Because the inequality operator in VBA is `&lt;&gt;`

    If strTest &lt;&gt; &quot;&quot; Then
        .....


the operator `!=` is used in C#, C++.

In VBA, the `!=` operator is the `Not` operator, like this:

    If Not strTest = &quot;&quot; Then ...

Just a note. If you want to compare a string with  `&quot;&quot;` ,in your case,  use 

    If LEN(str) &gt; 0 Then

or even just

    If LEN(str) Then
instead. 



We are developing a highly performance critical software in C++. There we need a concurrent hash map and implemented one. So we wrote a benchmark to figure out, how much slower our concurrent hash map is compared with `std::unordered_map`.

But, `std::unordered_map` seems to be incredibly slow... So this is our micro-benchmark (for the concurrent map we spawned a new thread to make sure that locking does not get optimized away and note that I never inser 0 because I also benchmark with `google::dense_hash_map`, which needs a null value):

    boost::random::mt19937 rng;
    boost::random::uniform_int_distribution&lt;&gt; dist(std::numeric_limits&lt;uint64_t&gt;::min(), std::numeric_limits&lt;uint64_t&gt;::max());
    std::vector&lt;uint64_t&gt; vec(SIZE);
    for (int i = 0; i &lt; SIZE; ++i) {
        uint64_t val = 0;
        while (val == 0) {
            val = dist(rng);
        }
        vec[i] = val;
    }
    std::unordered_map&lt;int, long double&gt; map;
    auto begin = std::chrono::high_resolution_clock::now();
    for (int i = 0; i &lt; SIZE; ++i) {
        map[vec[i]] = 0.0;
    }
    auto end = std::chrono::high_resolution_clock::now();
    auto elapsed = std::chrono::duration_cast&lt;std::chrono::milliseconds&gt;(end - begin);
    std::cout &lt;&lt; &quot;inserts: &quot; &lt;&lt; elapsed.count() &lt;&lt; std::endl;
    std::random_shuffle(vec.begin(), vec.end());
    begin = std::chrono::high_resolution_clock::now();
    long double val;
    for (int i = 0; i &lt; SIZE; ++i) {
        val = map[vec[i]];
    }
    end = std::chrono::high_resolution_clock::now();
    elapsed = std::chrono::duration_cast&lt;std::chrono::milliseconds&gt;(end - begin);
    std::cout &lt;&lt; &quot;get: &quot; &lt;&lt; elapsed.count() &lt;&lt; std::endl;


(EDIT: the whole source code can be found here: http://pastebin.com/vPqf7eya)

The result for `std::unordered_map` is:

    inserts: 35126
    get    : 2959

For `google::dense_map`:

    inserts: 3653
    get    : 816

For our hand backed concurrent map (which does locking, although the benchmark is single threaded - but in a separate spawn thread):

    inserts: 5213
    get    : 2594

If I compile the benchmark program without pthread support and run everything in the main thread, I get the following results for our hand backed concurrent map:

    inserts: 4441
    get    : 1180

I compile with the following command:

    g++-4.7 -O3 -DNDEBUG -I/tmp/benchmap/sparsehash-2.0.2/src/ -std=c++11 -pthread main.cc

So especially inserts on `std::unordered_map` seem to be extremely expensive - 35 seconds vs 3-5 seconds for other maps. Also the lookup time seems to be quite high.

My question: why is this? I read another question on stackoverflow where someone asks, why `std::tr1::unordered_map` is slower than his own implementation. There the highest rated answer states, that the `std::tr1::unordered_map` needs to implement a more complicated interface. But I can not see this argument: we use a bucket approach in our concurrent_map, `std::unordered_map` uses a bucket-approach too (`google::dense_hash_map` does not, but than `std::unordered_map` should be at least as fast than our hand backed concurrency-safe version?). Apart from that I can not see anything in the interface that force a feature which makes the hash map perform badly...

So my question: is it true that `std::unordered_map` seems to be very slow? If no: what is wrong? If yes: what is the reason for that.

