`is` checks that 2 arguments refer to the same object, `==` checks that 2 arguments have the same value.  `dir()` returns a `list` which contains the same data for both `foo` and `10`, but the actual `list` instances for the 2 things are different.

I have a small WPF application which used to compile just fine but is not anymore. I can&#39;t really say at which point it stopped building. It just worked fine one day, and the next it&#39;s not.

Here&#39;s the project structure:

![enter image description here][1]

There is no other projects or external references other than standard .net dlls.

Here&#39;s the user control where the problem originated:

    &lt;UserControl x:Class=&quot;TimeRecorder.HistoryUserControl&quot;
             xmlns=&quot;http://schemas.microsoft.com/winfx/2006/xaml/presentation&quot;
             xmlns:x=&quot;http://schemas.microsoft.com/winfx/2006/xaml&quot;
             xmlns:mc=&quot;http://schemas.openxmlformats.org/markup-compatibility/2006&quot; 
             xmlns:d=&quot;http://schemas.microsoft.com/expression/blend/2008&quot; 
             xmlns:local=&quot;clr-namespace:TimeRecorder.ViewModel&quot;
             xmlns:framework=&quot;clr-namespace:TimeRecorder.Framework&quot;
             mc:Ignorable=&quot;d&quot; Height=&quot;Auto&quot; Width=&quot;Auto&quot; Padding=&quot;5&quot;&gt;
    &lt;UserControl.Resources&gt;
        &lt;local:HistoryViewModel x:Key=&quot;ViewModel&quot;/&gt;
        &lt;framework:BoolToColorConverter x:Key=&quot;ColorConverter&quot;/&gt;
    &lt;/UserControl.Resources&gt;
    &lt;StackPanel DataContext=&quot;{StaticResource ViewModel}&quot;&gt;

And here&#39;s the error I get:
![http://i48.tinypic.com/5u1u8w.png][2]

**Please note that this is not just the one file in the screenshot, but all references I add in similar fashion in xaml in all user control/window files in this project.**

So the file is there, the namespace in the file is correct, the namespace/class name in the xaml file is (to my understanding) correct. I get intellisense when I type in the xaml so it finds the files ok then but not when it compiles.

The most common solution for this in other posts has been the .net framework version. It is currently set to .Net Framework 4 for both my main and test project. The full version not the client profile.

**Here&#39;s what I think I messed up:**
In the configuration manager, both  projects have their Platform set to Any CPU, but at one point when trying to solve this I noticed that the main project was set to x86 and the test project was set to Any CPU. So I added Any CPU manually for the main project in the configuration manager. However I honestly don&#39;t know if I did this correctly or even if I should do it. So as an additional question, is there a way I can reset the configuration manager to its default state? Will this have anything to say for the main problem? I don&#39;t know if the main project was always set to x86 or not or if I somehow changed it to x86 and then it broke. As mentioned this project was compiling just fine for a while. 

  [1]: http://i.stack.imgur.com/wDvfJ.png
  [2]: http://i.stack.imgur.com/fAsA0.png

the name &lt;...&gt; does not exist in the namespace clr-namespace &lt;...&gt;

For the moment when I want to show a single post without using a loop I use this:

    &lt;?php
    $post_id = 54;
    $queried_post = get_post($post_id);
    echo $queried_post-&gt;post_title; ?&gt;

The problem is that when I move the site, the id&#39;s usually change.
Is there a way to query this post by slug?
    

WordPress query single post by slug

I run the following in the Python interpreter:

&lt;!-- language: lang-python --&gt;

    &gt;&gt;&gt; foo = 10
    &gt;&gt;&gt; dir(foo) == dir(10)
    True
    &gt;&gt;&gt; dir(foo) is dir(10)
    False
    &gt;&gt;&gt; 

Why is this?

double equals vs is in python

I run the following in the Python interpreter:

<pre><code class="hljs language-python-repl">>>> foo = 10
>>> dir(foo) == dir(10)
True
>>> dir(foo) is dir(10)
False
>>> 
</code></pre>
Why is this?

