    import itertools
    ab = itertools.chain([&#39;it&#39;], [&#39;was&#39;], [&#39;annoying&#39;])
    list(ab)

Just another method....

Just add them:

    [&#39;it&#39;] + [&#39;was&#39;] + [&#39;annoying&#39;]

You should read [the Python tutorial](http://docs.python.org/tutorial/) to learn basic info like this.


    a = [&#39;it&#39;]
    b = [&#39;was&#39;]
    c = [&#39;annoying&#39;]
    
    a.extend(b)
    a.extend(c)

    # a now equals [&#39;it&#39;, &#39;was&#39;, &#39;annoying&#39;]

I have numbers saved as `VARCHAR` to a MySQL database. I can not make them `INT` due to some other depending circumstances. 

It is taking them as character not as number while sorting.

In database I have 

    1 2 3 4 5 6 7 8 9 10...

On my page it shows ordered list like this:

    1 10 2 3 4 5 6 7 8 9

How can I make it appear ordered by numbers ascending?

SQL order string as number

Given any arbitrary image, I want to crop a square from the center of the image and display it within a given square.

This question is similar to this: https://stackoverflow.com/questions/493296/css-display-an-image-resized-and-cropped, but I don&#39;t know the size of the image so I can&#39;t use set margins. 

How to automatically crop and center an image

&gt; **Possible Duplicate:**  
&gt; [Making a flat list out of list of lists in Python](https://stackoverflow.com/questions/952914/making-a-flat-list-out-of-list-of-lists-in-python)  
&gt; [Join a list of lists together into one list in Python](https://stackoverflow.com/questions/3046217/join-a-list-of-lists-together-into-one-list-in-python)  

&lt;!-- End of automatically inserted text --&gt;

I have many lists which looks like 

    [&#39;it&#39;]
    [&#39;was&#39;]
    [&#39;annoying&#39;]

I want the above to look like 

    [&#39;it&#39;, &#39;was&#39;, &#39;annoying&#39;]

How do I achieve that?

How to merge multiple lists into one list in python?

> Possible Duplicate: 
> <a href="https://stackoverflow.com/questions/952914/making-a-flat-list-out-of-list-of-lists-in-python" target="_blank" rel="noopener noreferrer">Making a flat list out of list of lists in Python</a> 
> <a href="https://stackoverflow.com/questions/3046217/join-a-list-of-lists-together-into-one-list-in-python" target="_blank" rel="noopener noreferrer">Join a list of lists together into one list in Python</a>

I have many lists which looks like
<pre><code class="hljs language-css">['it']
['was']
['annoying']
</code></pre>
I want the above to look like
<pre><code class="hljs language-css">['it', 'was', 'annoying']
</code></pre>
How do I achieve that?

I keep important settings like the hostnames and ports of development and production servers in my version control system. But I know that it&#39;s _bad practice_ to keep *secrets* (like private keys and database passwords) in a VCS repository.

But passwords--like any other setting--seem like they should be versioned. So what *is* the proper way to keep passwords version controlled?

I imagine it would involve keeping the *secrets* in their own &quot;secrets settings&quot; file and having *that* file encrypted and version controlled. But what technologies? And how to do this properly? Is there a better way entirely to go about it?

----------
I ask the question generally, but in my specific instance I would like to store secret keys and passwords for a *Django/Python* site using *git* and *github*.

Also, an *ideal* solution would do something magical when I push/pull with git--e.g., if the encrypted passwords file changes a script is run which asks for a password and decrypts it into place.

&lt;hr&gt;
EDIT: For clarity, I *am* asking about where to store *production* secrets.


How can I save my secret keys and password securely in my version control system?

The python documentation frequently speaks of &quot;containers&quot;. [E.g.][1] :

&gt; If check_circular is False (default: True), then the circular
&gt; reference check for **container types** will be skipped and a circular
&gt; reference will result in an OverflowError (or worse).

