The [Array#take][1] method is probably what you want.

    [&#39;one&#39;,&#39;two&#39;,&#39;three&#39;].take(2)


  [1]: http://www.ruby-doc.org/core-1.9.2/Enumerable.html#method-i-take

You have [Array#first][1]:

    [&#39;one&#39;,&#39;two&#39;,&#39;three&#39;].first(2)
    =&gt; [&#39;one&#39;, &#39;two&#39;]


  [1]: http://www.ruby-doc.org/core-1.9.2/Array.html#method-i-first

    irb(main):001:0&gt; [1,2,3,4,5].slice! 0,4
    =&gt; [1, 2, 3, 4]

Just another way to do it.

I have a data frame, which looks like that: 

        P1  P2  P3  T1  T2  T3  I1  I2
    1   2   3   5   52  43  61  6   &quot;b&quot;
    2   6   4   3   72  NA  59  1   &quot;a&quot;
    3   1   5   6   55  48  60  6   &quot;f&quot;
    4   2   4   4   65  64  58  2   &quot;b&quot;

I want to sort it by I1 in descending order, and rows with the same value in I1 by I2 in ascending order, getting the rows in the order `1 3 4 2`. But the `order` function seems to only take one `decreasing` argument, which is then `TRUE` or `FALSE` for all ordering vectors at once. How do I get my sort correct?



How to order a data frame by one descending and one ascending column?

I&#39;m currently trying to right align the logging level field in my Python logger so that output such as:

    [2011-10-14 13:47:51] [DEBUG] --- starting... (smtphandlers.py:96)
    [2011-10-14 13:47:51] [INFO] --- first things first... (smtphandlers.py:97)
    [2011-10-14 13:47:51] [WARNING] --- about to end... (smtphandlers.py:98)
    [2011-10-14 13:47:51] [DEBUG] --- ending (smtphandlers.py:99)

instead looks like:

    [2011-10-14 13:47:51] [   DEBUG] --- starting... (smtphandlers.py:96)
    [2011-10-14 13:47:51] [    INFO] --- first things first... (smtphandlers.py:97)
    [2011-10-14 13:47:51] [ WARNING] --- about to end... (smtphandlers.py:98)
    [2011-10-14 13:47:51] [   DEBUG] --- ending (smtphandlers.py:99)

The format line for the first block is:

    logging.Formatter(&quot;[%(asctime)s] [%(levelname)s] --- %(message)s (%(filename)s:%(lineno)s)&quot;, &quot;%Y-%m-%d %H:%M:%S&quot;)

If I know the max level length is 8 (eg: CRITICAL), then I&#39;ll right align to 8 spaces.
I&#39;m trying to figure out how to achieve this.  The following fails because &quot;%(levelname)s&quot; is more than 8 characters (the substitution doesn&#39;t happen until later).  If I use something like &quot;{0:&gt;20}&quot;.format&quot;%(levelname)s&quot;, then it works, but that is more padding than I need or want.

    logging.Formatter(&quot;[%(asctime)s] [&quot; + &quot;{0:&gt;8}&quot;.format&quot;%(levelname)s&quot; + &quot;] --- %(message)s (%(filename)s:%(lineno)s)&quot;, &quot;%Y-%m-%d %H:%M:%S&quot;)

Short of subclassing Formatter, anyone have a way to achieve this?

How to right align level field in Python logging.Formatter

I want to limit an Array object. How is this possible with ruby


    [&#39;one&#39;,&#39;two&#39;,&#39;three&#39;].limit(2) =&gt; [&#39;one&#39;,&#39;two&#39;]

Thanks for your quick help!

Ruby Array limit method

I want to limit an Array object. How is this possible with ruby
<pre><code class="hljs language-scss">['one','two','three'].limit(2) => ['one','two']
</code></pre>
Thanks for your quick help!

I use `rvm` to manage different rubies and their gemsets. My shell is zsh with oh-my-zsh configured with basic settings. Enabled oh-my-zsh plugins are ruby, rails, osx, and git. Here&#39;s the command I used to install ruby-1.8.7 and rails-3.0.7.

    rvm install 1.8.7
    rvm use 1.8.7
    gem install rails -v=3.0.7

and then I typed `rails` and got:

    Rails is not currently installed on this system. To get the latest version, simply type:

        $ sudo gem install rails

    You can then rerun your &quot;rails&quot; command.

I&#39;ve tried more thorough installs also, Like reinstall `rubygems` after switching to ruby-1.8.7, or create a completely new gemset, but with no luck.

