+python+pip安装の変更点

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+python+pip安装へ行く。
+python+pip安装の差分を削除
#author("2022-06-07T08:41:14+08:00","default:Admin","Admin")
#author("2022-06-07T15:20:55+08:00","default:Admin","Admin")
[[Python]]

&color(red){※This article is based on Python 3.7.3};

#contents

* pip安装第三方库 [#r75ed322]

pip install scikit-learn		#下载scikit-learn

只要在下载软件的后面加上==号，写入版本号即可！
 pip install 软件名==版本号

# 下载scikit-learn的0.18.0版本
 pip install scikit-learn==0.18.0

# 以管理者身份下载scikit-learn的0.18.0版本
 pip install --user-v scikit-learn==0.18.0

#将库中的python模块用作脚本去运行安装scikit-learn
 python -m pip install scikit-learn

* 安装pip [#g96cc3cf]

安装python3.x的pip

 sudo apt-get install python3-pip

* 问题 [#g05c16b9]

** pip无法升级 [#d5b36b31]

报错：

#codeprettify{{
Collecting pip
  Using cached https://files.pythonhosted.org/packages/52/e1/06c018197d8151383f66ebf6979d951995cf495629fc54149491f5d157d0/pip-21.2.4.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "c:\users\tzzha\appdata\local\temp\pip-build-nzbfrv\pip\setup.py", line 7
        def read(rel_path: str) -> str:
                         ^
    SyntaxError: invalid syntax

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in c:\users\tzzha\appdata\local\temp\pip-build-nzbfrv\pip\
You are using pip version 8.1.2, however version 21.2.4 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.
}}

解决

 python -m pip install --user --upgrade pip==20.2.4  #(换成你想要的版本编号)

** ssl certificate [#xaf99a28]

#codeprettify{{
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/virtualenv/

Could not fetch URL https://pypi.org/simple/virtualenv/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/virtualenv/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping
}}

*** 解决方法 [#s7babc1c]

先安装 virtualenv 
 pip install virtualenv -i http://mirrors.aliyun.com/pypi/simple --trusted-host mirrors.aliyun.com

** Ubuntu urllib2.URLError:<urlopen error unknown url type:https> [#e5b73d1d]

*** 原因 [#g9b3b7ec]

是因为 Python 不支持 openssl 造成的，需要重新编译安装 python

参考官网
 Note HTTPS support is only available if Python was compiled with SSL support (through the ssl module). 
https://docs.python.org/3/library/http.client.html

*** 解决方法 [#s7babc1c]

在安装python之前，需要先安装 openssl

 ./config
 sudo make
 sudo make install

安装 python 时如下配置之后安装
 ./configure --prefix=/root/python38 --with-openssl=/root/openssl-1.1.0l --enable-shared
 make
 make install

注意：/root/openssl-1.1.0l路径为openssl官网下载的源码包解压后的文件夹路径

安装后的验证：启动 python 命令行然后输入下面

 import ssl

** ubuntu WARNING: Download failure <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1131)> [#q5c18c48]

*** 解决方法 [#ma9bff2d]

 sudo update-ca-certificates --fresh
 export SSL_CERT_DIR=/etc/ssl/certs

** AttributeError: module 'serial' has no attribute 'serial_for_url' [#p00b6ce7]

*** 解决方法 [#gbf4ae42]
许多人从网上找到串口代码后，直接安装了serial，无法运行，然后又安装pyserial，出现上述问题，本文给出解决建议。 

如果你是按上述情况操作的，即使卸载了serial也无济于事，必须将二者同时卸载，然后单独安装最新版本的pyserial库。

#hr();
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pip安装 の変更点

pip安装の変更点