But I can&#39;t find any official definition of containers, neither a list of them.

Edit
----
For Python 2.7.3:

**Checked builtin types which are containers:**

(`isinstance(object, collections.Container)` returns `True`)

 1. Containers which have a `__contains__` method defined:
    - All builtin sequence types: Lists, bytearrays, strings, unicode strings and 
tuples.
    - Dictionaries
    - All builtin set types: sets and frozensets


 2. Containers which do not have a `__contains__` method defined:

- xrange objects

**Checked builtin types which are not containers:** 

(`isinstance(object, collections.Container)` returns `False`):

- Int objects
- Float objects
- Long objects
- Boolean objects
- Module objects
- File objects
- Buffer objects
- The None object

Tell me which other builtin types you have checked for `isinstance(object, collections.Container)`  and I&#39;ll add them to the list.


  [1]: http://docs.python.org/library/json.html?highlight=container#basic-usage

What exactly are &quot;containers&quot; in python? (And what are all the python container types?)

I created this plot using Matlab

![enter image description here][1]

Using matplotlib, the x-axies draws large numbers such as 100000, 200000, 300000. I would like to have something like  1, 2, 3 and a 10^5 to indicate that it&#39;s actually 100000, 200000, 300000.

Is there a simple way to create such scale in matplotlib?


  [1]: http://i.stack.imgur.com/8CD22.png

Change x axes scale in matplotlib

After reading the [documentation on `logging`](http://docs.python.org/py3k/library/logging.html#module-logging), I know I can use code like this to perform simple logging:

    import logging
        
    def main():
        logging.basicConfig(filename=&quot;messages.log&quot;,
                            level=logging.WARNING,
                            format=&#39;%(filename)s: &#39;    
                                    &#39;%(levelname)s: &#39;
                                    &#39;%(funcName)s(): &#39;
                                    &#39;%(lineno)d:\t&#39;
                                    &#39;%(message)s&#39;)
    
        logging.debug(&quot;Only for debug purposes\n&quot;)
        logging.shutdown()
    
    main()

However, I realised I don&#39;t know how to change the format of log messages on a per-logger basis, since `basicConfig` is a module-level function. This code works for creating different loggers with different levels, names, etc. but is there a way to change the format of those log messages on a per-logger basis as well, in a way similar to `basicConfig`?

    import inspect
    import logging
    
    def function_logger(level=logging.DEBUG):
        function_name = inspect.stack()[1][3]
        logger = logging.getLogger(function_name)
        logger.setLevel(level)
        logger.addHandler(logging.FileHandler(&quot;{0}.log&quot;.format(function_name)))
        return logger
    
    def f1():
        f1_logger = function_logger()
        f1_logger.debug(&quot;f1 Debug message&quot;)
        f1_logger.warning(&quot;f1 Warning message&quot;)
        f1_logger.critical(&quot;f1 Critical message&quot;)
    
    def f2():
        f2_logger = function_logger(logging.WARNING)
        f2_logger.debug(&quot;f2 Debug message&quot;)
        f2_logger.warning(&quot;f2 Warning message&quot;)
        f2_logger.critical(&quot;f2 Critical message&quot;)
    
    def main():
        f1()
        f2()
        logging.shutdown()
    
    main()




How do I change the format of a Python log message on a per-logger basis?

I&#39;m trying to get the python postgres client module installed on Ubuntu 12.04.  The guidance is to do the following:

    apt-get install python-psycopg2

However, `apt` says that the package can&#39;t be located.  
I&#39;m keen to install this through `apt`.  Is this part of another package that I can install?


Install psycopg2 on Ubuntu

This may seem an odd thing to want to do but ignoring that, is there a nice concise way of converting a `List&lt;string&gt;` to `Dictionary&lt;string, string&gt;` where each Key Value Pair in the Dictionary is just each string in the List. i.e.