I would like to use argparse to parse boolean command-line arguments written as &quot;--foo True&quot; or &quot;--foo False&quot;. For example:

    my_program --my_boolean_flag False

However, the following test code does not do what I would like:

    import argparse
    parser = argparse.ArgumentParser(description=&quot;My parser&quot;)
    parser.add_argument(&quot;--my_bool&quot;, type=bool)
    cmd_line = [&quot;--my_bool&quot;, &quot;False&quot;]
    parsed_args = parser.parse(cmd_line)

Sadly, `parsed_args.my_bool` evaluates to `True`. This is the case even when I change `cmd_line` to be `[&quot;--my_bool&quot;, &quot;&quot;]`, which is surprising, since `bool(&quot;&quot;)` evalutates to `False`.

How can I get argparse to parse `&quot;False&quot;`, `&quot;F&quot;`, and their lower-case variants to be `False`?


Parsing boolean values with argparse

Is there a built-in way to use `read_csv` to read only the first `n` lines of a file without knowing the length of the lines ahead of time? I have a large file that takes a long time to read, and occasionally only want to use the first, say, 20 lines to get a sample of it (and prefer not to load the full thing and take the head of it).

If I knew the total number of lines I could do something like `footer_lines = total_lines - n` and pass this to the `skipfooter` keyword arg. My current solution is to manually grab the first `n` lines with python and StringIO it to pandas:

    import pandas as pd
    from StringIO import StringIO

    n = 20
    with open(&#39;big_file.csv&#39;, &#39;r&#39;) as f:
        head = &#39;&#39;.join(f.readlines(n))

    df = pd.read_csv(StringIO(head))

It&#39;s not that bad, but is there a more concise, &#39;pandasic&#39; (?) way to do it with keywords or something?

Way to read first few lines for pandas dataframe

When importing modules in Python, what is the difference between this:

    from module import a, b, c, d

and this

    from module import a
    from module import b
    from module import c
    from module import d

To me it makes sense always to condense code and use the first example, but I&#39;ve been seeing some code samples out there dong the second. Is there any difference at all or is it all in the preference of the programmer?

Python Module Import: Single-line vs Multi-line

What&#39;s the recommended Python idiom for splitting a string on the *last* occurrence of the delimiter in the string? example:

    # instead of regular split
    &gt;&gt; s = &quot;a,b,c,d&quot;
    &gt;&gt; s.split(&quot;,&quot;)
    &gt;&gt; [&#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;d&#39;]
    
    # ..split only on last occurrence of &#39;,&#39; in string:
    &gt;&gt;&gt; s.mysplit(s, -1)
    &gt;&gt;&gt; [&#39;a,b,c&#39;, &#39;d&#39;]

`mysplit` takes a second argument that is the occurrence of the delimiter to be split. Like in regular list indexing, `-1` means the last from the end. How can this be done?

Splitting on last delimiter in Python string?

My question is simple: I have a python script that generates figures using matplotlib. Every time i run it it generates new windows with figures. How can I have the script close windows that were opened the previous time it ran?

the analogous command in matlab is to put &#39;close all&#39; at the beginning of your matlab script.

I have seen several suggestions to do something like

    import matplotlib.pyplot as plt
    plt.close(&quot;all&quot;)

This solution works if you run your script from the python shell, eg using

    &gt;&gt;&gt;&gt; execfile(&quot;myScript.py&quot;)

However, I have found that this doesn&#39;t work if I run the script using Eclipse / PyDev. How can I get it to work in Eclipse?



example:

    from numpy import *
    from matplotlib.pyplot import *
    from scipy import *

    close(&quot;all&quot;) 
        #close any previously open plots - this doesn&#39;t work when running via Eclipse

    t = linspace(0, 0.1,1000)
    w = 60*2*pi

    figure()
    plot(t,cos(w*t))
    plot(t,cos(w*t-2*pi/3))
    plot(t,cos(w*t-4*pi/3))
    show()

This should plot the ideal waveforms for a nice 3-phase power supply.

