Tutorial by Examples: en

Although GameplayKit (which is introduced with iOS 9 SDK) is about implementing game logic, it could also be used to generate random numbers, which is very useful in apps and games. Beside the GKRandomSource.sharedRandom which is used in the following chapters there are three additional types of GK...

If a type t is Traversable then values of t a can be split into two pieces: their "shape" and their "contents": data Traversed t a = Traversed { shape :: t (), contents :: [a] } where the "contents" are the same as what you'd "visit" using a Foldable insta...

However, x in the generator expression is not just variable, but can be any pattern. In cases of pattern mismatch the generated element is skipped over, and processing of the list continues with the next element, thus acting like a filter: [x | Just x <- [Just 1, Nothing, Just 3]] -- [1, 3] ...

List comprehensions can also draw elements from multiple lists, in which case the result will be the list of every possible combination of the two elements, as if the two lists were processed in the nested fashion. For example, [ (a,b) | a <- [1,2,3], b <- ['a','b'] ] -- [(1,'a'), (1,'b'),...

With Parallel List Comprehensions language extension, [(x,y) | x <- xs | y <- ys] is equivalent to zip xs ys Example: [(x,y) | x <- [1,2,3] | y <- [10,20]] -- [(1,10),(2,20)]

You could use ethtool, but they are not going to be reboot persistent. If you want to achieve this, edit the following file: sudo vim /etc/network/interfaces And edit the file with needed informations: auto <interface_name> iface <interface_name> inet static address <ip_addres...

The function np.loadtxt can be used to read csv-like files: # File: # # Col_1 Col_2 # 1, 1 # 2, 4 # 3, 9 np.loadtxt('/path/to/dir/csvlike.txt', delimiter=',', comments='#') # Output: # array([[ 1., 1.], # [ 2., 4.], # [ 3., 9.]]) The same file could be read ...

# example data DT = as.data.table(mtcars, keep.rownames = TRUE) To rename a column (while keeping its data the same), there is no need to copy the data to a column with a new name and delete the old one. Instead, we can use setnames(DT, "mpg_sq", "mpq_squared") to modify ...

Batch file command line arguments are parameter values submitted when starting the batch. They should be enclosed in quotes if they contain spaces. In a running batch file, the arguments are used for various purposes, i.e. redirection to :labels, setting variables, or running commands. The argument...

When more than 9 arguments are supplied, the shift [/n] command can be used, where /n means start at the nth argument, n is between zero and eight. Looping through arguments: :args set /a "i+=1" set arg!i!=%~1 call echo arg!i! = %%arg!i!%% shift goto :args Note, in the above exam...

Let's create an Enumerator for Fibonacci numbers. fibonacci = Enumerator.new do |yielder| a = b = 1 loop do yielder << a a, b = b, a + b end end We can now use any Enumerable method with fibonacci: fibonacci.take 10 # => [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]

If you want to clear your current Activity stack and launch a new Activity (for example, logging out of the app and launching a log in Activity), there appears to be two approaches. 1. Target (API >= 16) Calling finishAffinity() from an Activity 2. Target (11 <= API < 16) Intent intent ...

You can do a permissions check when sending an Intent to a registered broadcast receiver. The permissions you send are cross-checked with the ones registered under the tag. They restrict who can send broadcasts to the associated receiver. To send a broadcast request with permissions, specify the p...

This is a TCP daytime client kept as simple as possible. #include <unistd.h> /* unix standard library */ #include <arpa/inet.h> /* IP addresses manipulation utilities */ #include <netinet/in.h> /* sockaddr_in structure definition */ #include <sys/socket.h> /* ber...

ActionMailer also allows attaching files. attachments['filename.jpg'] = File.read('/path/to/filename.jpg') By default, attachments will be encoded with Base64. To change this, you can add a hash to the attachments method. attachments['filename.jpg'] = { mime_type: 'application/gzip', enco...

Sometimes conversion of primitive types to boxed types is necessary. To convert the array, it's possible to use streams (in Java 8 and above): Java SE 8 int[] primitiveArray = {1, 2, 3, 4}; Integer[] boxedArray = Arrays.stream(primitiveArray).boxed().toArray(Integer[]::new); With lowe...

Non-clustered indexes have a structure separate from the data rows. A non-clustered index contains the non-clustered index key values and each key value entry has a pointer to the data row that contains the key value. There can be maximum 999 non-clustered index on SQL Server 2008/ 2012. Link for r...

Generators are functions which are able to pause and then resume execution. This allows to emulate async functions using external libraries, mainly q or co. Basically it allows to write functions that wait for async results in order to go on: function someAsyncResult() { return Promise.resolve...

Insert a document called 'myFirstDocument' and set 2 properties, greetings and farewell const MongoClient = require('mongodb').MongoClient; const url = 'mongodb://localhost:27017/test'; MongoClient.connect(url, function (err, db) { if (err) throw new Error(err); db.collection('myCollect...

Find a document with the property { greetings: 'Hellu' } and change it to { greetings: 'Whut?' } const MongoClient = require('mongodb').MongoClient; const url = 'mongodb://localhost:27017/test'; MongoClient.connect(url, function (err, db) { if (err) throw new Error(err); db.collecti...