How about [mkString][1] ?

    theStrings.mkString(&quot;,&quot;)

A variant exists in which you can specify a prefix and suffix too.

See [here][2] for an implementation using [foldLeft][3], which is much more verbose, but perhaps worth looking at for education&#39;s sake.


  [1]: http://www.scala-lang.org/api/2.7.5/scala/Iterable.html#mkString%28String%29
  [2]: https://web.archive.org/web/20171015150340/http://langref.org/scala/lists/output/join-the-elements-of-a-list-separated-by-commas
  [3]: http://oldfashionedsoftware.com/2009/07/10/scala-code-review-foldleft-and-foldright/

Recently I started using Python3 and it&#39;s lack of `xrange` hurts.

Simple example:

1. Python2:

       from time import time as t
       def count():
         st = t()
         [x for x in xrange(10000000) if x%4 == 0]
         et = t()
         print et-st
       count()

2. Python3:

       from time import time as t
    
       def xrange(x):
    
           return iter(range(x))
    
       def count():
           st = t()
           [x for x in xrange(10000000) if x%4 == 0]
           et = t()
           print (et-st)
       count()

The results are, respectively:
1. `1.53888392448`
2. `3.215819835662842`

Why is that? I mean, why `xrange` has been removed? It&#39;s such a great tool to learn. For the beginners, just like myself, like we all were at some point. Why remove it? Can somebody point me to the proper PEP, I can&#39;t find it.

Why is there no xrange function in Python3?

I have a site with many pages and different background pictures, and I display them from CSS like:

&lt;!-- language-all: lang-css --&gt;
    
    body.page-8 {
	    background: url(&quot;../img/pic.jpg&quot;) no-repeat scroll center top #000;
	    background-size: cover;
    }

However, I want to show different (fullscreen) pictures on one page using `&lt;img&gt;` elements, and I want them to have the same properties as the above  `background-image: cover;` property (the images cant be displayed from CSS, they must be displayed from the HTML document).

Normally I use:

    div.mydiv img {
	    width: 100%;
    }

Or:

    div.mydiv img {
	    width: auto;
    }

to make the picture full and responsive. However the picture shrinks too much (`width: 100%`) when the screen gets too narrow, and shows the body&#39;s background-color in the bottom screen. The other method, `width: auto;`, only makes the image full size and does not respond to the screen size.

Is there a way to display the image the same way that `background-size: cover` does?

Is there an equivalent to background-size: cover and contain for image elements?

How do I &quot;join&quot; an iterable of strings by another string in Scala?

    val thestrings = Array(&quot;a&quot;,&quot;b&quot;,&quot;c&quot;)
    val joined = ???
    println(joined)

I want this code to output `a,b,c` (join the elements by &quot;,&quot;).

Scala: join an iterable of strings

How do I "join" an iterable of strings by another string in Scala?
<pre><code class="hljs language-ini">val thestrings = Array("a","b","c")
val joined = ???
println(joined)
</code></pre>
I want this code to output <code>a,b,c</code> (join the elements by ",").

This does not work and I need it badly

    $(&#39;some+multi+word+string&#39;).replace(&#39;+&#39;, &#39; &#39; );

always gets

    some multi+word+string

it&#39;s always replacing for the first instance only, but I need it to work for all + symbols.


jQuery - replace all instances of a character in a string

What would be the most efficient way to check whether a string contains a &quot;.&quot; or not?

I know you can do this in many different ways like with [regular expressions][1] or loop through the string to see if it contains a dot (&quot;.&quot;).

  [1]: http://en.wikipedia.org/wiki/Regular_expression


PHP string &quot;contains&quot;

Here is how I check whether `mystring` begins with some string:

    &gt;&gt;&gt; mystring.lower().startswith(&quot;he&quot;)
    True

The problem is that `mystring` is very long (thousands of characters), so the `lower()` operation takes a lot of time.