And my main question: why is inserting a value into a `std::unordered_map` so terrible expensive (even if we reserve enough space at the beginning, it does not perform much better - so rehashing seems not to be the problem)?

EDIT:
=====

First of all: yes the presented benchmark is not flawless - this is because we played around a lot with it and it is just a hack (for example the `uint64` distribution to generate ints would in practice not be a good idea, exclude 0 in a loop is kind of stupid etc...).

At the moment most comments explain, that I can make the unordered_map faster by preallocating enough space for it. In our application this is just not possible: we are developing a database management system and need a hash map to store some data during a transaction (for example locking information). So this map can be everything from 1 (user just makes one insert and commits) to billions of entries (if full table scans happen). It is just impossible to preallocate enough space here (and just allocate a lot in the beginning will consume too much memory).

Furthermore, I apologize, that I did not state my question clear enough: I am not really interested in making unordered_map fast (using googles dense hash map works fine for us), I just don&#39;t really understand where this huge performance differences come from. It can not be just preallocation (even with enough preallocated memory, the dense map is an order of magnitude faster than unordered_map, our hand backed concurrent map starts with an array of size 64 - so a smaller one than unordered_map).

So what is the reason for this bad performance of `std::unordered_map`? Or differently asked: Could one write an implementation of the `std::unordered_map` interface which is standard conform and (nearly) as fast as googles dense hash map? Or is there something in the standard that enforces the implementer to chose an inefficient way to implement it?

EDIT 2:
=====
By profiling I see that a lot of time is used for integer divions. `std::unordered_map` uses prime numbers for the array size, while the other implementations use powers of two. Why does `std::unordered_map` use prime-numbers? To perform better if the hash is bad? For good hashes it does imho make no difference.

EDIT 3:
=====
These are the numbers for `std::map`:

    inserts: 16462
    get    : 16978

Sooooooo: why are inserts into a `std::map` faster than inserts into a `std::unordered_map`... I mean WAT? `std::map` has a worse locality (tree vs array), needs to make more allocations (per insert vs per rehash + plus ~1 for each collision) and, most important: has another algorithmic complexity (O(logn) vs O(1))!

Is gcc std::unordered_map implementation slow? If so - why?

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

The problem is that `!=` does not work as a function in excel vba.

I want to be able to use 

`If strTest != &quot;&quot; Then` instead of `If strTest = &quot;&quot; Then`

Is there another approach to do this besides `!=`?


My function to mimic `!=` is 


    Sub test()
    
    Dim intTest As Integer
    Dim strTest As String
    
    intTest = 5
    
    strTest = CStr(intTest) &#39; convert
    
    Range(&quot;A&quot; + strTest) = &quot;5&quot;
    
    
    
        For i = 1 To 10
            Cells(i, 1) = i
            
            If strTest = &quot;&quot; Then
                Cells(i, 1) = i
            End If
    
        Next i
    
    
    End Sub







What is the equivalent of &quot;!=&quot; in Excel VBA?

The problem is that <code>!=</code> does not work as a function in excel vba.
I want to be able to use
<code>If strTest != "" Then</code> instead of <code>If strTest = "" Then</code>
Is there another approach to do this besides <code>!=</code>?
My function to mimic <code>!=</code> is
<pre><code class="hljs language-vbnet">Sub test()

Dim intTest As Integer
Dim strTest As String

intTest = 5

strTest = CStr(intTest) ' convert

Range("A" + strTest) = "5"



 For i = 1 To 10
 Cells(i, 1) = i
 
 If strTest = "" Then
 Cells(i, 1) = i
 End If

 Next i


End Sub
</code></pre>

I have a list of dates, each date in it can occur more than once. I want to count the number of times each date occurs (histogram) and display it in a graph (with the Y axis being the number of times the date occurs and the X axis being the date itself)?

Sample list:

    19/05/2012
    19/05/2012
    19/05/2012
    17/05/2012
    17/05/2012
    16/05/2012
    16/05/2012
    16/05/2012
    16/05/2012
    15/05/2012
    15/05/2012
    15/05/2012
    15/05/2012
    12/05/2012
    12/05/2012
    12/05/2012
    7/05/2012

I clicked every menu option over the past few years and never did I find anything specific to this. Would this be a case for using PivotTables somehow?

