python学习笔记

本来不想看python了, 但是gcc编译环境的各种版本兼容性问题, 放弃吧.

只是想用wxWedgits... 算了, 直接用wxPython好了.

20190813 公司给了一台CentOS7.2.1511, 从原码开始安装, 下载到/tmp下

xz -d Python-3.7.4.tar.xz
tar -xvf Python-3.7.4.tar

安装一些依赖库
yum -y install bzip2-devel ncurses-devel db4-devel gdbm gdbm-devel libpcap-devel xz xz-devel libffi-devel lzma sqlite sqlite-devel tk tk-devel libuuid-devel readline-devel zlib-devel
 

cd Python-3.7.4
./configure --prefix=/usr/local/python3.7 --enable-optimizations

make
make install

中途有失败 make clean掉, 解决重新来.或者从头来.
https://www.code-learner.com/how-to-compile-and-install-python3-from-source-code-in-centos/
https://www.linuxidc.com/Linux/2018-01/150564.htm
https://blog.csdn.net/pengjunlee/article/details/89100730

pip 更换源

https://www.cnblogs.com/lpl521/p/6778048.html

mkdir ~/.pip
cd ~/.pip
touch pip.conf
vi pip.conf
---------------------------------
[global]
index-url = http://mirrors.xxxxxx/pypi/simple/
[install]
trusted-host = mirrors.xxxxxx


/////////////////////////////////////////////////////////////////////////////////////////////////////

可以使用内网镜像来安装
pip install -i http://mirrors.xxxxxxx/pypi/simple xxxpackage --trusted-host mirrors.xxxxxxx

windows下,配置pip.ini 文件内容如下：
https://jingyan.baidu.com/article/3d69c55127775af0cf02d79e.html
--------------------------------------------------------------
[global]
index-url = http://mirrors.xxxxx
[install]
trusted-host=mirrors.xxxx
--------------------------------------------------------------
pip install xxxpackage

python doc, 有中文, 讲解最全

https://docs.python.org/zh-cn/3/library/python.html

https://docs.python.org/zh-cn/3/library/builtins.html

pyinstaller

https://pythonhosted.org/PyInstaller/installation.html

MysqlPython

https://pypi.org/project/MySQL-python/

wxpython

https://wiki.wxpython.org/Getting%20Started

C/C++ mysql

https://www.cnblogs.com/cy163/archive/2009/10/03/1577812.html

https://www.cnblogs.com/wunaozai/p/4528394.html

pip国内镜像, 清华大学的最快. 超过阿里云

https://www.cnblogs.com/biglittleant/p/6944180.html

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opencv python 安装

官方从源头安装
https://docs.opencv.org/4.1.0/d5/de5/tutorial_py_setup_in_windows.html

没意见, 但是会碰到各种问题.

简单安装
https://qiita.com/cointoss1973/items/92d82f9accb239a276a0
日本人写的简洁明了

pip install opencv-python
pip install opencv-contrib-python

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点滴:

python 与json

https://www.geeksforgeeks.org/json-formatting-python/
https://docs.python.org/3/library/json.html


Functions
json.dump(obj, fileObj): Serializes obj as a JSON formatted stream to fileObj.
json.dumps(obj) : Serializes obj as JSON formatted string.
json.load(JSONfile) : De-serializes JSONfile to a Python object.
json.loads(JSONfile) : De-serializes JSONfile(type: string) to a Python object.Classes

JSONEncoder: An encoder class to convert Python objects to JSON format.
JSONDecoder: A decoder class to convert JSON format file into Python obj.
The conversions are based on this conversion table.

--------------------------------------------------------------
Encoding
We will be using dump(), dumps() and JSON.Encoder class.

#Code will run in Python 3 

from io import StringIO 
import json 

fileObj = StringIO() 
json.dump(["Hello", "Geeks"], fileObj) 
print("Using json.dump(): "+str(fileObj.getvalue())) 

class TypeEncoder(json.JSONEncoder): 
    def default(self, obj): 
        if isinstance(obj, type): 
            return str(obj) 

print("Using json.dumps(): "+str(json.dumps(type(str), cls=TypeEncoder))) 
print("Using json.JSONEncoder().encode"+
    str(TypeEncoder().encode(type(list)))) 
print("Using json.JSONEncoder().iterencode"+
    str(list(TypeEncoder().iterencode(type(dict))))) 

Output:
////////////////////////////////////////////////////
Using json.dump(): ["Hello", "Geeks"]
Using json.dumps(): ""
Using json.JSONEncoder().encode""
Using json.JSONEncoder().iterencode['""']

////////////////////////////////////////////////////


Decoding
We will be using load(), loads() and JSON.Decoder class.