    List = string1, string2, string3
    Dictionary = string1/string1, string2/string2, string3/string3

I have done plenty of searching and there are literally dozens of examples on Stackoverflow alone of doing it in the opposite direction but not this way round.

The reason for doing this is I have two third part components and changing them is out of my hands. One returns a list of email addresses as a `List&lt;string&gt;` and the other send emails where the To parameter is a `Dictionary&lt;string, string&gt;`. The key of the dictionary is the email address and the value is their real name. However, I don&#39;t know the real name but it still works if you set the real name to the email address as well. Therefore why I want to convert a List&lt;string&gt; to a `Dictionary&lt;string, string&gt;`. There are plenty of ways of doing this. A `foreach` loop on the list which adds a kvp to a dictionary. But I like terse code and wondered if there was a single line solution.


C# Convert List&lt;string&gt; to Dictionary&lt;string, string&gt;

I am curious why in Python a trailing comma in a list is valid syntax, and it seems that Python simply ignores it:

    &gt;&gt;&gt; [&#39;a&#39;,&#39;b&#39;,]
    [&#39;a&#39;, &#39;b&#39;]

It makes sense when its a tuple since `(&#39;a&#39;)` and `(&#39;a&#39;,)` are two different things, but in lists?



Why are trailing commas allowed in a list?

I have a list where each element is a 5*5 matrix. Eg


    [[1]]   
               V1          V2          V3          V4          V5      
          [1,]   0.000000   46.973700   21.453500  338.547000   10.401600 
          [2,]  43.020500    0.000000  130.652000  840.526000   56.363700 
          [3,]  12.605600  173.238000    0.000000  642.075000   19.628100 
          [4,] 217.946000  626.368000  481.329000    0.000000  642.341000 
          [5,] 217.946000  626.368000  481.329000    0.000000  642.341000 
    [[2]]   
               V1          V2          V3          V4          V5      
          [1,]   0.000000   47.973700   21.453500  338.547000   10.401600 
          [2,]  143.020500    0.000000  130.652000  840.526000   56.363700 
          [3,]  312.605600  17.238000    0.000000  642.075000   19.628100 
          [4,]  17.946000  126.368000  481.329000    0.000000  642.341000
          [5,] 217.946000  626.368000  481.329000    0.000000  642.341000  
    ...


 
How can I use an apply-like function to sum matrix [1] to [n],  and return a 5*5 matrix as a result (each element is a sum of the corresponding elements in each of the matrix in the list) ?

Sum a list of matrices

I have an array I&#39;d like to turn into a `List`, in order to modify the contents of the array.

Stack Overflow has plenty of questions/answers that address `Arrays.asList()` and how it only provides a List view of the underlying array, and how attempting to manipulate the resulting List will generally throw an `UnsupportedOperationException` as methods used to manipulate the list (e.g. `add()`, `remove()`, etc.) are not implemented by the List implementation provided by `Arrays.asList()`.

But I can&#39;t find an example of how to turn an array into a mutable List.  I suppose I can loop through the array and `put()` each value into a new List, but I&#39;m wondering if there&#39;s an interface that exists to do this for me.

Create mutable List from array?

I have got pretty simple list:

    example_list = [
        {&#39;points&#39;: 400, &#39;gold&#39;: 2480},
        {&#39;points&#39;: 100, &#39;gold&#39;: 610},
        {&#39;points&#39;: 100, &#39;gold&#39;: 620},
        {&#39;points&#39;: 100, &#39;gold&#39;: 620}
    ]

How can I sum all *gold* values? I&#39;m looking for nice oneliner.

Now I&#39;m using this code (but it&#39;s not the best solution):

    total_gold = 0
    for item in example_list:
        total_gold += example_list[&quot;gold&quot;]

Python - sum values in dictionary

Is there any difference in terms of performance between these two versions of the same query?

