How about this?

     &quot;1,112&quot;.delete(&#39;,&#39;).to_i


You may also want to make sure that your code localizes correctly, or make sure the users are used to the &quot;international&quot; notation. For example, &quot;1,112&quot; actually means different numbers across different countries. In Germany it means the number a little over one, instead of one thousand and something.

Corresponding Wikipedia article is at http://en.wikipedia.org/wiki/Decimal_mark. It seems to be poorly written at this time though. For example as a Chinese I&#39;m not sure where does these description about thousand separator in China come from.

Some more convenient

    &quot;1,1200.00&quot;.gsub(/[^0-9]/,&#39;&#39;) 

it makes &quot;1 200 200&quot; work properly aswell

The following is another method that will work, although as with some of the other methods it will strip decimal places.

    a = 1,112
    b = a.scan(/\d+/).join().to_i =&gt; 1112

I would do using [`String#tr`](http://ruby-doc.org/core-2.1.0/String.html#method-i-tr) :

    &quot;1,112&quot;.tr(&#39;,&#39;,&#39;&#39;).to_i # =&gt; 1112


If someone is looking to sub out more than a comma I&#39;m a fan of:

    &quot;1,200&quot;.chars.grep(/\d/).join.to_i

dunno about performance but, it is more flexible than a `gsub`, ie:

    &quot;1-200&quot;.chars.grep(/\d/).join.to_i
    





    String count = count.replace(&quot;,&quot;, &quot;&quot;);

`List.AddRange()` exists, but `IList.AddRange()` doesn&#39;t.  
This strikes me as odd. What&#39;s the reason behind this?

Why doesn&#39;t IList support AddRange

A Pandas `DataFrame` contains column named `&quot;date&quot;` that contains non-unique `datetime` values. 
I can group the lines in this frame using:

    data.groupby(data[&#39;date&#39;])

However, this splits the data by the `datetime` values. I would like to group these data by the year stored in the &quot;date&quot; column. [This page][1] shows how to group by year in cases where the time stamp is used as an index, which is not true in my case.

How do I achieve this grouping?

  [1]: http://wesmckinney.com/blog/?p=125

How to group pandas DataFrame entries by date in a non-unique column

Is there any neat method to convert &quot;1,112&quot; to integer 1112, instead of 1?

I&#39;ve got one, but not neat: 

    &quot;1,112&quot;.split(&#39;,&#39;).join.to_i #=&gt; 1112



Convert string with comma to integer

Is there any neat method to convert "1,112" to integer 1112, instead of 1?
I've got one, but not neat:
<pre><code class="hljs language-bash">"1,112".split(',').join.to_i #=> 1112
</code></pre>

Undefining a method in Ruby is pretty simple, I can just use `undef METHOD_NAME`.

Is there anything similar for a class? I am on `MRI 1.9.2`. 

I have to undefine an ActiveRecord Model, run two lines of code, and restore the model back to its original form.

The problem is, I have an model `Contact` and I am using a company&#39;s API and it happens that they have some class called `Contact`, and changing my model name would be lot of work for me. 

What can I do in this situation?

How to undefine class in Ruby?

I am trying to reference an association extension but it errors with:

    NameError (uninitialized constant User::ListerExtension):
      app/models/user.rb:2:in `&lt;class:User&gt;&#39;

Here is my implementation:

### app/models/user.rb

    class User &lt; ActiveRecord::Base
      include ListerExtension
      
      has_and_belongs_to_many :roles, :uniq =&gt; true, :extend =&gt; Lister

### lib/lister.rb

    module ListerExtension
      def lister
        self.map(&amp;:to_s).join(&#39;, &#39;)
      end
    end

I am using Rails v3.1.3.

&quot;Uninitialized constant&quot; error when including a module

Often I get hard to debug infinite recursions when coding ruby. Is there a way to get a backtrace out of a `SystemStackError` to find out, where exactly the infinite loop occurs?

## Example

Given some methods `foo`, `bar` and `baz` which call each other in a loop:

    def foo
      bar
    end
    
    def bar
      baz
    end
    
    def baz
      foo
    end

    foo

When I run this code, I just get the message `test.rb:6: stack level too deep (SystemStackError)`. It would be useful to get at least the last 100 lines of the stack, so I could immediately see this is a loop between `foo`, `bar` and `baz`, like this:

    test.rb:6: stack level too deep (SystemStackError)
      test.rb:2:in `foo&#39;
      test.rb:10:in `baz&#39;
      test.rb:6:in `bar&#39;
      test.rb:2:in `foo&#39;
      test.rb:10:in `baz&#39;
      test.rb:6:in `bar&#39;
      test.rb:2:in `foo&#39;
      [...]

Is there any way to accomplish this?

**EDIT:**

As you may see from the answer below, Rubinius can do it. Unfortunately some [rubinius bugs](http://github.com/rubinius/rubinius/issues/1692) prevent me from using it with the software I&#39;d like to debug. So to be precise the question is:

**How do I get a backtrace with MRI (the default ruby) 1.9?**


How to get a backtrace from a SystemStackError: stack level too deep?

In ruby, I understand that module functions can be made available without mixing in the module by using `module_function` as shown here. I can see how this is useful so you can use the function without mixing in the module.

    module MyModule
      def do_something
        puts &quot;hello world&quot;
      end
      module_function :do_something
    end


My question is though why you might want to have the function defined both of these ways.