Here&#39;s the rvm info:


    ruby-1.8.7-p352@rails:
    
      system:
        uname:       &quot;Darwin yicai.local 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun  7 16:32:41 PDT 2011; root:xnu-1504.15.3~1/RELEASE_X86_64 x86_64&quot;
        bash:        &quot;/bin/bash =&gt; GNU bash, version 3.2.48(1)-release (x86_64-apple-darwin10.0)&quot;
        zsh:         &quot;/bin/zsh =&gt; zsh 4.3.9 (i386-apple-darwin10.0)&quot;
    
      rvm:
        version:      &quot;rvm 1.8.6 by Wayne E. Seguin (wayneeseguin@gmail.com) [https://rvm.beginrescueend.com/]&quot;
    
      ruby:
        interpreter:  &quot;ruby&quot;
        version:      &quot;1.8.7&quot;
        date:         &quot;2011-06-30&quot;
        platform:     &quot;i686-darwin10.8.0&quot;
        patchlevel:   &quot;2011-06-30 patchlevel 352&quot;
        full_version: &quot;ruby 1.8.7 (2011-06-30 patchlevel 352) [i686-darwin10.8.0]&quot;
    
      homes:
        gem:          &quot;/Users/nil/.rvm/gems/ruby-1.8.7-p352@rails&quot;
        ruby:         &quot;/Users/nil/.rvm/rubies/ruby-1.8.7-p352&quot;
    
      binaries:
        ruby:         &quot;/Users/nil/.rvm/rubies/ruby-1.8.7-p352/bin/ruby&quot;
        irb:          &quot;/Users/nil/.rvm/rubies/ruby-1.8.7-p352/bin/irb&quot;
        gem:          &quot;/Users/nil/.rvm/rubies/ruby-1.8.7-p352/bin/gem&quot;
        rake:         &quot;/Users/nil/.rvm/bin/rake&quot;
    
      environment:
        PATH:         &quot;/Users/nil/.rvm/gems/ruby-1.8.7-p352@rails/bin:/Users/nil/.rvm/gems/ruby-1.8.7-p352@global/bin:/Users/nil/.rvm/rubies/ruby-1.8.7-p352/bin:/Users/nil/.rvm/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/usr/local/sbin&quot;
        GEM_HOME:     &quot;/Users/nil/.rvm/gems/ruby-1.8.7-p352@rails&quot;
        GEM_PATH:     &quot;/Users/nil/.rvm/gems/ruby-1.8.7-p352@rails:/Users/nil/.rvm/gems/ruby-1.8.7-p352@global&quot;
        MY_RUBY_HOME: &quot;/Users/nil/.rvm/rubies/ruby-1.8.7-p352&quot;
        IRBRC:        &quot;/Users/nil/.rvm/rubies/ruby-1.8.7-p352/.irbrc&quot;
        RUBYOPT:      &quot;&quot;
        gemset:       &quot;rails&quot;
    
and the gem version is 1.8.10, the latest.

Rails keeps telling me that it&#39;s not currently installed

How do you convert a Unix timestamp (seconds since epoch) to Ruby DateTime?

How to convert a unix timestamp (seconds since epoch) to Ruby DateTime?

How can I set an object attribute dynamically in Ruby e.g. 




    def set_property(obj, prop_name, prop_value)
        #need to do something like &gt; obj.prop_name = prop_value 
    
        #we can use eval but I&#39;ll prefer a faster/cleaner alternative:
        eval &quot;obj.#{prop_name} = #{prop_value}&quot;
    end



Set Attribute Dynamically of Ruby Object

I need validate some attributes ONLY if they are not empty. 

For example the user may have a logo. If we try to load it - validation should work. If we simply update the user&#39;s data without the logo, validation must be skipped.

Now i have:

The form has a choice of two files. One - logo, second - avatar.
Both of this attributes is part of User model. In User model a have validation:

    validates_preference_of :logo_file_name, :message=&gt;I18n.t(&quot;...&quot;)
    validates_format_of :logo_file_name, :with=&gt;/\.(jpeg|jpg|png|gif)$/i, :message=&gt; I18n.t(&quot;...&quot;)
    validates_preference_of :avatar_file_name, :message=&gt;I18n.t(&quot;...&quot;)
    validates_format_of :avatar_file_name, :with=&gt;/\.(jpeg|jpg|png|gif)$/i, :message=&gt; I18n.t(&quot;...&quot;)

