python基础知识 | marstau's blog

Installation

CentOS 7.4More

curl -L -o python-3.8.1.tgz https://www.python.org/ftp/python/3.8.1/python-3.8.1.tgz
tar -zxvf python-3.8.1.tgz
cd python-3.8.1
./configure --prefix=/usr/local/python3
make
make install
ln -s /usr/local/python3/bin/python3 /usr/local/bin/python3
ln -s /usr/local/python3/bin/pip3 /usr/local/bin/pip3

Commands

sudo rm -R /System/Library/Frameworks/python.framework/Versions/2.7 # mac下卸载系统自带python2.7
pip3 install -r requirements.txt #批量安装txt文件中的package

语法

(path, filename) = os.path.split("D:/test/test.py") #提取目录文件名
(filename, extension) = os.path.splitext("D:/test/test.py") #提取文件名和后缀 (D:/test/test, .py)

file_name = os.path.basename("D:/test/test1.py") #提取文件名 test1.py
text1 = os.path.splitext(file_name)[0]  #提取文件名不含后缀 test1

demjson.encode(skillValue) #数组转json字符串
if s is not None:

遍历数组

for idx in range(0, len(array)):
    print(idx)

多线程More

多进程More 变量共享

FAQ

copy files with structure.

# destPathName = "a/b.txt"
os.makedirs(os.path.dirname(destPathName), exist_ok=True)
shutil.copy(srcPathName, destPathName)

setup.py

init.py

通常__init__.py 文件为空，但是我们还可以为它增加其他的功能。我们在导入一个包时，实际上是导入了它的__init__.py文件这样我们可以在__init__.py文件中批量导入我们所需要的模块，而不再需要一个一个的导入。

缩进More

Python的函数体使用缩进来表示，函数体至少应当保持一个空格的缩进。当缩进结束的时候，表示函数体结束。

sys.path.appendMore

对于模块和自己写的程序不在同一个目录下，可以把模块的路径通过sys.path.append(路径)添加到程序中。

import sys
sys.path.append('src/mugen/parser')

`import('pkg_resources').declare_namespace(name)`More More2

暂停

import signal

def signal_handler(signal_number, frame):
    print "Proceed ..."

signal.signal(signal.SIGINT, signal_handler)
signal.pause()

写日志

import logging
logging.basicConfig(level=logging.DEBUG,#控制台打印的日志级别
                    filename='new.log',
                    filemode='a',##模式，有w和a，w就是写模式，每次都会重新写日志，覆盖之前的日志
                    #a是追加模式，默认如果不写的话，就是追加模式
                    format=
                    '%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s' #日志格式
                    )
logging.info("print to file")

get current project path

os.path.dirname(os.path.realpath(__file__))

遍历目录

def LoopDirectory(root_dir, out_file_name, includes, excludes, extras = None):
    for root, dirs, files in os.walk(root_dir, topdown=True):
        dirs[:] = [d for d in dirs if d not in excludes]

        for pat in includes:
            for f in fnmatch.filter(files, pat):
                file_path = os.path.join(root, f)
                file = open(file_path, "rb")
                
                s = file.read()

                file.close()

switchMore

def foo(var,x):
    return {
            'a': lambda x: x+1,
            'b': lambda x: x+2,
            'c': lambda x: x+3, 
    }[var](x)

python多版本管理

pyenv - mac

python launcherMore

py -3 -m pip install package_name
py -2 test.py # 使用python2.x来执行test.py
py -3.5 test.py # 使用python3.5来执行test.py

代码中使用:

#! python3.7
# -*- coding:utf-8 -*-
import sys
import time

print(sys.version)
time.sleep(3600)

根据第一行的声明来选择使用哪个版本py get_version.py

版本号判断

if sys.version_info[:2] >= (3, 0):
    raise RuntimeError('Less than python 3.0 is required')

Error

`no module named ‘_ctypes’`More

Solution:

yum install libffi-devel

然后重新安装python, make && make install.

multiprocessing AttributeError: ‘ForkAwareLocal’ object has no attribute ‘connectMore

max_jobs_running = 8
jobs_running = 0
runningJobs = []
for p in p_l:
    p.start()
    jobs_running += 1
    if jobs_running >= max_jobs_running:
        while jobs_running >= max_jobs_running:
            jobs_running = 0
            for p in p_l:
                jobs_running += p.is_alive()

Fatal error in launcher: Unable to create process usingMore

python3 -m pip install --upgrade pip
python3  -m pip install --upgrade --force-reinstall pip

`/Users/user/.pyenv/shims/python: line 21: /usr/local/Cellar/pyenv/1.2.20/libexec/pyenv: No such file or directory`More

pyenv rehash

pip安装报错`Microsoft Visual C++ 14.0 is required . Get it with “Microsoft Visual C++ Build Tools”`More

error: Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools": http://landinghub.visualstudio.com/visual-cpp-build-tools

Solution:

下载对应whl文件<http://www.lfd.uci.edu/~gohlke/pythonlibs/#wordcloud>

导入本地package

sys.path.append("./library/ccxt/python")
import ccxt

执行shell命令

sshDir = "~/.ssh"
subprocess.run(f"chmod 755 {sshDir}/*", shell=True)

map类型判断

isinstance(jmsgs, dict)

from collections.abc import Mapping
if isinstance(any_object, Mapping):

bytes类型判断

isinstance(data, (bytes, bytearray))

字符串格式化More

+       右对齐；正数前加正好，负数前加负号；
-        左对齐；正数前无符号，负数前加负号；
空格    右对齐；正数前加空格，负数前加负号；
0        右对齐；正数前无符号，负数前加负号；用0填充空白处

print("%(name)+10s————————%(age)-10d————————"%{'name':'xx','age':20})

结果:
        xx————————20        ————————

同时运行多个WebSocketApp长链接

def worker1():
    open_socket1()

def worker2():
    open_socket2()


threads = []
t = threading.Thread(target=worker1)
threads.append(t)
t.start()

t = threading.Thread(target=worker2)
threads.append(t)
t.start()

让电脑发出声音

os.system('say "hello"')

字符串查找

import re
a = 'abcABC123'
b = re.search('[A-Z](?=[^A-Z]*)',a)
print(b.span(),a[b.span()[0]])

查找所有匹配索引

s = 'a good boy, a good girl. a bad man.'
f = re.finditer('good',s)
print(f)
for i in f:
    print(i)
    print(i.span())

import子目录的python脚本

目录结构如下

|-- main.py
|-- test
      |-- test1.py

method1:

sys.path.append("test")
import test1

method2: test目录新建__init__.py

from test import test1

Error

ftp上传报错`创建目录发生错误: <paramiko.ChannelFile from <paramiko.Channel 2 (EOF received) (open) window=2097152 -> <paramiko.Transport at 0xf2140148 (cipher aes128-ctr, 128 bits) (active; 1 open channel(s))>>>`

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