**QUESTION:** Is there a more efficient way?

My unsuccessful attempt:

    &gt;&gt;&gt; import re;
    &gt;&gt;&gt; mystring.startswith(&quot;he&quot;, re.I)
    False


Case-insensitive string startswith in Python

Is it possible to get the object property name as a string

    person = {};
    person.first_name = &#39;Jack&#39;;
    person.last_name = &#39;Trades&#39;;
    person.address = {};
    person.address.street = &#39;Factory 1&#39;;
    person.address.country = &#39;USA&#39;;

I&#39;d like to use it like this:

    var pn = propName( person.address.country ); // should return &#39;country&#39; or &#39;person.address.country&#39;
    var pn = propName( person.first_name );      // should return &#39;first_name&#39; or &#39;person.first_name&#39;


**NOTE**: this code is exactly what I&#39;m looking for. I understand it sounds even stupid, but it&#39;s not.

This is what I want to do with it.

HTML
    &lt;input type=&quot;text&quot; value=&quot;Jack&quot; id=&quot;id_first_name &quot;/&gt;

    person = {};
    person.id_first_name = &#39;Jack&#39;;
    person.id_last_name = &#39;Trades&#39;;
    person.address = {};
    person.address.id_address = &#39;Factory 1&#39;;
    person.address.id_country = &#39;USA&#39;;


    extPort.postMessage
    (
      {
        message : MSG_ACTION,
        propName( person.first_name ): person.first_name
      }
    };

----------------------**ANSWER**-----------------------

Got it thanks to ibu. He pointed the right way and I used a recursive function

    var res = &#39;&#39;;
    
    function propName(prop, value) {
    	for (var i in prop) {
    		if (typeof prop[i] == &#39;object&#39;) {
    			if (propName(prop[i], value)) {
    				return res;
    			}
    		} else {
    			if (prop[i] == value) {
    				res = i;
    				return res;
    			}
    		}
    	}
    	return undefined;
    }
    
    var pn = propName(person, person.first_name); // returns &#39;first_name&#39;
    var pn = propName(person, person.address.country); // returns &#39;country&#39;

DEMO: http://jsbin.com/iyabal/1/edit

Get object property name as a string

I am trying to write a text game and I have run into an error in the function I am defining that lets you basically spend your skill points after you make your character. At first, the error stated that I was attempting to subtract a string from an integer in this part of the code:`balance - strength`. Obviously that was wrong so I fixed it with `strength = int(strength)`... but now I am getting this error which I have never seen before(new programmer) and I am stumped on what exactly it is trying to tell me and how I fix it.

Here is my code for the part of the function that isn&#39;t working:

    def attributeSelection():
        balance = 25
        print(&quot;Your SP balance is currently 25.&quot;)
        strength = input(&quot;How much SP do you want to put into strength?&quot;)
        strength = int(strength)
        balanceAfterStrength = balance - strength
        if balanceAfterStrength == 0:
            print(&quot;Your SP balance is now 0.&quot;)
            attributeConfirmation()
        elif strength &lt; 0:
            print(&quot;That is an invalid input. Restarting attribute selection. Keep an eye on your balance this time!&quot;)
            attributeSelection()
        elif strength &gt; balance:
            print(&quot;That is an invalid input. Restarting attribute selection. Keep an eye on your balance this time!&quot;)
            attributeSelection()
        elif balanceAfterStrength &gt; 0 and balanceAfterStrength &lt; 26:
            print(&quot;Ok. You&#39;re balance is now at &quot; + balanceAfterStrength + &quot; skill points.&quot;)
        else:
            print(&quot;That is an invalid input. Restarting attribute selection.&quot;)
            attributeSelection()

And here is the error I get when I get to this part of the code in the shell:


        Your SP balance is currently 25.
    How much SP do you want to put into strength?5
    Traceback (most recent call last):
      File &quot;C:\Python32\APOCALYPSE GAME LIBRARY\apocalypseGame.py&quot;, line 205, in &lt;module&gt;
        gender()
      File &quot;C:\Python32\APOCALYPSE GAME LIBRARY\apocalypseGame.py&quot;, line 22, in gender
        customizationMan()
      File &quot;C:\Python32\APOCALYPSE GAME LIBRARY\apocalypseGame.py&quot;, line 54, in customizationMan
        characterConfirmation()
      File &quot;C:\Python32\APOCALYPSE GAME LIBRARY\apocalypseGame.py&quot;, line 93, in characterConfirmation
        characterConfirmation()
      File &quot;C:\Python32\APOCALYPSE GAME LIBRARY\apocalypseGame.py&quot;, line 85, in characterConfirmation
        attributeSelection()
      File &quot;C:\Python32\APOCALYPSE GAME LIBRARY\apocalypseGame.py&quot;, line 143, in attributeSelection
        print(&quot;Ok. You&#39;re balance is now at &quot; + balanceAfterStrength + &quot; skill points.&quot;)
    TypeError: Can&#39;t convert &#39;int&#39; object to str implicitly

Does anyone know how to solve this? Thanks ahead.

TypeError: Can&#39;t convert &#39;int&#39; object to str implicitly

Both types `Unit` and `Nothing` indicate a function that does not return anything. What&#39;s the difference between them?

What&#39;s the difference between Unit and Nothing?

In his talk [Simple Made Easy][1], Rick Hickey talks about &quot;**Polymorphism a la carte**&quot; (about 30:00 into the video). In the same context, he also mentions Haskell&#39;s [Type Classes][2] and Clojure&#39;s [Multi-Methods][3] (and protocols).

Since I am not very familiar with these concepts, I would like to understand its usefulness when trying to achieve **simplicity**. I am particularly interested in any examples or showcases of this concept in **Scala**. 


  [1]: http://www.infoq.com/presentations/Simple-Made-Easy
  [2]: http://en.wikipedia.org/wiki/Type_class
  [3]: http://en.wikipedia.org/wiki/Multiple_dispatch

What is &quot;polymorphism a la carte&quot; and how can I benefit from it?

I am trying to parse a CSV file, ideally using weka.core.converters.CSVLoader.
However the file I have is not a valid UTF-8 file.
It is mostly a UTF-8 file but some of the field values are in different encodings,
so there is no encoding in which the whole file is valid,
but I need to parse it anyway.
Apart from using java libraries like Weka, I am mainly working in Scala.
I am not even able to read the file usin scala.io.Source:
For example

    Source.
      fromFile(filename)(&quot;UTF-8&quot;).
      foreach(print);

throws:

        java.nio.charset.MalformedInputException: Input length = 1
	at java.nio.charset.CoderResult.throwException(CoderResult.java:277)
	at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:337)
	at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:176)
	at java.io.InputStreamReader.read(InputStreamReader.java:184)
	at java.io.BufferedReader.fill(BufferedReader.java:153)
	at java.io.BufferedReader.read(BufferedReader.java:174)
	at scala.io.BufferedSource$$anonfun$iter$1$$anonfun$apply$mcI$sp$1.apply$mcI$sp(BufferedSource.scala:38)
	at scala.io.Codec.wrap(Codec.scala:64)
	at scala.io.BufferedSource$$anonfun$iter$1.apply(BufferedSource.scala:38)
	at scala.io.BufferedSource$$anonfun$iter$1.apply(BufferedSource.scala:38)
	at scala.collection.Iterator$$anon$14.next(Iterator.scala:150)
	at scala.collection.Iterator$$anon$25.hasNext(Iterator.scala:562)
	at scala.collection.Iterator$$anon$19.hasNext(Iterator.scala:400)
	at scala.io.Source.hasNext(Source.scala:238)
	at scala.collection.Iterator$class.foreach(Iterator.scala:772)
	at scala.io.Source.foreach(Source.scala:181)

I am perfectly happy to throw all the invalid characters away or replace them with some dummy.
I am going to have lots of text like this to process in various ways
and may need to pass the data to various third party libraries.
An ideal solution would be some kind of global setting that would
cause all the low level java libraries to ignore invalid bytes in text,
so that that I can call third party libraries on this data without modification.