    --Version 1
    SELECT p.Name, s.OrderQty
    FROM Product p
    INNER JOIN SalesOrderDetail s on p.ProductID = s.ProductID

    --Version 2
    SELECT p.Name, s.OrderQty
    FROM Product p
    INNER JOIN (SELECT ProductID, OrderQty FROM SalesOrderDetail) s on p.ProductID = s.ProductID

I&#39;ve heard it said (by a DBA) that Version 2 is faster because it fetches, within the inner SELECT statement, only the columns that are required for the query. But that doesn&#39;t seem to make sense, since query performance (as I know) is based on number of rows affected and final list of columns returned.

The query plans for both are identical, so I&#39;m guessing there isn&#39;t any difference between the two. 

Am I correct?

INNER JOIN vs INNER JOIN (SELECT . FROM)

Just playing around with queries and examples to get a better understanding of joins.  I&#39;m noticing that in SQL Server 2008, the following two queries give the same results:

    SELECT * FROM TableA
    FULL OUTER JOIN TableB
    ON TableA.name = TableB.name
    


----------


    SELECT * FROM TableA
    FULL JOIN TableB
    ON TableA.name = TableB.name

Are these performing exactly the same action to produce the same results, or would I run into different results in a more complicated example?  Is this just interchangeable terminology?

FULL OUTER JOIN vs. FULL JOIN

I have a two tables,

Here is my first table,

    ID		SUBST_ID		CREATED_ID
    1		031938			TEST123
    2		930111			COOL123
    3		000391			THIS109
    4		039301			BRO1011
    5		123456			COOL938
    ...		...				...

This is my second table,
    
    ID		SERIAL_ID		BRANCH_ID
    1		039301			NULL
    2		000391			NULL
    3		123456			NULL
    ...		...				...

I need to some how update all rows within my second table using data from my first table.

It would need to do this all in one update query.

Both SUBST_ID and SERIAL_ID match, it needs to grab the created_id from the first table and insert it into the second table.

So the second table would become the following,

    ID		SERIAL_ID		BRANCH_ID
    1		039301			BRO1011
    2		000391			THIS109
    3		123456			COOL938
    ...		...				...

Thank you for your help and guidance.

MySQL update table based on another tables value

I&#39;m selecting two id columns but get error specified:

    org.hibernate.QueryException: **query specified join fetching, but the owner of the fetched association was not present in the select list** 

    [FromElement{explicit,not a collection join,fetch join,fetch non-lazy properties,classAlias=r,role=null,tableName=REVISIONS,tableAlias=revision1_,origin=ENTITY_CHANGED_IN_REVISION entitychan0_,columns={entitychan0_.REV_ID ,className=ru.csbi.registry.domain.envers.Revision}}] [ select ec.id as entityChangeId, r.id as revisionId from ru.csbi.registry.domain.envers.EntityChange as ec  inner join fetch ec.revision as r  where ec.groupEntityId = :groupEntityId and ec.groupName = :groupName  and r.timestamp &lt; :entityDateFrom  and r.timestamp &gt; :entityDateTo  and (  		ec.revisionType in (0, 5, 1, 4, 2 )  	  and not ( ec.otherGroupEntityModified = false and ec.thisGroupEntityModified = true and ec.rowDataModified = false and ec.collectionOfNotGroupEntityModified = false   )      )  group by ec.id, r.id  having count(*) &gt; :start order by r.id desc]

Some code:

    String hql = &quot; select ec.id as entityChangeId, r.id as revisionId from EntityChange as ec &quot; +
				&quot; inner join fetch ec.revision as r &quot; +
				&quot; where ec.groupEntityId = :groupEntityId&quot; +
				&quot; and ec.groupName = :groupName &quot; +
				&quot; and r.timestamp &lt; :entityDateFrom &quot; +
				&quot; and r.timestamp &gt; :entityDateTo &quot; +
				&quot; and ( &quot; +
				&quot; 		ec.revisionType in (&quot; + 
							RevisionType.ADD.getRepresentation() + &quot;, &quot; + 
							RevisionType.ONLY_DATA_PROPERTY_MOD.getRepresentation() + &quot;, &quot; +
							RevisionType.BOTH_COLLECTION_AND_PROPERTY_MOD.getRepresentation() + &quot;, &quot; +
							RevisionType.ONLY_COLLECTION_PROPERTY_MOD.getRepresentation() + &quot;, &quot; +
							RevisionType.DEL.getRepresentation() +
						&quot; ) &quot; +
				&quot; 	  and not ( &quot;+
						&quot;ec.otherGroupEntityModified = false and &quot; +
						&quot;ec.thisGroupEntityModified = true and &quot; +
						&quot;ec.rowDataModified = false and &quot; +
						&quot;ec.collectionOfNotGroupEntityModified = false &quot; +
					&quot;  ) &quot; +
				&quot;     ) &quot; +
				&quot; group by ec.id, r.id &quot; +
				&quot; having count(*) &gt; :start&quot; +
				&quot; order by r.id desc&quot;;

How to fix the error and what am I doing wrong?

query specified join fetching, but the owner of the fetched association was not present in the select list

This is a bit of a philosophical question about data.table join syntax. I am finding more and more uses for data.tables, but still learning...

The join format `X[Y]` for data.tables is very concise, handy and efficient, but as far as I can tell, it only supports inner joins and right outer joins. To get a left or full outer join, I need to use `merge`:

 - `X[Y, nomatch = NA]` -- all rows in Y -- right outer join  (default)
 - `X[Y, nomatch = 0]` -- only rows with matches in both X and Y -- inner join
 - `merge(X, Y, all = TRUE)` -- all rows from both X and Y -- full outer join
 - `merge(X, Y, all.x = TRUE)` -- all rows in X -- left outer join

It seems to me that it would be handy if the `X[Y]` join format supported all 4 types of joins. Is there a reason only two types of joins are supported?

For me, the `nomatch = 0` and `nomatch = NA` parameter values are not very intuitive for the actions being performed. It is easier for me to understand and remember the `merge` syntax: `all = TRUE`, `all.x = TRUE` and `all.y = TRUE`. Since the `X[Y]` operation resembles `merge` much more than `match`, why not use the `merge` syntax for joins rather than the `match` function&#39;s `nomatch` parameter?

Here are code examples of the 4 join types:

    # sample X and Y data.tables
    library(data.table)
    X &lt;- data.table(t = 1:4, a = (1:4)^2)
    setkey(X, t)
    X
    #    t  a
    # 1: 1  1
    # 2: 2  4
    # 3: 3  9
    # 4: 4 16
    
    Y &lt;- data.table(t = 3:6, b = (3:6)^2)
    setkey(Y, t)
    Y
    #    t  b
    # 1: 3  9
    # 2: 4 16
    # 3: 5 25
    # 4: 6 36

    # all rows from Y - right outer join
    X[Y]  # default
    #  t  a  b
    # 1: 3  9  9
    # 2: 4 16 16
    # 3: 5 NA 25
    # 4: 6 NA 36
    
    X[Y, nomatch = NA]  # same as above
    #    t  a  b
    # 1: 3  9  9
    # 2: 4 16 16
    # 3: 5 NA 25
    # 4: 6 NA 36
    
    merge(X, Y, by = &quot;t&quot;, all.y = TRUE)  # same as above
    #    t  a  b
    # 1: 3  9  9
    # 2: 4 16 16
    # 3: 5 NA 25
    # 4: 6 NA 36
    
    identical(X[Y], merge(X, Y, by = &quot;t&quot;, all.y = TRUE))
    # [1] TRUE
 
    # only rows in both X and Y - inner join
    X[Y, nomatch = 0]  
    #    t  a  b
    # 1: 3  9  9
    # 2: 4 16 16
    
    merge(X, Y, by = &quot;t&quot;)  # same as above
    #    t  a  b
    # 1: 3  9  9
    # 2: 4 16 16
    
    merge(X, Y, by = &quot;t&quot;, all = FALSE)  # same as above
    #    t  a  b
    # 1: 3  9  9
    # 2: 4 16 16
    
    identical( X[Y, nomatch = 0], merge(X, Y, by = &quot;t&quot;, all = FALSE) )
    # [1] TRUE