#Code will run in Python 3 

from io import StringIO 
import json 

fileObj = StringIO('["Geeks for Geeks"]') 
print("Using json.load(): "+str(json.load(fileObj))) 
print("Using json.loads(): "+str(json.loads('{"Geeks": 1, "for": 2, "Geeks": 3}'))) 
print("Using json.JSONDecoder().decode(): " +
    str(json.JSONDecoder().decode('{"Geeks": 1, "for": 2, "Geeks": 3}'))) 
print("Using json.JSONDecoder().raw_decode(): " +
    str(json.JSONDecoder().raw_decode('{"Geeks": 1, "for": 2, "Geeks": 3}'))) 

output:
////////////////////////////////////////////////////////////////////////////////////
Using json.load(): ['Geeks for Geeks']
Using json.loads(): {'for': 2, 'Geeks': 3}
Using json.JSONDecoder().decode(): {'for': 2, 'Geeks': 3}
Using json.JSONDecoder().raw_decode(): ({'for': 2, 'Geeks': 3}, 34)
///////////////////////////////////////////////////////////////////////////////////

这个也不错! 比较全面

https://realpython.com/python-json/

Encoders and Decoders

class json.JSONDecoder(*, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, strict=True, object_pairs_hook=None)

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

python 与 shell 非常好.(python3以后不再支持commands)

import subprocess

p = subprocess.Popen(["echo", "hello world"], stdout=subprocess.PIPE)

print(p.communicate())

>>>('hello world', None)

https://www.pythonforbeginners.com/os/subprocess-for-system-administrators

from subprocess import Popen, PIPE
p1 = Popen(["dmesg"], stdout=PIPE)
print (p1.communicate()[0])


/////////////////////////////////////////////////////////
import subprocess
import json

cmd = '''sh ./abc.sh'''

p1 = subprocess.Popen(cmd, stdout=subprocess.PIPE)
output = p1.communicate()[0]
print(type(output))
jstr = output.decode(encoding='utf-8')
jObj = json.loads(jstr)

jstr2 = json.dumps(jObj, indent=4)
print(jstr2)

/////////////////////////////////////////////////////////////////////////////////////////////////////

python的对象类型与序列化类型

https://realpython.com/python-json/

c = b.decode(encoding='utf-8')

type(c)

<class 'str'>

当一个print打印出来为 b'xxxxxx'的时候, 就可以decode一下, 成为string打印

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python的判断

a==b 是值相等判断, a is b 是地址相同判断

a=None, 给a赋值None之后, a==None, a is None -->True

b=None, a==b, a is b --->True

如果直接判断 a == c , a is c就会报错

NameError: name 'c' is not defined

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python中接种换行写法

第一种：

x0 = '<?xml version="1.0"?>' \
     '<ol>' \
     '  <li><a href="/python">Python</a></li>' \
     '  <li><a href="/ruby">Ruby</a></li>' \
     '</ol>'

第二种：

x1 = '<?xml version="1.0"?> \
<ol> \
    <li><a href="/python">Python</a></li> \
    <li><a href="/ruby">Ruby</a></li> \
</ol>'

第三种：

x2 = ('<?xml version="1.0"?>'
      '<ol>'
      ' <li><a href="/python">Python</a></li>'
      ' <li><a href="/ruby">Ruby</a></li>'
      '</ol>')

第四种：

x3 = '''<?xml version="1.0"?>
<ol>
    <li><a href="/python">Python</a></li>
    <li><a href="/ruby">Ruby</a></li>
</ol>'''

https://www.cnblogs.com/Jimc/p/9596482.html

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python执行shell脚本

抄来的

# coding=utf-8 //设置文本格式
import os //导入os方法
print('hello')
n=os.system('/home/csliyb/kjqy_xcy/bdse-tour-dp-2.1/bin/test.sh') //调用shell脚本
print '执行完毕'

下面这个有几种方式

https://www.cnblogs.com/hei-hei-hei/p/7216434.html

posted @ 2019-06-12 17:56 multitude 阅读(232) 评论(0) 编辑收藏举报

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