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dplyr::filter() - Select a subset of rows in a data frame that meet a logical criteria: dplyr::filter(iris,Sepal.Length>7) # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 7.1 3.0 5.9 2.1 virginica # 2 7.6 3.0 ...

An interesting but rather unknown usage of Active Patterns in F# is that they can be used to validate and transform function arguments. Consider the classic way to do argument validation: // val f : string option -> string option -> string let f v u = let v = defaultArg v "Hello&quo...

eof returns true only after reading the end of file. It does NOT indicate that the next read will be the end of stream. while (!f.eof()) { // Everything is OK f >> buffer; // What if *only* now the eof / fail bit is set? /* Use `buffer` */ } You could correctly write: ...

Using Derived column we can prepare the input. We will provide yyyy-MM-dd to the final conversion: Year: (DT_STR,4,1252)(DataDate / 10000) Month: (DT_STR,2,1252)(DataDate / 100 % 100) Day: (DT_STR,2,1252)(DataDate % 100) All together: (DT_DBDATE)((DT_STR,4,1252)(DataDate / 10000) + "-&q...

When an object is exposed to the template context, its arguments-less methods are available. This is useful when these functions are "getters". But it can be hazardeous if these methods alter some data or have some side effects. Eventhough you likely trust the template writer, he may not b...

Basic assembly support with gcc has the following syntax: asm [ volatile ] ( AssemblerInstructions ) where AssemblerInstructions is the direct assembly code for the given processor. The volatile keyword is optional and has no effect as gcc does not optimize code within a basic asm statement. A...

This attribute is used to give a name to this particular assembly. [assembly: AssemblyTitle("MyProduct")]

This attribute is used to describe the product that this particular assembly is for. Multiple assemblies can be components of the same product, in which case they can all share the same value for this attribute. [assembly: AssemblyProduct("MyProduct")]

When working with large files, you can use the System.IO.File.ReadLines method to read all lines from a file into an IEnumerable<string>. This is similar to System.IO.File.ReadAllLines, except that it doesn't load the whole file into memory at once, making it more efficient when working with l...

Ada 2012(TC-1) with Ada.Text_IO; procedure Main is type Some_Float digits 8 range 0.0 .. 10.0; X : Some_Float := 2.71; begin Ada.Text_IO.Put_Line (X'Image); end Main; Result 2.71000E+00

Ada 2012(TC-1) with Ada.Text_IO; procedure Main is type Some_Integer is range -42 .. 42; X : Some_Integer := 17; begin Ada.Text_IO.Put_Line (X'Image); end Main; Result 17

Ada 2012(TC-1) with Ada.Text_IO; procedure Main is type Fruit is (Banana, Orange, Pear); X : Fruit := Orange; begin Ada.Text_IO.Put_Line (X'Image); Ada.Text_IO.Put_Line (Pear'Image); end Main; Result ORANGE PEAR

Jupyter Notebooks are an interactive, browser-based development environment. They were originally developed to run computation python and as such play very well with numpy. To try numpy in a Jupyter notebook without fully installing either on one's local system Rackspace provides free temporary note...

SQL has various join types to specify whether (non-)matching rows are included in the result: INNER JOIN, LEFT OUTER JOIN, RIGHT OUTER JOIN, and FULL OUTER JOIN (the INNER and OUTER keywords are optional). The figure below underlines the differences between these types of joins: the blue area repres...

It might be easier if you think of GROUP BY as "for each" for the sake of explanation. The query below: SELECT EmpID, SUM (MonthlySalary) FROM Employee GROUP BY EmpID is saying: "Give me the sum of MonthlySalary's for each EmpID" So if your table looked like this: +----...

I created custom label with wrapper around FormattedText property: public class MultiComponentLabel : Label { public IList<TextComponent> Components { get; set; } public MultiComponentLabel() { var components = new ObservableCollection<TextComponent>(); ...

If you do row-by-row processing in Salesforce, you'll probably reach the governor limit quickly. This is especially true with triggers and things that fire when you don't expect them. One documented method of escaping the governor limit is bulkification. Note: The following information is based on ...

The MyBase keyword behaves like an object variable that refers to the base class of the current instance of a class. Public Class Person Public Sub DoSomething() Console.WriteLine("Person") End Sub End Class Public Class Customer Inherits Person Public S...

Singleton classes share their instance/class variables with their object. class Example @@foo = :example end def Example.foo class_variable_get :@@foo end Example.foo #=> :example class Example def initialize @foo = 1 end def foo @foo end end e = Ex...

0.18.0 Model is passed to subscriptions which means that every state change can modify subscriptions. import Html exposing ( Html, div, text, button ) import Html.Events exposing ( onClick ) import Time main : Program Never Model Msg main = Html.program { init = init ,...