Count number of times a date occurs and make a graph out of it

This seems like a simple Pivot Table to learn with.  I would like to do a count of unique values for a particular value I&#39;m grouping on.

For instance, I have this:

    ABC   123
    ABC   123
    ABC   123
    DEF   456
    DEF   567
    DEF   456
    DEF   456

What I want is a pivot table that shows me this:

    ABC   1
    DEF   2

The simple pivot table that I create just gives me this (a count of how many rows):

    ABC   3
    DEF   4  

But I want the number of unique values instead.

What I&#39;m really trying to do is find out which values in the first column don&#39;t have the same value in the second column for all rows.  In other words, &quot;ABC&quot; is &quot;good&quot;, &quot;DEF&quot; is &quot;bad&quot;

I&#39;m sure there is an easier way to do it but thought I&#39;d give pivot table a try...

Simple Pivot Table to Count Unique Values

I&#39;ve found this method for finding the last data containing row in a sheet:

    ws.Range(&quot;A65536&quot;).End(xlUp).row

Is there a similar method for finding the last data containing column in a sheet?

How do I find the last column with data?

I am using a While...Wend loop of VBA.

    Dim count as Integer
    
    While True
        count=count+1

        If count = 10 Then
            &#39;&#39;What should be the statement to break the While...Wend loop? 
            &#39;&#39;Break or Exit While not working
        EndIf
    Wend

I don&#39;t want to use condition like `While count&lt;=10...Wend

Break out of a While...Wend loop

I&#39;m currently using pandas to read an Excel file and present its sheet names to the user, so he can select which sheet he would like to use. The problem is that the files are really big (70 columns x 65k rows), taking up to 14s to load on a notebook (the same data in a CSV file is taking 3s).

My code in panda goes like this:

    xls = pandas.ExcelFile(path)
    sheets = xls.sheet_names

I tried xlrd before, but obtained similar results. This was my code with xlrd:

    xls = xlrd.open_workbook(path)
    sheets = xls.sheet_names

So, can anybody suggest a faster way to retrieve the sheet names from an Excel file than reading the whole file?

How to obtain sheet names from XLS files without loading the whole file?

We are writing an MS Outlook plugin. To satisfy our business-logic, it should check all appointments between some dates. We are experiencing several problems with retrieving all items from calendars. We tried two options:

1. Outlook API. We use the standard logic that is described in MSDN - sort items by [Start], set `IncludeRecurrences` to `True` and run the Find\Restrict query over calendar items [like here](http://msdn.microsoft.com/en-us/library/office/aa220093(v=office.11).aspx). It works fine in our test environment. However, in our customer&#39;s environment: For recurring appointments, start and end dates are set to the corresponding dates of a &#39;master appointment.&#39; For example, in some room&#39;s calendar we have a weekly appointment that was created in January, and if we try to find all items in August, we get among others four items of this recurring appointment, but their start and end dates are set to January. But Outlook displays correct dates in the same calendar...

2. Very bad, but we still have WebDAV! We write a simple test application and try to query all items from the calendar using WebDAV. Of course, we didn&#39;t reinvent the wheel and just pasted the code from [documentation](http://msdn.microsoft.com/en-us/library/exchange/aa123570(v=exchg.65).aspx). The previous problem is solved, but the next one arises: It doesn&#39;t return recurring items that were created more than approximately six months ago. I Haven&#39;t a clue - there are no parameters restricting &#39;old&#39; items! 

What is wrong? Are we missing something important? 

Technical details: Exchange 2003, Outlook 2003-2010. Frankly speaking, the first error disappears if we turn on Cached Exchange Mode, but we can&#39;t do that.