Why not just have

    def MyModule.do_something

OR

    def do_something
    
In what kind of cases would it be useful to have the function available to be mixed in, or to be used as a static method?

ruby module_function vs including module

I&#39;m looking for a better way to do

    if hash.key? :a &amp;&amp;
       hash.key? :b &amp;&amp;
       hash.key? :c &amp;&amp;
       hash.key? :d

preferably something like

    hash.includes_keys? [ :a, :b, :c, :d ] 


I came up with 

    hash.keys &amp; [:a, :b, :c, :d] == [:a, :b, :c, :d]

but I dont like having to add the array twice though

Check if a hash&#39;s keys include all of a set of keys

&gt; **Possible Duplicate:**  
&gt; [Python &amp;ldquo;is&amp;rdquo; operator behaves unexpectedly with integers](https://stackoverflow.com/questions/306313/python-is-operator-behaves-unexpectedly-with-integers)  

&lt;!-- End of automatically inserted text --&gt;

Today I tried to debug my project and after a few hours of analysing I&#39;d got this:

    &gt;&gt;&gt; (0-6) is -6
    False

but,

    &gt;&gt;&gt; (0-5) is -5
    True

Could you explain to me, why?
Maybe this is some kind of bug or very strange behavior.

    &gt; Python 2.7.3 (default, Apr 24 2012, 00:00:54) [GCC 4.7.0 20120414 (prerelease)] on linux2
    &gt;&gt;&gt; type(0-6) 
    &lt;type &#39;int&#39;&gt;
    &gt;&gt;&gt; type(-6) 
    &lt;type &#39;int&#39;&gt;
    &gt;&gt;&gt; type((0-6) is -6)
    &lt;type &#39;bool&#39;&gt;
    &gt;&gt;&gt; 



Why (0-6) is -6 = False?

How do I convert the **integer** value &quot;45&quot; into the **string** value &quot;45&quot; in Excel VBA?

How Do I Convert an Integer to a String in Excel VBA?

I have this python program that adds strings to integers:

    a = raw_input(&quot;Enter a: &quot;)
    b = raw_input(&quot;Enter b: &quot;)
    print &quot;a + b as strings: &quot; + a + b
    a = int(a)
    b = int(b)
    c = a + b
    str(c)
    print &quot;a + b as integers: &quot; + c

I get this error:

    Python: TypeError: cannot concatenate &#39;str&#39; and &#39;int&#39; objects

How can I add strings to integers?

Python: TypeError: cannot concatenate &#39;str&#39; and &#39;int&#39; objects

Given a list of integers, I want to find which number is the closest to a number I give in input:

    &gt;&gt;&gt; myList = [4, 1, 88, 44, 3]
    &gt;&gt;&gt; myNumber = 5
    &gt;&gt;&gt; takeClosest(myList, myNumber)
    ...
    4

Is there any quick way to do this?

From list of integers, get number closest to a given value

I need to check if a value is an integer. I found this: https://stackoverflow.com/questions/4727569/how-to-check-whether-input-value-is-integer-or-float, but if I&#39;m not mistaken, the variable there is still of type `double` even though the ***value*** itself is indeed an `integer`.

How can I check if a value is of type Integer?

I have a pandas data frame with multiple columns and I would like to construct a dict from two columns: one as the dict&#39;s keys and the other as the dict&#39;s values. How can I do that?

Dataframe:

               area  count
    co tp
    DE Lake      10      7
    Forest       20      5
    FR Lake      30      2
    Forest       40      3

I need to define area as key, count as value in dict. Thank you in advance.

python pandas dataframe columns convert to dict key and value

How can I convert all numbers that are more than 3 digits down to a 4 digit or less number?

This is exactly what I mean:

    10345 = 10.3k
    10012 = 10k
    123546 = 123.5k
    4384324 = 4.3m

Rounding is not entirely important, but an added plus. 

I have looked into NSNumberFormatter but have not found the proper solution, and I have yet to find a proper solution here on SO. Any help is greatly appreciated, thanks! 

iOS convert large numbers to smaller format

In Python console:

    ~True

Gives me:

    -2

Why? Can someone explain this particular case to me in binary?



Why does ~True result in -2?

I&#39;d like to convert result table to JSON array in MySQL using preferably only plain MySQL commands. For example with query

    SELECT name, phone FROM person;

    | name | phone |
    | Jack | 12345 |
    | John | 23455 |

the expected JSON output would be

    [
      {
        &quot;name&quot;: &quot;Jack&quot;,
        &quot;phone&quot;: 12345
      },
      {
        &quot;name&quot;: &quot;John&quot;,
        &quot;phone&quot;: 23455
      }
    ]

Is there way to do that in plain MySQL?

EDIT:

There are some answers how to do this with e.g. [MySQL and PHP][1], but I couldn&#39;t find pure MySQL solution.


  [1]: https://stackoverflow.com/questions/383631/json-encode-mysql-results

Content Type	Original Author	Original Content on Stackoverflow
Question	mCY	View Question on Stackoverflow
Solution 1 - Ruby	Michael Kohl	View Answer on Stackoverflow
Solution 2 - Ruby	Yì Yáng	View Answer on Stackoverflow
Solution 3 - Ruby	Alexey Novikov	View Answer on Stackoverflow
Solution 4 - Ruby	Mahesh	View Answer on Stackoverflow
Solution 5 - Ruby	Arup Rakshit	View Answer on Stackoverflow
Solution 6 - Ruby	davidpm4	View Answer on Stackoverflow
Solution 7 - Ruby	Ajay Rathore	View Answer on Stackoverflow

Convert string with comma to integer

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How to group pandas DataFrame entries by date in a non-unique column

Why doesn't IList support AddRange

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