summary from reddit thread about python repetitive code

repetitive_code.md

What are the most repetitive pieces of code that you keep having to write?

summary from reddit thread.

https://www.reddit.com/r/Python/comments/6bjgkt/what_are_the_most_repetitive_pieces_of_code_that/

Class attributes

... class Coordinate(object):
... 
...     def __init__(a, b, c):
...         self.a = a
...         self.b = b
...         self.c = c

attrs

https://attrs.readthedocs.io/en/stable/examples.html

>>> @attr.s
... class Coordinate(object):
...     x = attr.ib()
...     y = attr.ib()
...     z = attr.ib()

collections.namedtuple

NOTE: immutable.

... from collections import namedtuple
... Coordinate = namedtuple('Coordinate', ['x', 'y', 'z'])
... A = Coordinate(1, 2, 3)
... A.x
>>> 1
... A.y (2)
>>> 2
... A.z
>>> 3

__dict__ (not recommended)

... class Coordinate(object):
... 
...     def __init__(a, b, c):
...         self.__dict__.update({k: v for k, v in locals().iteritems() if k != 'self'})

or

... class Coordinate(object):
... 
...     def __init__(self, **kwargs):
...         self.__dict__.update(kwargs)

django

blank=True, null=True

functools.partial

from functools import partial
from sqlalchemy.orm import Column

PKColumn = partial(Column, primary_key=True, autoincrement=True, nullable=False)

data science on jupyter notebook

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
%matplotlib inline
from sklearn import preprocessing, linear_model

import sys
import os
from datetime import datetime, timedelta

baseline.ipynb

https://gist.github.com/Jessime/69df607e4ad5f1229528af2edebe6e70

ipython_config.py

# List of files to run at IPython startup.
c.InteractiveShellApp.exec_lines = [
'%load_ext autoreload',
'%autoreload 2',

# Arrays, dataframes, and trig functions
'import numpy as np',
'from numpy import array, linspace, arange, zeros, ones, \
    eye, sin, cos, tan, arcsin, arccos, arctan, arctan2, log, sqrt',
'np.set_printoptions(suppress=True, precision=4)',
'import pandas as pd',
'from pandas import DataFrame, Series',

# Dates and times
'import saturn',

# Functional programming
'from functools import partial',
'from cytoolz import *',

# Plotting
'import matplotlib',
'from matplotlib import pyplot as plt',
'import fplot',

# Mathematical constants. Import before e, so e is 2.72, not elementary charge.
'from scipy.constants import *',
'ħ = hbar',  # hbar is imported from scipy.constants
'ε_0 = epsilon_0', # from scipy.constants
'Å = angstrom', # from scipy.constants
'import math',
'import cmath',
'from math import e, pi',
'tau = 2 * pi',
'π, τ = pi, tau',
'i = complex(0, 1)',


# Sympy
'import sympy',
'from sympy import diff, integrate, exp, oo, sin as ssin, cos as scos, \
    tan as stan, asin as sasin, acos as sacos, atan as satan, Matrix, simplify, \
    lambdify, Integral, Derivative, factor, expand, limit, var, Eq, N, \
    solveset, linsolve, roots, dsolve, symbols, log as slog, sqrt as ssqrt, \
    cbrt, pi as spi, Rational, linsolve, I',
'from sympy.plotting import plot',
"x, y, z, t = sympy.symbols('x y z t')",
'sympy.init_printing()',
]

Jupyter notebook snippets

http://jupyter-contrib-nbextensions.readthedocs.io/en/latest/nbextensions/snippets/README.html

Setting up arguments

def arguments():
    parser = argparse.ArgumentParser()
    # various arguments
    return parser.parse_args()

click

import click

@click.command()
@click.option('--count', default=1, help='Number of greetings.')
@click.option('--name', prompt='Your name',
              help='The person to greet.')
def hello(count, name):
    """Simple program that greets NAME for a total of COUNT times."""
    for x in range(count):
        click.echo('Hello %s!' % name)

if __name__ == '__main__':
    hello()

docopt

"""Naval Fate.

Usage:
  naval_fate.py ship new <name>...
  naval_fate.py ship <name> move <x> <y> [--speed=<kn>]
  naval_fate.py ship shoot <x> <y>
  naval_fate.py mine (set|remove) <x> <y> [--moored | --drifting]
  naval_fate.py (-h | --help)
  naval_fate.py --version

Options:
  -h --help     Show this screen.
  --version     Show version.
  --speed=<kn>  Speed in knots [default: 10].
  --moored      Moored (anchored) mine.
  --drifting    Drifting mine.

"""
from docopt import docopt


if __name__ == '__main__':
    arguments = docopt(__doc__, version='Naval Fate 2.0')
    print(arguments)```

Reading file

with open(path) as f:
    contents = f.read()

pathlib

contents = pathlib.Path(path).read_text()

pyfilesystem

contents = gettext(path, encoding=None, errors=None, newline=u'')

Logging

log.info('var=%s', `var`)

structlog

>>> from structlog import get_logger
>>> log = get_logger()
>>> log.info("key_value_logging", out_of_the_box=True, effort=0)
2016-04-20 16:20.13 key_value_logging              effort=0 out_of_the_box=True

Parameterized decorators

from functools import wraps

def decorator(argument):
    def real_decorator(function):
        @wraps(function)
        def wrapper(*args, **kwargs):
            funny_stuff()
            something_with_argument(argument)
            retval = function(*args, **kwargs)
            more_funny_stuff()
            return retval
        return wrapper
    return real_decorator

wrapt

import wrapt

@wrapt.decorator
def pass_through(wrapped, instance, args, kwargs):
    return wrapped(*args, **kwargs)

@pass_through
def function():
    pass

version, which accept arguments

import wrapt

def with_arguments(myarg1, myarg2):
    @wrapt.decorator
    def wrapper(wrapped, instance, args, kwargs):
        return wrapped(*args, **kwargs)
    return wrapper

@with_arguments(1, 2)
def function():
    pass

os.walk

import os

# traverse root directory, and list directories as dirs and files as files
for root, dirs, files in os.walk("."):
    for file in files:
        print(len(path) * '---', file)

pyfilesystem

>>> from fs import open_fs
>>> from fs.walk import Walker
>>> home_fs = open_fs('~/projects')
>>> walker = Walker(filter=['*.py'])
>>> for path in walker.files(home_fs):
...     print(path)