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After creating a new model or modifying existing models, you will need to generate migrations for your changes and then apply the migrations to the specified database. This can be done by using the Django's built-in migrations system. Using the manage.py utility when in the project root directory: ...

Statistical functions in R make heavy use of the so-called Wilkinson-Rogers formula notation1 . When running model functions like lm for the Linear Regressions, they need a formula. This formula specifies which regression coefficients shall be estimated. my_formula1 <- formula(mpg ~ wt) class(...

class Animal def method_missing(method, *args, &block) say, speak = method.to_s.split("_") if say == "say" speak else super end end end => a = Animal.new => a.say_moo => "moo" => a.shout_moo => NoMethodE...

Say you want to perform in action (in this case, logging "Foo"), while doing something else (logging "Bar"). Normally, if you don't use concurrency, one of these actions is going to be fully executed, and the other run will run only after it's completely finished. But with concur...

c := exec.Command(name, arg...) b := &bytes.Buffer{} c.Stdout = b c.Stdin = stdin if err := c.Start(); err != nil { return nil, err } timedOut := false intTimer := time.AfterFunc(timeout, func() { log.Printf("Process taking too long. Interrupting: %s %s", name, strings...

cmd := exec.Command("sleep", "5") // Does not wait for command to complete before returning err := cmd.Start() if err != nil { log.Fatal(err) } // Wait for cmd to Return err = cmd.Wait() log.Printf("Command finished with error: %v", err)

A popular form of data analysis is split-apply-combine, in which you split your data into groups, apply some sort of processing on each group, and then combine the results. Let's consider a data analysis where we want to obtain the two cars with the best miles per gallon (mpg) for each cylinder cou...

To catch a long click and use it you need to provide appropriate listener to button: View.OnLongClickListener listener = new View.OnLongClickListener() { public boolean onLongClick(View v) { Button clickedButton = (Button) v; String buttonText = clickedButton.getText().toStri...

As Array conforms to SequenceType, we can use map(_:) to transform an array of A into an array of B using a closure of type (A) throws -> B. For example, we could use it to transform an array of Ints into an array of Strings like so: let numbers = [1, 2, 3, 4, 5] let words = numbers.map { Stri...

ThenBy can only be used after a OrderBy clause allowing to order using multiple criteria var persons = new[] { new {Id = 1, Name = "Foo", Order = 1}, new {Id = 1, Name = "FooTwo", Order = 2}, new {Id = 2, Name = "Bar", Order = 2}, new {Id = 2, Nam...

Migrations in a Laravel 5 application live in the database/migrations directory. Their filenames conform to a particular format: <year>_<month>_<day>_<hour><minute><second>_<name>.php One migration file should represent a schema update to solve a particu...

Run-length encoding captures the lengths of runs of consecutive elements in a vector. Consider an example vector: dat <- c(1, 2, 2, 2, 3, 1, 4, 4, 1, 1) The rle function extracts each run and its length: r <- rle(dat) r # Run Length Encoding # lengths: int [1:6] 1 3 1 1 2 2 # valu...

One of the first questions people have when they begin to use PowerShell for scripting is how to manipulate the output from a cmdlet to perform another action. The pipeline symbol | is used at the end of a cmdlet to take the data it exports and feed it to the next cmdlet. A simple example is using...

The MATLAB Profiler is a tool for software profiling of MATLAB code. Using the Profiler, it is possible to obtain a visual representation of both execution time and memory consumption. Running the Profiler can be done in two ways: Clicking the "Run and Time" button in the MATLAB GUI...

Python 3.x3.3 Use yield from if you want to yield all values from another iterable: def foob(x): yield from range(x * 2) yield from range(2) list(foob(5)) # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1] This works with generators as well. def fibto(n): a, b = 1, 1 while True: ...

This a basic example aimed at new users. It does not focus on explaining the difference between char and cellstring. It might happen that you want to get rid of the ' in your strings, although you never added them. In fact, those are artifacts that the command window uses to distinguish between ...

--- trim: a string-trimming module for Lua -- Author, date, perhaps a nice license too -- -- The code here is taken or adapted from material in -- Programming in Lua, 3rd ed., Roberto Ierusalimschy -- trim_all(string) => return string with white space trimmed on both sides local trim_al...

-- The following assumes that trim module is installed or in the caller's package.path, -- which is a built-in variable that Lua uses to determine where to look for modules. local trim = require "trim" local msg = " Hello, world! " local cleaned = trim.trim_all(msg)...

<PROJECT_ROOT>\app\build.gradle is specific for app module. <PROJECT_ROOT>\build.gradle is a "Top-level build file" where you can add configuration options common to all sub-projects/modules. If you use another module in your project, as a local library you would have another...

The where statement may be used within a switch case match to add additional criteria required for a positive match. The following example checks not only for the range, but also if the number is odd or even: switch (temperature) { case 0...49 where temperature % 2 == 0: print(&quot...