    # all rows from X - left outer join
    merge(X, Y, by = &quot;t&quot;, all.x = TRUE)
    #    t  a  b
    # 1: 1  1 NA
    # 2: 2  4 NA
    # 3: 3  9  9
    # 4: 4 16 16
 
    # all rows from both X and Y - full outer join
    merge(X, Y, by = &quot;t&quot;, all = TRUE)
    #    t  a  b
    # 1: 1  1 NA
    # 2: 2  4 NA
    # 3: 3  9  9
    # 4: 4 16 16
    # 5: 5 NA 25
    # 6: 6 NA 36

Update: data.table v1.9.6 introduced the `on=` syntax, which allows ad hoc joins on fields other than the primary key. [jangorecki&#39;s answer][1] to the question [How to join (merge) data frames (inner, outer, left, right)?][2] provides some examples of additional join types that data.table can handle.


  [1]: https://stackoverflow.com/a/34219998/1694807
  [2]: https://stackoverflow.com/q/1299871/1694807

Why does X[Y] join of data.tables not allow a full outer join, or a left join?

Which one should one use to hide microcommits?

Is the only difference between `git merge --squash` and `git merge --no-ff --no-commit` the denial of the other parents? 


What are the differences between `--squash` and `--no-ff --no-commit`?

I have a branch &#39;firstproject&#39; with 2 commits. I want to get rid of these commits and make them appear as a single commit. 

The command `git merge --squash` sounds promising, but when I run `git merge --squash` my terminal just brings up options for the command. What is the correct command? 

    Commit 1:
    Added &#39;homepage.html&#39;
    Added &#39;contacts.html&#39;

    Commit 2:
    Added &#39;homepage.php&#39;
    Added &#39;homepage.php&#39;
    Deleted &#39;homepage.html&#39;
    Deleted &#39;contacts.html&#39;



How can I combine two commits into one commit?

- I made some changes
- I submitted a pull request
- The pull request was accepted and merged. 
- We found a bug
- The changes were removed again (force push to 1 commit before) whilst I fixed the bug.

I&#39;ve now fixed the bug and want to resubmit the pull request with 1 extra commit. Is there any way to reopen the pull request or update it, or do I have to create a new pull request, type out the description etc again? Gitorious has this feature and we&#39;ve recently moved to GitHub.

GitHub: Reopening a merged pull request

I have two pandas dataframes:
    
    from pandas import DataFrame
    df1 = DataFrame({&#39;col1&#39;:[1,2],&#39;col2&#39;:[3,4]})
    df2 = DataFrame({&#39;col3&#39;:[5,6]})     

What is the best practice to get their cartesian product (of course without writing it explicitly like me)?

    #df1, df2 cartesian product
    df_cartesian = DataFrame({&#39;col1&#39;:[1,2,1,2],&#39;col2&#39;:[3,4,3,4],&#39;col3&#39;:[5,5,6,6]})


cartesian product in pandas

I am aware that one can merge (join) two `data.table` with the `merge` function or the `[.data.table` function.  However, if I have say 10, `data.table`s and want to use `do.call` to merge them all together, is there a function that would do this? Currently I resort to `do.call(cbind, ...)` which works for only very special cases.

Content Type	Original Author	Original Content on Stackoverflow
Question	user1452759	View Question on Stackoverflow
Solution 1 - Python	Rakesh	View Answer on Stackoverflow
Solution 2 - Python	BrenBarn	View Answer on Stackoverflow
Solution 3 - Python	Scotty	View Answer on Stackoverflow

How to merge multiple lists into one list in python?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

How to automatically crop and center an image

SQL order string as number

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