In this case, if we try to create a new User without selected logo and avatar, we will have errors (our validation). I tryed change validation and add &quot;:on =&gt; :update&quot; like this:

    validates_preference_of :logo_file_name, :message=&gt;I18n.t(&quot;...&quot;), :on =&gt; :update
    validates_format_of :logo_file_name, :with=&gt;/\.(jpeg|jpg|png|gif)$/i, :message=&gt; I18n.t(&quot;...&quot;), :on =&gt; :update
    validates_preference_of :avatar_file_name, :message=&gt;I18n.t(&quot;...&quot;), :on =&gt; :update
    validates_format_of :avatar_file_name, :with=&gt;/\.(jpeg|jpg|png|gif)$/i, :message=&gt; I18n.t(&quot;...&quot;), :on =&gt; :update

Now i can create user without selected logo and avatar, but if i try edit user and try upload only logo - i have validation errors of avatar. If i choose file for avatar and logo leave blank - i have validation errors for logo.

How i can run validation ony for attribute that I want to change?

Validate attribute only if it present (only if user fill in it)

After updating a bundle, you will have some gems that may be obsolete -- since a newer version of that gem has been installed. There is no such command under the `bundle` executable i.e. `bundle clean`. How does one get rid of these obsolete gems?

This is an attempt to reduce slug size in my rails app.

rails bundle clean

I can&#39;t add an element of type `T` into a list `List[T]`.
I tried with `myList ::= myElement` but it seems it creates a strange object and accessing to `myList.last` always returns the first element that was put inside the list. How can I solve this problem?

Appending an element to the end of a list in Scala

I&#39;d like to compare two arrays... ideally, efficiently. Nothing fancy, just `true` if they are identical, and `false` if not. Not surprisingly, the comparison operator doesn&#39;t seem to work.

    var a1 = [1,2,3];
    var a2 = [1,2,3];
    console.log(a1==a2);    // Returns false
    console.log(JSON.stringify(a1)==JSON.stringify(a2));    // Returns true

JSON encoding each array does, but is there a faster or &quot;better&quot; way to simply compare arrays without having to iterate through each value?

How to compare arrays in JavaScript?

In my MVC application, I am using following code to upload a file.

**MODEL**

     public HttpPostedFileBase File { get; set; }

**VIEW**

    @Html.TextBoxFor(m =&gt; m.File, new { type = &quot;file&quot; })


Everything working fine .. But I am trying to convert the result fiel to byte[] .How can i  do this

**CONTROLLER**

     public ActionResult ManagePhotos(ManagePhotos model)
        {
            if (ModelState.IsValid)
            {
                byte[] image = model.File; //Its not working .How can convert this to byte array
            }
         }

Convert HttpPostedFileBase to byte[]

If I have an array like this:

    var arr = [&#39;one&#39;,&#39;two&#39;,&#39;three&#39;];

I can access different parts by doing this:

    console.log(arr[1]);

How can I access object properties by their order rather than by key?

Example:

    var obj = {
        &#39;something&#39; : &#39;awesome&#39;,
        &#39;evenmore&#39;  : &#39;crazy&#39;
    },
    jbo = {
        &#39;evenmore&#39;  : &#39;crazy&#39;,
        &#39;something&#39; : &#39;awesome&#39;
    };

How would I get the first property for each object–&quot;something&quot; from `obj` and &quot;evenmore&quot; from `jbo`–without explicitly using the property name?

Now, a few of you seem to think I&#39;m after something like:

    console.log(obj[&#39;something&#39;]);

This is not the case, I&#39;m specifically looking to target the index, just like the first example - if it&#39;s possible.

Access non-numeric Object properties by index?

I have this string array:

    string[] stringArray = { &quot;text1&quot;, &quot;text2&quot;, &quot;text3&quot;, &quot;text4&quot; };
    string value = &quot;text3&quot;;
    
I would like to determine if `stringArray` contains `value`. If so, I want to locate its position in the array. 

I don&#39;t want to use loops. Can anyone suggest how I might do this?

Content Type	Original Author	Original Content on Stackoverflow
Question	Kieran Klaassen	View Question on Stackoverflow
Solution 1 - Ruby	Larsenal	View Answer on Stackoverflow
Solution 2 - Ruby	rubyprince	View Answer on Stackoverflow
Solution 3 - Ruby	kojaktsl	View Answer on Stackoverflow

Ruby Array limit method

Ruby Problem Overview

Ruby Solutions

Solution 1 - Ruby

Solution 2 - Ruby

Solution 3 - Ruby

How to right align level field in Python logging.Formatter

How to order a data frame by one descending and one ascending column?

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