Close pre-existing figures in matplotlib when running from eclipse

I&#39;m trying to make a function that will compare multiple variables to an integer and output a string of three letters. I was wondering if there was a way to translate this into Python. So say:

    x = 0
    y = 1
    z = 3
    mylist = []

    if x or y or z == 0 :
    	mylist.append(&quot;c&quot;)
    if x or y or z == 1 :
        mylist.append(&quot;d&quot;)
    if x or y or z == 2 :
        mylist.append(&quot;e&quot;)
    if x or y or z == 3 : 
        mylist.append(&quot;f&quot;)

which would return a list of:

    [&quot;c&quot;, &quot;d&quot;, &quot;f&quot;]

Is something like this possible?
    
    

How to test multiple variables for equality against a single value?

I am trying to compare the current date and time with dates and times specified in models using comparison operators:

    if challenge.datetime_start &lt;= datetime.now() &lt;= challenge.datetime_end:

The script errors out with: 

    TypeError: can&#39;t compare offset-naive and offset-aware datetimes

The models look like this:

    class Fundraising_Challenge(models.Model):
    	name = models.CharField(max_length=100)
    	datetime_start = models.DateTimeField()
    	datetime_end = models.DateTimeField()

I also have django using locale date and times.

What I haven&#39;t been able to find is the format django uses for DateTimeField().  Is it naive or aware?  And how do I get datetime.now() to recognize locale datetime?


Can&#39;t compare naive and aware datetime.now() &lt;= challenge.datetime_end

PHP is famous for its type-juggling. I must admit it puzzles me, and I&#39;m having a hard time to find out basic logical/fundamental things in comparisons.

For example: If `$a &gt; $b` is true and `$b &gt; $c` is true, must it mean that `$a &gt; $c` is *always* true too?

Following basic logic, I would say *yes* however I&#39;m that puzzled I do not really trust PHP in this. Maybe someone can provide an example where this is not the case?

Also I&#39;m wondering with the strict lesser-than and strict greater-than operators (as their meaning is described as strictly which I only knew in the past from the equality comparisons) if it makes any difference if left and right operands are swapped with strictly unequal values:

    # Precondition:
    if ($a === $b) {
        throw new Exception(
           &#39;Both are strictly equal - can not compare strictly for greater or smaller&#39;
        );
    }

    ($a &gt; $b) !== ($b &gt; $a)

For most of all type comparison combinations these [greater / lesser comparison operators](http://php.net/language.operators.comparison) are not documented, so reading the manual was not really helpful in this case.


Type-juggling and (strict) greater/lesser-than comparisons in PHP

Hi below is my compare method of my comparator. I am not sure what is wrong. I looked up other similar titled questions and answers on stack overflow but not sure what is wrong with my method but I keep getting java.lang.IllegalArgumentException: Comparison method violates its general contract!

Any help will be greatly appreciated

    public int compare(Node o1, Node o2)
    {
        HashMap&lt;Integer,Integer&gt; childMap = orderMap.get(parentID);
        if(childMap != null &amp;&amp; childMap.containsKey(o1.getID()) &amp;&amp; 
                               childMap.containsKey(o2.getID()))
        {
            int order1 = childMap.get(o1.getID());
            int order2 = childMap.get(o2.getID());

            if(order1&lt;order2) 
                return -1;
            else if(order1&gt;order2) 
                return 1;
            else 
                return 0;
        }
        else
            return 0;
    }

 Adding the exception I am getting

    java.lang.IllegalArgumentException: Comparison method violates its general contract!
	at java.util.TimSort.mergeLo(TimSort.java:747)
	at java.util.TimSort.mergeAt(TimSort.java:483)
	at java.util.TimSort.mergeCollapse(TimSort.java:410)
	at java.util.TimSort.sort(TimSort.java:214)
	at java.util.TimSort.sort(TimSort.java:173)
	at java.util.Arrays.sort(Arrays.java:659)
	at java.util.Collections.sort(Collections.java:217)

java.lang.IllegalArgumentException: Comparison method violates its general contract

