][1]


----------


The way the website works:
--------------------------

When you visit the website you get a session cookie.

When you make a search, the website remembers what you searched for, so when you do something like going to the next page of results, it knows the search it is dealing with.


----------


My script:
----------

My spider has a start url of searchpage_url

The searchpage is requested by `parse()` and the search form response gets passed to `search_generator()`

`search_generator()` then `yield`s lots of search requests using `FormRequest` and the search form response.

Each of those FormRequests, and subsequent child requests need to have it&#39;s own session, so needs to have it&#39;s own individual cookiejar and it&#39;s own session cookie.


----------


I&#39;ve seen the section of the docs that talks about a meta option that stops cookies from being merged. What does that actually mean? Does it mean the spider that makes the request will have its own cookiejar for the rest of its life?

If the cookies are then on a per Spider level, then how does it work when multiple spiders are spawned? Is it possible to make only the first request generator spawn new spiders and make sure that from then on only that spider deals with future requests?

I assume I have to disable multiple concurrent requests.. otherwise one spider would be making multiple searches under the same session cookie, and future requests will only relate to the most recent search made?

I&#39;m confused, any clarification would be greatly received!


----------


EDIT:
-----

Another options I&#39;ve just thought of is managing the session cookie completely manually, and passing it from one request to the other.

I suppose that would mean disabling cookies.. and then grabbing the session cookie from the search response, and passing it along to each subsequent request.

Is this what you should do in this situation?

  [1]: http://i.stack.imgur.com/nn517.png

Scrapy - how to manage cookies/sessions

How can I remove a line (or lines) of a matplotlib axes in such a way as it actually gets garbage collected and releases the memory back?  The below code appears to delete the line, but never releases the memory (even with explicit calls to `gc.collect()`)

    from matplotlib import pyplot
    import numpy
    a = numpy.arange(int(1e7))
    # large so you can easily see the memory footprint on the system monitor.
    fig = pyplot.Figure()
    ax  = pyplot.add_subplot(1, 1, 1)
    lines = ax.plot(a) # this uses up an additional 230 Mb of memory.
    # can I get the memory back?
    l = lines[0]
    l.remove()
    del l
    del lines
    # not releasing memory
    ax.cla() # this does release the memory, but also wipes out all other lines.

So is there a way to just delete one line from an axes and get the memory back?
[This potential solution](https://stackoverflow.com/questions/2732578/delete-lines-in-matplotlib) also does not work.

How to remove lines in a Matplotlib plot

I&#39;m trying to open a webpage using `urllib.request.urlopen()` then search it with regular expressions, but that gives the following error:

&gt; TypeError: can&#39;t use a string pattern on a bytes-like object

I understand why, `urllib.request.urlopen()` returns a bytestream, so `re` doesn&#39;t know the encoding to use. What am I supposed to do in this situation? Is there a way to specify the encoding method in a urlrequest maybe or will I need to re-encode the string myself? If so what am I looking to do, I assume I should read the encoding from the header info or the encoding type if specified in the html and then re-encode it to that?

How to handle response encoding from urllib.request.urlopen() , to avoid TypeError: can&#39;t use a string pattern on a bytes-like object

What would be an **efficient and pythonic** way to check list monotonicity?&lt;br&gt; i.e. that it has monotonically increasing or decreasing values?

Examples:

    [0, 1, 2, 3, 3, 4]   # This is a monotonically increasing list
    [4.3, 4.2, 4.2, -2]  # This is a monotonically decreasing list
    [2, 3, 1]            # This is neither



Python - How to check list monotonicity

I find it more convenient to access dict keys as `obj.foo` instead of `obj[&#39;foo&#39;]`, so I wrote this snippet:

    class AttributeDict(dict):
        def __getattr__(self, attr):
            return self[attr]
        def __setattr__(self, attr, value):
            self[attr] = value

However, I assume that there must be some reason that Python doesn&#39;t provide this functionality out of the box. What would be the caveats and pitfalls of accessing dict keys in this manner?

Accessing dict keys like an attribute?

How do I convert a list to a string in C#?

When I execute `toString` on a List object, I get:

&gt; System.Collections.Generic.List`1[System.String]


Convert a list to a string in C#

I have a `List&lt;MyClass&gt; someList`.

    class MyClass
    {
        public int Prop1...
        public int Prop2...
        public int Prop3...
    }


I would like to know how to get a new distinct `List&lt;MyClass&gt; distinctList` from `List&lt;MyClass&gt; someList`, but only comparing it to `Prop2`.





How to get a distinct list from a List of objects?

I have a list of strings and I have a function to generate a value for each key in the list.

I want to create a map using this function. Can I do this with Google collections?


How to transform List&lt;String&gt; to Map&lt;String,String&gt; with Google collections?

What is the right way to define a function that receives a `int-&gt;int` lambda parameter by reference?

    void f(std::function&lt; int(int) &gt;&amp; lambda);

or 

    void f(auto&amp; lambda);

I&#39;m not sure the last form is even legal syntax.


**Are there other ways to define a lambda parameter?**



c++0x: proper way to receive a lambda as parameter by reference

Could you please point me to the nice way of skipping optional parameters in JavaScript.

For example, I want to throw away all `opt_` parameters here:

    goog.net.XhrIo.send(url, opt_callback, opt_method, opt_content, {&#39;Cache-Control&#39;: &#39;no-cache&#39;}, opt_timeoutInterval)

Skipping optional function parameters in JavaScript

I&#39;ve just come across someone&#39;s C code that I&#39;m confused as to why it is compiling. There are two points I don&#39;t understand.

1.  The **function prototype** has no parameters compared to the actual function definition. 


2. The parameter in the **function definition** does not have a type.


----------


    #include &lt;stdio.h&gt;

    int func();

    int func(param)
    {
    	return param;
    }

    int main()
    {
    	int bla = func(10);    
    	printf(&quot;%d&quot;, bla);
    }



Why does this work? 
I have tested it in a couple of compilers, and it works fine.


Why does a function with no parameters (compared to the actual function definition) compile?

In the following function definition, what do the __*__ and __/__ account for?

    def func(self, param1, param2, /, param3, *, param4, param5):
         print(param1, param2, param3, param4, param5)

*NOTE: Not to mistake with the single|double asterisks in \*args | \*\*kwargs ([solved here][1])*


  [1]: https://stackoverflow.com/questions/36901/what-does-double-star-asterisk-and-star-asterisk-do-for-parameters

Content Type	Original Author	Original Content on Stackoverflow
Question	Jonathan Livni	View Question on Stackoverflow
Solution 1 - Python	Neil Vass	View Answer on Stackoverflow
Solution 2 - Python	Michael David Watson	View Answer on Stackoverflow
Solution 3 - Python	Mark Byers	View Answer on Stackoverflow
Solution 4 - Python	btilly	View Answer on Stackoverflow

Python - use list as function parameters

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

Solution 4 - Python

How to check if URL is valid in Android

Convert string to List<string> in one line?

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