The typing.TypeVar is a generic type factory. It's primary goal is to serve as a parameter/placeholder for generic function/class/method annotations:
import typing
T = typing.TypeVar("T")
def get_first_element(l: typing.Sequence[T]) -> T:
"""Gets the first ele...
Enum constants are instantiated when an enum is referenced for the first time. Therefore, that allows to implement Singleton software design pattern with a single-element enum.
public enum Attendant {
INSTANCE;
private Attendant() {
// perform some initialization routine
...
df = pd.DataFrame({'old_name_1': [1, 2, 3], 'old_name_2': [5, 6, 7]})
print(df)
# Output:
# old_name_1 old_name_2
# 0 1 5
# 1 2 6
# 2 3 7
To rename one or more columns, pass the old names and new names as a dictionary:
df.r...
A generic class with the type parameter Type
class MyGenericClass<Type>{
var value: Type
init(value: Type){
self.value = value
}
func getValue() -> Type{
return self.value
}
func setValue(value: Type){
self.value = value
}...
When adding indented code blocks inside a list you first need a blank line, then to indent the code further. Different flavours of Markdown have different rules for this.
StackExchange requires code to be indented by 8 characters instead of the usual 4. (Spaces replaced with * for clarity):
1...
Examine the following strings:
foobarfoo
bar
foobar
barfoo
the regular expression bar will match all four strings,
\bbar\b will only match the 2nd,
bar\b will be able to match the 2nd and 3rd strings, and
\bbar will match the 2nd and 4th strings.
First of all, we need to add our first Fragment at the beginning, we should do it in the onCreate() method of our Activity:
if (null == savedInstanceState) {
getSupportFragmentManager().beginTransaction()
.addToBackStack("fragmentA")
.replace(R.id.container, FragmentA.n...
So let's suppose you want to iterate only between some specific lines of a file
You can make use of itertools for that
import itertools
with open('myfile.txt', 'r') as f:
for line in itertools.islice(f, 12, 30):
# do something here
This will read through the lines 13 to 20 as i...
Inventory is the Ansible way to track all the systems in your infrastructure. Here is a simple static inventory file containing a single system and the login credentials for Ansible.
[targethost]
192.168.1.1 ansible_user=mrtuovinen ansible_ssh_pass=PassW0rd
Write these lines for example to host...
Define interface
//In this interface, you can define messages, which will be send to owner.
public interface MyCustomListener {
//In this case we have two messages,
//the first that is sent when the process is successful.
void onSuccess(List<Bitmap> bitmapList);
//And Th...
Let's say you have a vector like so:
(def my-vec [1 2 3 4 5 6])
And you want to extract the first 3 elements and get the remaining elements as a sequence. This can be done as follows:
(let [[x y z & remaining] my-vec]
(println "first:" x ", second:" y "third:"...
Swift
textField.textAlignment = .Center
Objective-C
[textField setTextAlignment: NSTextAlignmentCenter];
In the example, we have set the NSTextAlignment to center. You can also set to .Left, .Right, .Justified and .Natural.
.Natural is the default alignment for the current localization. Th...
Given a String and a Character
let text = "Hello World"
let char: Character = "o"
We can count the number of times the Character appears into the String using
let sensitiveCount = text.characters.filter { $0 == char }.count // case-sensitive
let insensitiveCount = text.low...
Add gem to the Gemfile:
gem 'devise'
Then run the bundle install command.
Use command $ rails generate devise:install to generate required configuration file.
Set up the default URL options for the Devise mailer in each environment
In development environment add this line:
config.action_mailer...
If the values in a container have certain operators already overloaded, std::sort can be used with specialized functors to sort in either ascending or descending order:
C++11
#include <vector>
#include <algorithm>
#include <functional>
std::vector<int> v = {5,1,2,4,3};...
From guides.rubyonrails.org:
Instead of generating a model directly . . . let's set up a scaffold. A scaffold in Rails is a full set of model, database migration for that model, controller to manipulate it, views to view and manipulate the data, and a test suite for each of the above.
Here's a...