I&#39;ve received this quiz on an online form to apply for a recent Java event in my city:

    //Instead of this comment what code should be written so you can get &quot;Gotcha!&quot; printed
    if( a == a ){
      System.out.println(&quot;Not yet...&quot;);
    } else {
      System.out.println(&quot;Gotcha!&quot;);
    }

*AFAIK: the `==` comparison in Java on objects checks if both objects are the same in memory, and overwriting the `equals` method doesn&#39;t overwrite the `==` operator like C++ and other languages that allow operator overloading*

I tried to change `a` value with the following features in Java and none of them got me what I wanted:

 1. transient variable
 2. target annotation
 3. garbage collector
 4. mutable objects

What should I do to get the `a` object to be different from itself?

How can a Java variable be different from itself?

The input `int` value only consist out of 1 or 0.
I can solve the problem by writing a `if else` statement.

Isn&#39;t there a way to cast the `int` into a `boolean`?

Better way to convert an int to a boolean

Setting default optional values in JavaScript is usually done via the `||` character

    var Car = function(color) {
      this.color = color || &#39;blue&#39;;
    };

    var myCar = new Car();
    console.log(myCar.color); // &#39;blue&#39;

    var myOtherCar = new Car(&#39;yellow&#39;);
    console.log(myOtherCar.color); // &#39;yellow&#39;

That works because `color` is `undefined` and `undefined || String` is always the `String`. Of course that also works the other way around `String || undefined` is `String`. When two `Strings` are present the first one wins `&#39;this&#39; || &#39;that&#39;` is `&#39;this&#39;`. It does NOT work the other way around as `&#39;that&#39; || &#39;this&#39;` is `&#39;that&#39;`.

The question is: How can I achieve the same with boolean values?

Take the following example

    var Car = function(hasWheels) {
      this.hasWheels = hasWheels || true;
    }

    var myCar = new Car();
    console.log(myCar.hasWheels); // true

    var myOtherCar = new Car(false)
    console.log(myOtherCar.hasWheels); // ALSO true !!!!!!

For `myCar` it works because `undefined || true` is `true` but as you can see it does NOT work for `myOtherCar` because `false || true` is `true`. Changing the order doesn&#39;t help as `true || false` is still `true`.

Therefore, am I missing something here or is the following the only way to set the default value?

    this.hasWheels = (hasWheels === false) ? false: true

Cheers!

How to set default boolean values in JavaScript?

How do you check if a boolean is null or not? So if I know &quot;hideInNav&quot; is null. How do I stop 
it from further executing? Something like the below doesn&#39;t seem to work but why? 

    boolean hideInNav = parent.getProperties().get(&quot;hideInNav&quot;, false);
    String hideNavigation = hideInNav != null ? hideInNav : &quot;&quot;;



Java check if boolean is null

I print a `bool` to an output stream like this:

    #include &lt;iostream&gt;

    int main()
    {
        std::cout &lt;&lt; false &lt;&lt; std::endl;
    }

Does the standard require a specific result on the stream (e.g. `0` for `false`)?

C++ printing boolean, what is displayed?

In the case of using enums, is it better to use:

    if (enumInstance.Equals(MyEnum.SomeValue))

or to use

    if (enumInstance == MyEnum.SomeValue)

Are their any important considerations using one vs the other?

c# enum equals() vs ==

I am practicing for an exam, and found a sample problem that I don&#39;t understand. 

For the following code, find what the output is: 

    public class Test {

        private static int count = 0;

        public boolean equals(Test testje) {
            System.out.println(&quot;count = &quot; + count);
            return false;
        }

        public static void main(String [] args) {
            Object t1 = new Test();
            Object t2 = new Test();
            Test t3 = new Test();
            Object o1 = new Object();

            ++count; t1.equals(t2);
            ++count; t1.equals(t3);
            ++count; t3.equals(o1);
            ++count; t3.equals(t3);
            ++count; t3.equals(t2);
        }
    }

The output of this code is `count = 4`, but I don&#39;t understand why. Can anyone help me?

