Tutorial by Examples: u

cycle is an infinite iterator. >>> import itertools as it >>> it.cycle('ABCD') A B C D A B C D A B C D ... Therefore, take care to give boundaries when using this to avoid an infinite loop. Example: >>> # Iterate over each element in cycle for a fixed range >&g...
When to use abstract classes: To implement the same or different behaviour among multiple related objects When to use interfaces: to implement a contract by multiple unrelated objects Abstract classes create "is a" relations while interfaces provide "has a" capability. This c...
sudo apt-add-repository ppa:brightbox/ruby-ng Hit Enter to confirm sudo apt-get update Then you can install your ruby version of choice (the ppa supports ruby2.0 ruby2.1 ruby2.2 ruby2.3 and legacy versions ruby1.8 ruby1.9.1) Don't forget to include the respective -dev package for your version. Ot...
Create Or Replace Function Generateguid Return Char Is V_Guid Char(40); Begin Select Substr(Sys_Guid(),1,8)||'-'||Substr(Sys_Guid(),9,4)||'-' ||Substr(Sys_Guid(),13,4)||'-'||Substr(Sys_Guid(),17,4)||'-' ||Substr(Sys_Guid(),21) Into V_Guid...
Disclaimer: In no way does this example advocate the use of singletons. Singletons are to be used with a lot of care. In PHP there is quite a standard way of implementing a singleton: public class Singleton { private $instance; private function __construct() { }; public function...
To see all the facts involving the le relation from the prelude: Coq < Search le. le_n: forall n : nat, n <= n le_S: forall n m : nat, n <= m -> n <= S m ... max_l: forall n m : nat, m <= n -> Nat.max n m = n max_r: forall n m : nat, n <= m -> Nat.max n m = m ... ...
Session Types are a way to tell the compiler about the protocol you want to use to communicate between threads - not protocol as in HTTP or FTP, but the pattern of information flow between threads. This is useful since the compiler will now stop you from accidentally breaking your protocol and causi...
uses SysUtils; var S1, S2: string; begin S1 := 'Foo'; S2 := LowerCase(S1); // S2 := 'foo'; S1 := UpperCase(S2); // S1 := 'FOO';
Let's say your launch activity is called MainActivity, in your app com.example.myapp. In the manifest: <activity android:name=".MainActivity" > <intent-filter> <action android:name="android.intent.action.MAIN"/> ...
SELECT SYSDATE(); This function returns the current date and time as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context. It returns the date and time in the current time zone. SELECT NOW(); This function is a...
The dimension attribute on an object specifies that that object is an array. There are, in Fortran 2008, five array natures:1 explicit shape assumed shape assumed size deferred shape implied shape Take the three rank-1 arrays2 integer a, b, c dimension(5) a ! Explicit shape (default ...
example: df = pd.DataFrame({'group1' : ['A', 'A', 'A', 'A', 'B', 'B', 'B', 'B'], 'group2' : ['C', 'C', 'C', 'D', 'E', 'E', 'F', 'F'], 'B' : ['one', np.NaN, np.NaN, np.NaN, ...
If the value of the href-attribute begins with tel:, your device will dial the number when you click it. This works on mobile devices or on computers/tablets running software – like Skype or FaceTime – that can make phone calls. <a href="tel:11234567890">Call us</a> Most de...
SUB function allows to substitute text inside awk sub(regexp, replacement, target) where regexp could be a full regular expression $ cat file AAAAA BBBB CCCC DDDD EEEE FFFF GGGG $ awk '{sub("AAA","XXX", $0); print}' file XXXAA BBBB CCCC DDDD EEEE FFFF GGGG ...
(This is a request for a good example that shows how to construct a SELECT using CONCAT, then prepare+execute it. Please emphasize the use of @variables versus DECLAREd variables -- it makes a big difference, and it is something that novices (include myself) stumble over.)
# example data DT = data.table(iris) DT[, Bin := cut(Sepal.Length, c(4,6,8))] summary is handy for browsing summary statistics. Besides direct usage like summary(DT), it can also be applied per-group conveniently with split: lapply(split(DT, by=c("Species", "Bin"), drop=TRU...
# example data DT = data.table(iris) DT[, Bin := cut(Sepal.Length, c(4,6,8))] To apply the same summarizing function to every column by group, we can use lapply and .SD DT[, lapply(.SD, median), by=.(Species, Bin)] # Species Bin Sepal.Length Sepal.Width Petal.Length Petal.Width # 1...
Setup Ruby On Rails on Ubuntu 16.04 Xenial Xerus All commands should be run in Linux terminal (hotkey: Ctrl + Alt + T) You need to install Ruby on your local machine in development environment. The first step is to install some dependencies for Ruby. sudo apt-get update sudo apt-get install git...
JUnit is the leading testing framework used for testing Java code. The class under test models a simple bank account, that charges a penalty when you go overdrawn. public class BankAccount { private int balance; public BankAccount(int i){ balance = i; } public Bank...
In molecular biology and genetics, GC-content (or guanine-cytosine content, GC% in short) is the percentage of nitrogenous bases on a DNA molecule that are either guanine or cytosine (from a possibility of four different ones, also including adenine and thymine). Using BioPython: >>> from...

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