SOLUTION:

    import java.nio.charset.CodingErrorAction
    import scala.io.Codec

    implicit val codec = Codec(&quot;UTF-8&quot;)
    codec.onMalformedInput(CodingErrorAction.REPLACE)
    codec.onUnmappableCharacter(CodingErrorAction.REPLACE)

    val src = Source.
      fromFile(filename).
      foreach(print)


Thanks to +Esailija for pointing me in the right direction.
This lead me to https://stackoverflow.com/questions/3801890/how-to-detect-illegal-utf-8-byte-sequences-to-replace-them-in-java-inputstream
which provides the core java solution. In Scala I can make this the default behaviour by making the codec implicit. I think I can make it the default behaviour for the entire package by putting it the implicit codec definition in the package object.



How to read a text file with mixed encodings in Scala or Java?

I&#39;m using [Slick][1] with a [Play Framework][2] 2.1 and I have some troubles.

Given the following entity...

    package models

    import scala.slick.driver.PostgresDriver.simple._

    case class Account(id: Option[Long], email: String, password: String)

    object Accounts extends Table[Account](&quot;account&quot;) {
      def id = column[Long](&quot;id&quot;, O.PrimaryKey, O.AutoInc)
      def email = column[String](&quot;email&quot;)
      def password = column[String](&quot;password&quot;)
      def * = id.? ~ email ~ password &lt;&gt; (Account, Account.unapply _)
    }

...I have to import a package for a *specific* database driver, but I want to use **H2** for **testing** and **PostgreSQL** in **production**. How should I proceed?

I was able to workaround this by *overriding* the driver settings in my unit test:

    package test

    import org.specs2.mutable._
 
    import play.api.test._
    import play.api.test.Helpers._

    import scala.slick.driver.H2Driver.simple._
    import Database.threadLocalSession
 
    import models.{Accounts, Account}
 
    class AccountSpec extends Specification {

      &quot;An Account&quot; should {
        &quot;be creatable&quot; in {
          Database.forURL(&quot;jdbc:h2:mem:test1&quot;, driver = &quot;org.h2.Driver&quot;) withSession {
            Accounts.ddl.create                                                                                                                                          
            Accounts.insert(Account(None, &quot;user@gmail.com&quot;, &quot;Password&quot;))
            val account = for (account &lt;- Accounts) yield account
            account.first.id.get mustEqual 1
          }
        }
      }
    }

I don&#39;t like this solution and I&#39;m wondering if there is an elegant way to write DB-agnostic code so there are two different database engines used - one in testing and another in production?

I don&#39;t want to use evolution, either, and prefer to let Slick create the database tables for me:

    import play.api.Application
    import play.api.GlobalSettings
    import play.api.Play.current
    import play.api.db.DB
 
    import scala.slick.driver.PostgresDriver.simple._
    import Database.threadLocalSession
                                                                                                                
    import models.Accounts

    object Global extends GlobalSettings {
 
      override def onStart(app: Application) {
        lazy val database = Database.forDataSource(DB.getDataSource())
 
        database withSession {
          Accounts.ddl.create
        }
      }
    }

The first time I start the application, everything works fine... then, of course, the second time I start the application it crashes because the tables already exist in the PostgreSQL database.

That said, my last two questions are:

 1. How can I determine whether or not the database tables already exist?
 2. How can I make the `onStart` method above DB-agnostic so that I can test my application with `FakeApplication`?

  [1]: http://slick.typesafe.com/
  [2]: https://www.playframework.com/

How to write database-agnostic Play application and perform first-time database initialization?

There is a relatively-new lightweight JVM called [Avian][1] that can produce executables for iOS targets.

There isn&#39;t too much documentation on the website (and not much can be found searching with Google). I was wondering if anybody was aware of a step-by-step tutorial on how to get a basic Scala program running on iOS, using [Avian][1].


  [1]: http://oss.readytalk.com/avian/

Content Type	Original Author	Original Content on Stackoverflow
Question	scala_newbie	View Question on Stackoverflow
Solution 1 - String	Brian Agnew	View Answer on Stackoverflow

Scala: join an iterable of strings

String Problem Overview

String Solutions

Solution 1 - String

Is there an equivalent to background-size: cover and contain for image elements?

Why is there no xrange function in Python3?

Attributions