&lt;!-- language: c# --&gt;

    var nameSpace = application.GetNamespace(&quot;MAPI&quot;);
    var recepient = nameSpace.CreateRecipient(roomEMail);
    recepient.Resolve();
    var calendar = nameSpace.GetSharedDefaultFolder(recepient, OlDefaultFolders.olFolderCalendar);
    var filter = string.Format(&quot;[Start]&lt;&#39;{1}&#39; AND [End]&gt;&#39;{0}&#39;&quot;,
      dateFrom.ToString(&quot;dd/MM/yyyy HH:mm&quot;, CultureInfo.InvariantCulture), dateTo.ToString(&quot;dd/MM/yyyy HH:mm&quot;, CultureInfo.InvariantCulture)
    );
    var allItems = calendar.Items;
    allItems.Sort(&quot;[Start]&quot;);
    allItems.IncludeRecurrences = true;
    var _item = allItems.Find(filter);
    while (_item != null) {
      AppointmentItem item = _item as AppointmentItem;
      if (item != null) {
        if (item.Subject != &quot;some const&quot;)
          &amp;&amp; (item.ResponseStatus != OlResponseStatus.olResponseDeclined)
          &amp;&amp; (item.MeetingStatus != OlMeetingStatus.olMeetingReceivedAndCanceled 
          &amp;&amp; item.MeetingStatus != OlMeetingStatus.olMeetingCanceled))
        {
          /* Here we copy item to our internal class.
           * We need: Subject, Start, End, Organizer, Recipients, MeetingStatus,
           * AllDayEvent, IsRecurring, RecurrentState, ResponseStatus,
           * GlobalAppointmentID */
        }
      }
      _item = allItems.FindNext();
    }

##UPDATE 1:
Additional research using OutlookSpy shows that the problem is not in our code - the Start\End dates are incorrect inside the API when Cached Exchange Mode is off. But Outlook developers were aware of it, and they somehow display correct dates in calendars! Does anyone know how?

### UPDATE 2: 
Answer from Outlook Support Escalation Engineer: 
&gt; Based on this, I can confirm that this is a problem in our product.

Retrieve calendar items (Outlook API, WebDAV) displaying strange behaviour

Does anyone have an Excel VBA function which can return the column letter(s) from a number?

For example, entering *100* should return `CV`.

Function to convert column number to letter?

In the VBA editor of Office (&lt;kbd&gt;ALT&lt;/kbd&gt; + &lt;kbd&gt;F11&lt;/kbd&gt;), how do you comment or uncomment a block of code?

How to comment and uncomment blocks of code in the Office VBA Editor

In python I can do this:

&lt;!-- language: lang-py --&gt;

    def f((a, b)):
        return a + b

    d = (1, 2)
    f(d)

Here the passed in tuple is being decomposed while its being passed to `f`.

Right now in scala I am doing this:

&lt;!-- language: lang-scala --&gt;

    def f(ab: (Int, Int)): Int = {
        val (a, b) = ab
        a + b
    }

    val d = (1, 2)
    f(d)

Is there something I can do here so that the decomposition happens while the arguments are passed in? Just curious.


Decomposing tuples in function arguments

I&#39;ve been trying Vim for any text editing work for almost a week now. I want to know the fastest way to select a C function definition.

For example, if I have a function like this:

```c
void helloworlds( int num )
{
    int n;
    for ( n = 0; n &lt; num; ++n ) {
        printf( &quot;Hello World!\n&quot; );
    }
}
```

How would I be able to delete the whole definition including the function name?

Selecting entire function definition in Vim

I find the named parameters feature in C# quite useful in some cases.

    calculateBMI(70, height: 175);

What can I use if I want this in JavaScript? 

---

What I don’t want is this:

    myFunction({ param1: 70, param2: 175 });

    function myFunction(params){
      // Check if params is an object
      // Check if the parameters I need are non-null
      // Blah blah
    }

That approach I’ve already used. Is there another way?

I’m okay using any library to do this.

Is there a way to provide named parameters in a function call in JavaScript?

In JavaScript, How can I call a function after a specific time interval?

Here is my function I want to run:

    function FetchData() {
    }

Javascript: Call a function after specific time period

I&#39;m asking this question because of a discussion on the comment thread of [this answer][1]. I&#39;m 90% of the way to getting my head round it.

