Python ticks quick reference
pdb/ipdb
https://docs.python.org/3/library/pdb.html
https://github.com/gotcha/ipdb
pdb
import pdb; pdb.set_trace()
ipdb
import ipdb
ipdb.set_trace()
list comprehension
>> [i for i in range(10) if i != 5]
output
[0, 1, 2, 3, 4, 6, 7, 8, 9]
列出object properties
>> vars(<object>)
f-string
>> a = 1234
>> print(f"a = {a}")
a = 1234
yield - send
asyncio
PEP 492
https://docs.python.org/3/library/asyncio-task.html#coroutines
simple example
async def main():
task1 = asyncio.create_task(
say_after(1, 'hello'))
task2 = asyncio.create_task(
say_after(2, 'world'))
print(f"started at {time.strftime('%X')}")
# Wait until both tasks are completed (should take
# around 2 seconds.)
await task1
await task2
print(f"finished at {time.strftime('%X')}")
Running Tasks Concurrently
import asyncio
async def factorial(name, number):
f = 1
for i in range(2, number + 1):
print(f"Task {name}: Compute factorial({i})...")
await asyncio.sleep(1)
f *= i
print(f"Task {name}: factorial({number}) = {f}")
async def main():
# Schedule three calls *concurrently*:
await asyncio.gather(
factorial("A", 2),
factorial("B", 3),
factorial("C", 4),
)
asyncio.run(main())
# Expected output:
#
# Task A: Compute factorial(2)...
# Task B: Compute factorial(2)...
# Task C: Compute factorial(2)...
# Task A: factorial(2) = 2
# Task B: Compute factorial(3)...
# Task C: Compute factorial(3)...
# Task B: factorial(3) = 6
# Task C: Compute factorial(4)...
# Task C: factorial(4) = 24
multiprocessing
multithreading
concurrent
Encoding declarations
https://docs.python.org/3.6/reference/lexical_analysis.html#encoding-declarations
Put the follow comment in the first or second line of the Python script:
-*- coding: <encoding-name> -*-
取得環境變數
import os
os.environ.get('X509_USER_PROXY')
min
這是特別的用法
>>> a = [{"test":{"val1":1}, "name":"A"}, {"test":{"val1":2}, "name": "B"}]
>>> min(a, key=lambda k: k["test"]["val1"])
{'test': {'val1': 1}, 'name': 'A'}
zip
>>> list(zip([1, 2, 3], [4, 5, 6]))
[(1, 4), (2, 5), (3, 6)]
enumerate
>>> list(enumerate(a))
[(0, 'a'), (1, 'b'), (2, 'c')]
getattr
>>>class A(object):
> ... bar = 1
> ...
>>> a = A()
>>> getattr(a, 'bar')
1
用在自動取得attr時可能會很方便
