>>> '{0:.0f}'.format(42.12345)
'42'
>>> '{0:.1f}'.format(42.12345)
'42.1'
>>> '{0:.3f}'.format(42.12345)
'42.123'
>>> '{0:.5f}'.format(42.12345)
'42.12345'
>>> '{0:.7f}'.format(42.12345)
'42.1234500'
Same hold for other way of referenc...
You can also use regular expressions to split a string. For example,
import re
data = re.split(r'\s+', 'James 94 Samantha 417 Scarlett 74')
print( data )
# Output: ['James', '94', 'Samantha', '417', 'Scarlett', '74']
You can get rid of manage.py and use the django-admin command instead. To do so, you will have to manually do what manage.py does:
Add your project path to your PYTHONPATH
Set the DJANGO_SETTINGS_MODULE
export PYTHONPATH="/home/me/path/to/your_project"
export DJANGO_SETTINGS_MODULE...
IList<T> is never a subtype of a different IList<T1>. IList is invariant in its type parameter.
class Animal { /* ... */ }
class Dog : Animal { /* ... */ }
IList<Dog> dogs = new List<Dog>();
IList<Animal> animals = dogs; // type error
There is no subtype relat...
If you have a vsix file, you can install it by running the file.
Get the vsix file (this is the extension installer)
Run the file.
In the window that opens, confirm the installation.
In Visual studio
go to Tools > Extensions and updates...
In the window that opens go to online
Select Visual Studio Gallery
You can search for an extension on the search box at the upper right corner
Select the extension you want to add
Click on download.
Once download is complete, click...
int x = 5 / 0; // Undefined behavior
Division by 0 is mathematically undefined, and as such it makes sense that this is undefined behavior.
However:
float x = 5.0f / 0.0f; // x is +infinity
Most implementation implement IEEE-754, which defines floating point division by zero to return N...
int x = INT_MAX + 1;
// x can be anything -> Undefined behavior
If during the evaluation of an expression, the result is not mathematically defined or not in the range of representable values for its type, the behavior is undefined.
(C++11 Standard paragraph 5/4)
This is one of the mo...
To add annotations, hints, or exclude some code from being executed JavaScript provides two ways of commenting code lines
Single line Comment //
Everything after the // until the end of the line is excluded from execution.
function elementAt( event ) {
// Gets the element from Event coordinate...
By default, Django renders ForeignKey fields as a <select> input. This can cause pages to be load really slowly if you have thousands or tens of thousand entries in the referenced table. And even if you have only hundreds of entries, it is quite uncomfortable to look for a particular entry amo...
Using threading & queue:
from socket import socket, AF_INET, SOCK_STREAM
from threading import Thread
from queue import Queue
def echo_server(addr, nworkers):
print('Echo server running at', addr)
# Launch the client workers
q = Queue()
for n in range(nworkers):
...
Interfaces may have variant type parameters.
interface IEnumerable<out T>
{
// ...
}
interface IComparer<in T>
{
// ...
}
but classes and structures may not
class BadClass<in T1, out T2> // not allowed
{
}
struct BadStruct<in T1, out T2> // not allo...
Differences in subsetting syntax
A data.table is one of several two-dimensional data structures available in R, besides data.frame, matrix and (2D) array. All of these classes use a very similar but not identical syntax for subsetting, the A[rows, cols] schema.
Consider the following data stored i...
Category theory is a modern mathematical theory and a branch of abstract algebra focused on the nature of connectedness and relation. It is useful for giving solid foundations and common language to many highly reusable programming abstractions. Haskell uses Category theory as inspiration for some o...
A category C consists of:
A collection of objects called Obj(C) ;
A collection (called Hom(C)) of morphisms between those objects. If a and b are in Obj(C), then a morphism f in Hom(C) is typically denoted f : a -> b, and the collection of all morphism between a and b is denoted hom(a,b) ;
A...
Using Kestrel you can specify port using next approaches:
Defining ASPNETCORE_URLS environment variable.
Windows
SET ASPNETCORE_URLS=https://0.0.0.0:5001
OS X
export ASPNETCORE_URLS=https://0.0.0.0:5001
Via command line passing --server.urls parameter
dotnet run --server.urls=http...
When configuring the built-in logging functionality, a common pattern is to create a logger with the __name__ of the current module:
logger = logging.getLogger(__name__)
This means that the fully-qualified name of the module will appear in the logs, making it easier to see where messages have co...
If you have a string that contains Python literals, such as strings, floats etc, you can use ast.literal_eval to evaluate its value instead of eval. This has the added feature of allowing only certain syntax.
>>> import ast
>>> code = """(1, 2, {'foo': 'bar'})"...
It is not possible to use eval or exec to execute code from untrusted user securely. Even ast.literal_eval is prone to crashes in the parser. It is sometimes possible to guard against malicious code execution, but it doesn't exclude the possibility of outright crashes in the parser or the tokenizer....
