Tutorial by Examples: er

Joining a subquery is often used when you want to get aggregate data from a child/details table and display that along with records from the parent/header table. For example, you might want to get a count of child records, an average of some numeric column in child records, or the top or bottom row ...

In ASP.NET Core there are several different ways we can localize/globalize our app. It's important to pick a way that suits your needs. In this example you'll see how we can make a multilingual ASP.NET Core app that reads language specific strings from .json files and store them in memory to provi...

A std::string containing a number can be converted into an integer type, or a floating point type, using conversion functions. Note that all of these functions stop parsing the input string as soon as they encounter a non-numeric character, so "123abc" will be converted into 123. The s...

Arithmetic operations are performed elementwise on Numpy arrays. For arrays of identical shape, this means that the operation is executed between elements at corresponding indices. # Create two arrays of the same size a = np.arange(6).reshape(2, 3) b = np.ones(6).reshape(2, 3) a # array([0, 1...

Alternate return is a facility to control the flow of execution on return from a subroutine. It is often used as a form of error handling: real x call sub(x, 1, *100, *200) print*, "Success:", x stop 100 print*, "Negative input value" stop 200 print*, "Input va...

A subprogram (which defines a procedure), can be either a subroutine or a function; it is said to be an internal subprogram if it is called or invoked from the same program or subprogram that contains it, as follows program my_program ! declarations ! executable statements, ! among which...

A subprogram is said to be external when it is not contained in the main program, nor in a module or antoher subprogram. In particular it can be defined by means of a programming language other than Fortran. When an external subprogram is invoked, the compiler cannot access to its code, so all the ...

Most advanced user interfaces require the user to be able to pass information between the various functions which make up a user interface. MATLAB has a number of different methods to do so. guidata MATLAB's own GUI Development Environment (GUIDE) prefers to use a struct named handles to pass da...

There are various methods available for explicitly converting a string to an integer, such as: Convert.ToInt16(); Convert.ToInt32(); Convert.ToInt64(); int.Parse(); But all these methods will throw a FormatException, if the input string contains non-numeric characters. For t...

Objective-C NSString *textToShare = @"StackOverflow Documentation!! Together, we can do for Documentation what we did for Q&A."; NSURL *documentationURL = [NSURL URLWithString:@"http://stackoverflow.com/tour/documentation"]; NSArray *objectsToShare = @[textToShare, docum...

string str = "this--is--a--complete--sentence"; string[] tokens = str.Split(new[] { "--" }, StringSplitOptions.None); Result: [ "this", "is", "a", "complete", "sentence" ]

It is also possible to use Scala's string interpolation feature to create elaborate extractors (pattern matchers), as perhaps most famously employed in the quasiquotes API of Scala macros. Given that n"p0${i0}p1" desugars to new StringContext("p0", "p1").n(i0), it is p...

When an exception is thrown from within a Future, you can (should) use recover to handle it. For instance, def runFuture: Future = Future { throw new FairlyStupidException } val itWillBeAwesome: Future = runFuture ...will throw an Exception from within the Future. But seeing as we can predic...

If the file does not contain a header row, File: 1;str_data;12;1.4 3;str_data;22;42.33 4;str_data;2;3.44 2;str_data;43;43.34 7; str_data; 25; 23.32 you can use the keyword names to provide column names: df = pandas.read_csv('data_file.csv', sep=';', index_col=0, ski...

generate sample data frames: In [57]: df3 = pd.DataFrame({'col1':[211,212,213], 'col2': [221,222,223]}) In [58]: df1 = pd.DataFrame({'col1':[11,12,13], 'col2': [21,22,23]}) In [59]: df2 = pd.DataFrame({'col1':[111,112,113], 'col2': [121,122,123]}) In [60]: df3 = pd.DataFrame({'col1':[211,2...

The pattern matching library trivia provides a system trivia.ppcre that allows captured groups to be bound through pattern matching (trivia:match "John Doe" ((trivia.ppcre:ppcre "(.*)\\W+(.*)" first-name last-name) (list :first-name first-name :last-name last-name))) ;...

Common Lisp has a standard, which was initially published in 1994 as an ANSI standard. The Common Lisp HyperSpec, short CLHS, provided by LispWorks is an often used HTML documentation, which is derived from the standard document. The HyperSpec can also be downloaded and locally used. Common Lisp d...

Given this object: var obj = { a: "hello", b: "this is", c: "javascript!", }; You can convert its values to an array by doing: var array = Object.keys(obj) .map(function(key) { return obj[key]; }); console.log(array); // [&quot...

CREATE DATABASE stackoverflow; USE stackoverflow; Create table stack( id_user int NOT NULL, username varchar(30) NOT NULL, password varchar(30) NOT NULL ); ALTER TABLE stack ADD COLUMN submit date NOT NULL; -- add new column ALTER TABLE stack DROP COLUMN submit; -- drop col...

itertools.combinations will return a generator of the k-combination sequence of a list. In other words: It will return a generator of tuples of all the possible k-wise combinations of the input list. For Example: If you have a list: a = [1,2,3,4,5] b = list(itertools.combinations(a, 2)) print ...