    In [1]: class A(object):  # class named &#39;A&#39;
       ...:     def f1(self): pass
       ...:
    In [2]: a = A()  # an instance

`f1` exists in three different forms:

    In [3]: a.f1  # a bound method
    Out[3]: &lt;bound method a.f1 of &lt;__main__.A object at 0x039BE870&gt;&gt;
    In [4]: A.f1  # an unbound method
    Out[4]: &lt;unbound method A.f1&gt;
    In [5]: a.__dict__[&#39;f1&#39;]  # doesn&#39;t exist
    KeyError: &#39;f1&#39;
    In [6]: A.__dict__[&#39;f1&#39;]  # a function
    Out[6]: &lt;function __main__.f1&gt;

What is the difference between the _bound method_, _unbound method_ and _function_ objects, all of which are described by f1? How does one call these three objects? How can they be transformed into each other? The [documentation][2] on this stuff is quite hard to understand.


  [1]: https://stackoverflow.com/a/11934332/1523776
  [2]: http://docs.python.org/reference/datamodel.html#invoking-descriptors

What is the difference between a function, an unbound method and a bound method?

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?

    struct X
    {
        X()    { std::cout &lt;&lt; &quot;X()\n&quot;;    }
        X(int) { std::cout &lt;&lt; &quot;X(int)\n&quot;; }
    };
    
    const int answer = 42;
    
    int main()
    {
        X(answer);
    }

I would have expected this to print either

- `X(int)`, because `X(answer);` could be interpreted as a cast from `int` to `X`, or
- nothing at all, because `X(answer);` could be interpreted as the declaration of a variable.

However, [it prints `X()`](http://ideone.com/QZDO1), and I have no idea why `X(answer);` would call the default constructor.

BONUS POINTS: What would I have to change to get a temporary instead of a variable declaration?

Why does this call the default constructor?

To create Python virtual environments I use virtualenv and pip. The workflow is very simple:

    $ virtualenv project
    $ cd project
    $ . bin/activate
    $ pip install -r /path/to/requirements/req1.txt
    $ pip install -r /path/to/requirements/req2.txt

The number of different requirement files can grow enough to make handy to have a way to include them at once, so I&#39;d rather prefer to say:

    $ pip install -r /path/to/requirements/req1_req2.txt

with `req1_req2.txt` containing something like:

    include /path/to/requirements/req1.txt
    include /path/to/requirements/req2.txt

or otherwise:

    $ pip install -r /path/to/requirements/*.txt

None of that works and however much simple it could be, I can&#39;t figure out how to do what I want.

Any suggestion?

Split requirements files in pip

A couple of questions concerning this:

 - Is it good practice?
 - Will it, on a large scale, result in better load times?
 - Can it result in browsers &#39;breaking&#39;?
 - Is the same true for the last function in JavaScript  (/jQuery)?

What I mean is stuff like this:

&lt;!-- language: lang-css --&gt;

    #myElement {
      position: absolute;
      top: 0;
      left: 0
    }




Leaving out the last semicolon of a CSS block

I want to make a new key binding to change syntax to, let&#39;s say, HTML or CSS. I searched the official and unofficial documentation to see if there are any answers to my problem.

Content Type	Original Author	Original Content on Stackoverflow
Question	What'sUP	View Question on Stackoverflow
Solution 1 - Excel	Steve	View Answer on Stackoverflow
Solution 2 - Excel	frenchie	View Answer on Stackoverflow
Solution 3 - Excel	Đức Thanh Nguyễn	View Answer on Stackoverflow
Solution 4 - Excel	Steve	View Answer on Stackoverflow

What is the equivalent of "!=" in Excel VBA?

Excel Problem Overview

Excel Solutions

Solution 1 - Excel

Solution 2 - Excel

Solution 3 - Excel

Solution 4 - Excel

Change x axes scale in matplotlib

Is gcc std::unordered_map implementation slow? If so - why?

Attributions