Using Alternatives
Many Linux distributions use the alternatives command for switching between different versions of a command. You can use this for switching between different versions of Java installed on a machine.
In a command shell, set $JDK to the pathname of a newly installed JDK; e.g....
Given a DataFrame with MultiIndex columns
# build an example DataFrame
midx = pd.MultiIndex(levels=[['zero', 'one'], ['x','y']], labels=[[1,1,0,],[1,0,1,]])
df = pd.DataFrame(np.random.randn(2,3), columns=midx)
In [2]: df
Out[2]:
one zero
y x ...
Start with a standard DataFrame
df = pd.DataFrame(np.random.randn(2,3), columns=['a','b','c'])
In [91]: df
Out[91]:
a b c
0 -0.911752 -1.405419 -0.978419
1 0.603888 -1.187064 -0.035883
Now to change to MultiIndex, create a MultiIndex object and assign it to df....
You can use the archivesBaseName to set the name of apk.
For example:
defaultConfig {
....
project.ext.set("archivesBaseName", "MyName-" + defaultConfig.versionName);
}
You will obtain this output.
MyName-X.X.X-release.apk
If you need to copy a database from one server to another, you have two options:
Option 1:
Store the dump file in the source server
Copy the dump file to your destination server
Load the dump file into your destination server
On the source server:
mysqldump [options] > dump.sql
On th...
To remove an element from a map use the .delete() method.
map.delete(key);
Example:
const map = new Map([[1, 2], [3, 4]]);
console.log(map.get(3)); // 4
map.delete(3);
console.log(map.get(3)); // undefined
This method returns true if the element existed and has been removed, otherwise fal...
Use .get(key) to get value by key and .set(key, value) to assign a value to a key.
If the element with the specified key doesn't exist in the map, .get() returns undefined.
.set() method returns the map object, so you can chain .set() calls.
const map = new Map();
console.log(map.get(1)); // und...
Setting the state of an object graph (a collection of related entities) to Added is different than setting a single entity as Added (see this example).
In the example, we store planets and their moons:
Class model
public class Planet
{
public Planet()
{
Moons = new HashSet<...
Using requestAnimationFrame may on some systems update at more frames per second than the 60fps. 60fps is the default rate if the rendering can keep up. Some systems will run at 120fps maybe more.
If you use the following method you should only use frame rates that are integer divisions of 60 so th...
Building project dependencies can sometimes be a tedious task. Instead of publishing a package version to NPM and installing the dependency to test the changes, use npm link. npm link creates a symlink so the latest code can be tested in a local environment. This makes testing global tools and proje...
The %timeit magic runs the given code many times, then returns the speed of the fastest result.
In [1]: %timeit sum(range(100000))
100 loops, best of 3: 2.91 ms per loop
The %%timeit cell magic can be used to time blocks of code.
In [2]: %%timeit
...: a = 0
...: for i in range(100000):...
R provides two additional looping constructs, while and repeat, which are typically used in situations where the number of iterations required is indeterminate.
The while loop
The general form of a while loop is as follows,
while (condition) {
## do something
## in loop body
}
whe...
For a class Person like:
public class Person
{
public string Name { get; set; }
public int Age { get; set; }
public string Clothes { get; set; }
}
var person1 = new Person { Name = "Jon", Age = 20, Clothes = "some clothes" };
var person2 = new Person { Name ...
For given type Person:
public class Person
{
public string Name { get; set; }
public int Age { get; set; }
public string Clothes { get; set; }
}
List<Person> persons = new List<Person>
{
new Person{ Name = "Jon", Age = 20, Clothes = "some clothes...
These types are in all versions of SQL Server
datetime
smalldatetime
These types are in all versions of SQL Server after SQL Server 2012
date
datetimeoffset
datetime2
time
This example shows how to render text along an arc. It includes how you can add functionality to the CanvasRenderingContext2D by extending its prototype.
This examples is derived from the stackoverflow answer Circular Text.
Example rendering
Example code
The example adds 3 new text renderi...
Generally execute() command is used for fire and forget calls (without need of analyzing the result) and submit() command is used for analyzing the result of Future object.
We should be aware of key difference of Exception Handling mechanisms between these two commands.
Exceptions from submit() ar...
C++14
C++14 introduced a standard way of deprecating functions via attributes. [[deprecated]] can be used to indicate that a function is deprecated. [[deprecated("reason")]] allows adding a specific reason which can be shown by the compiler.
void function(std::unique_ptr<A> &&a...
Members of objects or classes can be accessed using the object operator (->) and the class operator (::).
class MyClass {
public $a = 1;
public static $b = 2;
const C = 3;
public function d() { return 4; }
public static function e() { return 5; }
}
$object = new MyCl...
#include <iostream>
#include <string>
int main()
{
const char * C_String = "This is a line of text w";
const char * C_Problem_String = "This is a line of text ኚ";
std::string Std_String("This is a second line of text w");
std::string...
