python个人学习笔记

for i in range(10) :
	Statements

del l[100:]

likes = {"color": "blue", "fruit": "apple", "pet": "dog"}
for key in likes:
    print(key)

for (key, value) in likes.items():
    print(key, value)

from dataclasses import dataclass
@dataclass
class A:
    a: int
    b: str
    c: float
li: list[A] = []
li.append(A(1, "2", 3.3))
li.append(A(2, "3", 4.4))
print(li)
# [<class '__main__.A'>, A(a=1, b='2', c=3.3), A(a=2, b='3', c=4.4)]
item = li[1]
print(item.c)
# 3.3
sorted(li, key = lambda item: item.c, reverse=True)

print("%e" %111)
x = 111
print("%e" %x)
print("%e" %(111 + 111))
print("%e %e" %(x, 111 + 111))

print('hello', end='')

print('xxx', file=sys.stderr)

>>> L = [1, 2, 3, 4, 5]
>>> print(*L)
1 2 3 4 5
>>> print(*L, sep=', ')
1, 2, 3, 4, 5
>>> print(*L, sep=' -> ')
1 -> 2 -> 3 -> 4 -> 5

it = iter([1, 2, 3])
while True:
    try:
        print(next(it))
    except StopIteration:
        break

it = iter([1, 2, 3])
for x in it:
    print(x)

import sys
import os

abspath = os.path.abspath(sys.argv[0])
dname = os.path.dirname(abspath)
os.chdir(dname)

f = open(路径, 'w')
print('Average %f' %average, file=f)

bisect.bisect_left(a, x, lo=0, hi=len(a), *, key=None)

x = pd.Series([1, 2, 3])
x.searchsorted(4)

datetime.datetime.fromtimestamp(1516332287)

from math import *
factorial(10)

os.system('命令 参数...')

import subprocess
subprocess.run(['./executable', arg1, arg2])

x = {1: 2, 4: 3, 2: 1}
sorted(x)

x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
sorted(x.items(), key=lambda item: item[1])

# https://stackoverflow.com/a/899314
import shlex
shlex.split('-o 1 --long "Some long string"')

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('-a')
parser.add_argument('-s', type=int)
parser.add_argument('-k', type=float, required=True)
parser.add_argument('-R', type=int, required=True)
parser.add_argument('--print-a', action='store_true')
# Long argument with optional value
parser.add_argument('--export-policy', nargs='?', default=False)
args = parser.parse_args()

# str or None
a = args.a
# int or None
s = args.s
# float
k = args.k
# int
R = args.R
# bool
print_a = args.print_a
# False if not in command line
# None if --export-policy
# str if --export-policy=str
export_policy = args.export_policy

import json
# 使用tab进行缩进。
json.dumps(obj, indent='\t')

import json
json.load(open(路径))

import json5
json5.load(open(路径))

from func_timeout import func_timeout, FunctionTimedOut
import os

def test():
    for _ in range(0, 2):
        os.system('for i in $(seq 1 2); do sleep 1; echo test; done')

try:
    func_timeout(1.5, test)
except FunctionTimedOut:
    print('Timeout')
except Exception as e:
    # Code to handle any other exception
    print("An error occurred: {}".format(str(e)))

from func_timeout import FunctionTimedOut
from func_timeout.StoppableThread import StoppableThread
import subprocess

def test():
    try:
        for _ in range(0, 2):
            process = subprocess.Popen(['bash', '-c', 'for i in $(seq 1 2); do sleep 1; echo test; done'])
            # We must wait with timeout, otherwise it won't respond to external exceptions.
            # https://stackoverflow.com/a/631605/13688160
            process.wait(timeout=23333333)
    except FunctionTimedOut:
        try:
            # It seems to be okay even if process.wait is completed
            process.kill()
        except NameError:
            pass

def test_timeout(seconds):
    worker = StoppableThread(target=test)
    worker.start()
    worker.join(timeout=seconds)
    if worker.is_alive():
        print('Timeout')
        worker.stop(exception=FunctionTimedOut)
        worker.join()
    print('Joined')

test_timeout(1.5)
test_timeout(4.5)