Java code related to equals method

Given some arrays in Kotlin

&lt;!-- language: lang-kotlin --&gt;

    let a = arrayOf(&quot;first&quot;, &quot;second&quot;)
    val b = arrayOf(&quot;first&quot;, &quot;second&quot;)
    val c = arrayOf(&quot;1st&quot;, &quot;2nd&quot;)

Are there built-in functions to the Kotlin std-lib that tests two arrays for (value) equality for each element?

Thus resulting in:

&lt;!-- language: lang-kotlin --&gt;

    a.equals(b) // true
    a.equals(c) // false

`equals()` is actually returning `false` in both cases, but maybe there are built-in functions to Kotlin that one could use?

There is the static function `java.utils.Arrays.deepEquals(a.toTypedArray(), b.toTypedArray())` but I would rather prefer an instance method as it would work better with optionals.


How to compare two arrays in Kotlin?

I have two lists of arrays. 

How do I easily compare equality of these *with Java 8 and its features*, without using external libraries? I am looking for a &quot;better&quot; (higher-level, shorter, more efficient) solution than brute-force code like this (untested code, may contain typos etc, not the point of the question):

    boolean compare(List&lt;String[]&gt; list1, List&lt;String[]&gt; list2) 
    {
        // tests for nulls etc omitted
        if(list1.size() != list2.size()) {
           return false;
        }
        for(i=0; i&lt;list1.size(); ++i) {
            if(!Arrays.equals(list1.get(i), list2.get(i))) {
                return false;
            }
        }
        return true;
    }

Or, if there isn&#39;t any nicer way, that&#39;s a valid answer too.

Bonus: If Java 9 offers an even better way what whaterver Java 8 can offer, feel free to mention it as well.

**Edit:** After looking at the comments, and seeing how this question has become moderately hot, I think **the &quot;*better*&quot; should include first checking lengths of all arrays, before checking array contents**, because that has potential to find inequality much quicker, if inner arrays are long.

How to compare equality of lists of arrays with modern Java?

I have the following data class

    data class PuzzleBoard(val board: IntArray) {
        val dimension by lazy { Math.sqrt(board.size.toDouble()).toInt() }
    }

I read that data classes in Kotlin get `equals()`/`hashcode()` method for free.

I instantiated two objects.

    val board1 = PuzzleBoard(intArrayOf(1,2,3,4,5,6,7,8,0))
    val board2 = PuzzleBoard(intArrayOf(1,2,3,4,5,6,7,8,0))

But still, the following statements return false.

    board1 == board2
    board1.equals(board2)

Equals method for data class in Kotlin

My question is **not** about floating precision. It is about why `Equals()` is different from `==`.

I understand why `.1f + .2f == .3f` is `false` (while `.1m + .2m == .3m` is `true`).  
I get that `==` is reference and `.Equals()` is value comparison. (_Edit_: I know there is more to this.)

But why is `(.1f + .2f).Equals(.3f)` `true`, while `(.1d+.2d).Equals(.3d)` is still `false`?

     .1f + .2f == .3f;              // false
    (.1f + .2f).Equals(.3f);        // true
    (.1d + .2d).Equals(.3d);        // false

(.1f+.2f==.3f) != (.1f+.2f).Equals(.3f) Why?

