Get all ice cream cones that were ordered by people liking chocolate:
IceCream.objects.filter(metadata__buyer__favorite_flavor='chocolate')
See the note in the "Remarks" section about chaining queries.
An integer will be interpreted as an index lookup.
IceCream.objects.filter(metadata__buyer__known_for__0='creating stack overflow')
See the note in the "Remarks" section about chaining queries.
vimtutor is an interactive tutorial covering the most basic aspects of text editing.
On UNIX-like system, you can start the tutorial with:
$ vimtutor
On Windows, “Vim tutor” can be found in the “Vim 7.x” directory under “All Programs” in the Windows menu.
See :help vimtutor for further details...
You can create a TCP server using the socketserver library.
Here's a simple echo server.
Server side
from sockerserver import BaseRequestHandler, TCPServer
class EchoHandler(BaseRequestHandler):
def handle(self):
print('connection from:', self.client_address)
while True:...
A UDP server is easily created using the socketserver library.
a simple time server:
import time
from socketserver import BaseRequestHandler, UDPServer
class CtimeHandler(BaseRequestHandler):
def handle(self):
print('connection from: ', self.client_address)
# Get message and cli...
The vast majority of Python memory management is handled with reference counting.
Every time an object is referenced (e.g. assigned to a variable), its reference count is automatically increased. When it is dereferenced (e.g. variable goes out of scope), its reference count is automatically decreas...
Python is a hybrid interpreter. When running a program, it first assembles it into bytecode which can then be run in the Python interpreter (also called a Python virtual machine). The dis module in the standard library can be used to make the Python bytecode human-readable by disassembling classes, ...
The iloc (short for integer location) method allows to select the rows of a dataframe based on their position index. This way one can slice dataframes just like one does with Python's list slicing.
df = pd.DataFrame([[11, 22], [33, 44], [55, 66]], index=list("abc"))
df
# Out:
# 0...
Using the timeit module from the command line:
> python -m timeit 'for x in xrange(50000): b = x**3'
10 loops, best of 3: 51.2 msec per loop
> python -m timeit 'from math import pow' 'for x in xrange(50000): b = pow(x,3)'
100 loops, best of 3: 9.15 msec per loop
The built-in ** operato...
To get basic information about a DataFrame including the column names and datatypes:
import pandas as pd
df = pd.DataFrame({'integers': [1, 2, 3],
'floats': [1.5, 2.5, 3],
'text': ['a', 'b', 'c'],
'ints with None': [1, None, 3]})
...
SilverStripe can be installed via composer or through the extraction of downloaded zip file.
To install through composer we run the following command
composer create-project silverstripe/installer /path/to/project 3.4.0
A download zip file can be found on the download page of the SilverStripe w...
You can validate any object, even plain ruby.
class User
include ActiveModel::Validations
attr_reader :name, :age
def initialize(name, age)
@name = name
@age = age
end
validates :name, presence: true
validates :age, numericality: { only_integer: true, greater_than...
You can use an initializer to set default property values:
struct Example {
var upvotes: Int
init() {
upvotes = 42
}
}
let myExample = Example() // call the initializer
print(myExample.upvotes) // prints: 42
Or, specify default property values as a part of the property...
Using the idiom from The Manual Way several times in a script soon gets tedious so you might want to try a module.
use Path::Tiny;
my $contents = path($filename)->slurp;
You can pass a binmode option if you need control over file encodings, line endings etc. - see man perlio:
my $contents =...
Quaternion.LookRotation(Vector3 forward [, Vector3 up]) will create a Quaternion rotation that looks forward 'down' the forward vector and has the Y axis aligned with the 'up' vector. If the up vector is not specified, Vector3.up will be used.
Rotate this Game Object to look at a target Game Object...
A recursive function is simply a function, that would call itself.
function factorial (n) {
if (n <= 1) {
return 1;
}
return n * factorial(n - 1);
}
The above function shows a basic example of how to perform a recursive function to return a factorial.
Another...
