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Vlookup finds some value in the leftmost column of a range and returns a value some number of columns to the right and in the same row. Let's say you want to find the surname of Employee ID 2 from this table: =VLOOKUP(2,$A$2:$C$4,3,0) The value you're retrieving data for is 2 The table you...

Knitr is an R package that allows us to intermingle R code with LaTeX code. One way to achieve this is external code chunks. External code chunks allow us to develop/test R Scripts in an R development environment and then include the results in a report. It is a powerful organizational technique....

This function executes an AJAX request using the HEAD method allowing us to check whether a file exists in the directory given as an argument. It also enables us to launch a callback for each case (success, failure). function fileExists(dir, successCallback, errorCallback) { var xhttp = new XM...

The most common conditional in Julia is the if...else expression. For instance, below we implement the Euclidean algorithm for computing the greatest common divisor, using a conditional to handle the base case: mygcd(a, b) = if a == 0 abs(b) else mygcd(b % a, a) end The if...else for...

In performing parsing, before starting, the grammar for the language needs to be specified. A source of tokens is also needed for the parser. The parser could be hand-written code, or a parser generator tool could be used. If a parser generator tool is used, then that tool will need to be downloade...

Every time a program opens a resource, such as a file or network connection, it is important to free the resource once you are done using it. Similar caution should be taken if any exception were to be thrown during operations on such resources. One could argue that the FileInputStream has a finaliz...

The tree command lists the contents of a specified directory in a tree-like format. If no directory is specified then, by default, the contents of the current directory are listed. Example Output: $ tree /tmp /tmp ├── 5037 ├── adb.log └── evince-20965    └── image.FPWTJY.png Use the tree ...

If you have nested lists, it is desireable to clone the nested lists as well. This action is called deep copy. >>> import copy >>> c = [[1,2]] >>> d = copy.deepcopy(c) >>> c is d False >>> c[0] is d[0] False

Error handling is important but can make an elegant algorithm into a mess. Railway Oriented Programming (ROP) is used to make error handling elegant and composable. Consider the simple function f: let tryParse s = let b, v = System.Int32.TryParse s if b then Some v else None let f (g : ...

One of the easiest examples of using shared services is when we want to store some data from a given page of our application, and then get that data again but from another page. One option could be to send that data as a parameter (for instance, if one page calls the other one) but if we want to us...

UITextView has extra paddings by default. Sometimes it's annoying especially if you want to measure some text without view instance and place them at some area precisely. Do this to remove such paddings. messageTextView.textContainerInset = UIEdgeInsetsZero messageTextView.textContainer.lineFragm...

attr() gets/sets the HTML attribute using the DOM functions getAttribute() and setAttribute(). prop() works by setting the DOM property without changing the attribute. In many cases the two are interchangeable, but occasionally one is needed over the other. To set a checkbox as checked: $('#tosAcc...

Like normal HTML elements, it is possible for $scopes to have their own events. $scope events can be subscribed to using the following manner: $scope.$on('my-event', function(event, args) { console.log(args); // { custom: 'data' } }); If you need unregister an event listener, the $on func...

It is very easy to pass information between threads using the MVar a type and its accompanying functions in Control.Concurrent: newEmptyMVar :: IO (MVar a) -- creates a new MVar a newMVar :: a -> IO (MVar a) -- creates a new MVar with the given value takeMVar :: MVar a -> IO a -- retrieve...

Summary: MVVM is an architectural pattern that is represented by three distinct components, the Model, View and ViewModel. In order to understand these three layers, it is necessary to briefly define each, followed by an explanation of how they work together. Model is the layer that drives the bus...

This is an simple example to create a mysql server with docker 1.- create docker-compose.yml: Note: If you want to use same container for all your projects, you should create a PATH in your HOME_PATH. If you want to create it for every project you could create a docker directory in your project. ...

This example inserts/sends the current day of the week's full name (e.g. Sunday) whenever Ctrl + Alt + D is pressed: ^!d::Send, %A_DDDD%

(defun print-entry (key value) (format t "~A => ~A~%" key value)) (maphash #'print-entry *my-table*) ;; => NIL Using maphash allows to iterate over the entries of a hash table. The order of iteration is unspecified. The first argument is a function accepting two parameters: ...

Extractor behavior can be used to derive arbitrary values from their input. This can be useful in scenarios where you want to be able to act on the results of a transformation in the event that the transformation is successful. Consider as an example the various user name formats usable in a Window...

String#at Returns a substring of a string object. Same interface as String#[]. str = "hello" str.at(0) # => "h" str.at(1..3) # => "ell" str.at(-2) # => "l" str.at(-2..-1) # => "lo" str.at(5) # => nil str.at(5..-...