I am trying to compare two structs using equals (==) in C#. My struct is below:

    public struct CisSettings : IEquatable&lt;CisSettings&gt;
    {
        public int Gain { get; private set; }
        public int Offset { get; private set; }
        public int Bright { get; private set; }
        public int Contrast { get; private set; }
    
        public CisSettings(int gain, int offset, int bright, int contrast) : this()
        {
            Gain = gain;
            Offset = offset;
            Bright = bright;
            Contrast = contrast;
        }
    
        public bool Equals(CisSettings other)
        {
            return Equals(other, this);
        }
    
        public override bool Equals(object obj)
        {
            if (obj == null || GetType() != obj.GetType())
            {
                return false;
            }
    
            var objectToCompareWith = (CisSettings) obj;
    
            return objectToCompareWith.Bright == Bright &amp;&amp; objectToCompareWith.Contrast == Contrast &amp;&amp;
                   objectToCompareWith.Gain == Gain &amp;&amp; objectToCompareWith.Offset == Offset;
            
        }
    
        public override int GetHashCode()
        {
            var calculation = Gain + Offset + Bright + Contrast;
            return calculation.GetHashCode();
        }
    }

I am trying to have struct as a property in my class, and want to check to see if the struct is equal to the value I am trying to assign it to, before I go ahead and do so, so I am not indicating the property has changed when it hasn&#39;t, like so:

    public CisSettings TopCisSettings
    {
        get { return _topCisSettings; }
        set
        {
            if (_topCisSettings == value)
            {
                return;
            }
            _topCisSettings = value;
            OnPropertyChanged(&quot;TopCisSettings&quot;);
        }
    }

However, on the line where I check for equality, I get this error:

&gt; Operator &#39;==&#39; cannot be applied to operands of type &#39;CisSettings&#39; and
&gt; &#39;CisSettings&#39;

I can&#39;t figure out why this is happening, could somebody point me in the right direction?

Comparing two structs using ==

I wonder what the difference is between those operations in Scheme. I have seen similar questions in Stack Overflow but they are about Lisp, and there is not a comparison between three of those operators.

I am writing the different types of commands in Scheme, and I get the following outputs:

    (eq? 5 5) --&gt;#t
    (eq? 2.5 2.5) --&gt;#f
    (equal? 2.5 2.5) --&gt; #t
    (= 2.5 2.5) --&gt; #t

Why is this the case?

What is the difference between eq?, eqv?, equal?, and = in Scheme?

First example:

    int main(){
        using namespace std;   
        vector&lt;int&gt; v1{10, 20, 30, 40, 50};
        vector&lt;int&gt; v2{10, 20, 30, 40, 50};
     
        if(v1==v2)
            cout&lt;&lt;&quot;equal&quot;;
        else
            cout&lt;&lt;&quot;unequal&quot;;
    }   // it returns equal 

Second example:

    int main(){
        using namespace std;   
        vector&lt;int&gt; v1{10, 20, 30, 40, 50};
        vector&lt;int&gt; v2{10, 20, 100000, 40, 50};
         
        if(v1==v2)
            cout&lt;&lt;&quot;equal&quot;;
        else
            cout&lt;&lt;&quot;unequal&quot;;
    }   // it returns notequal 



Can I use &#39; == &#39; to compare two vectors. I tried it and seems to be working fine. But I don&#39;t know whether it will work in more complex situations

Say we have 5 string arrays as such:
    
    string[] a = {&quot;The&quot;,&quot;Big&quot;, &quot;Ant&quot;};
    string[] b = {&quot;Big&quot;,&quot;Ant&quot;,&quot;Ran&quot;};
    string[] c = {&quot;The&quot;,&quot;Big&quot;,&quot;Ant&quot;};
    string[] d = {&quot;No&quot;,&quot;Ants&quot;,&quot;Here&quot;};
    string[] e = {&quot;The&quot;, &quot;Big&quot;, &quot;Ant&quot;, &quot;Ran&quot;, &quot;Too&quot;, &quot;Far&quot;};

Is there a method to compare these strings to each other without looping through them in C# such that only a and c would yield the boolean true? In other words, all elements must be equal and the array must be the same size? Again, without using a loop if possible.


Content Type	Original Author	Original Content on Stackoverflow
Question	ben	View Question on Stackoverflow
Solution 1 - Python	Silas Ray	View Answer on Stackoverflow

double equals vs is in python

Python Problem Overview

Python Solutions

Solution 1 - Python

WordPress query single post by slug

the name <...> does not exist in the namespace clr-namespace <...>

Attributions