Python问题总结(三)

每篇10个问题.
Python问题总结(一)
Python问题总结(二)

1 opencv尺寸报错

1.0 Problem

cv2.error: /build/opencv-L2vuMj/opencv-3.2.0+dfsg/modules/highgui/src/window.cpp:304: error: (-215) size.width>0 && size.height>0 in function imshow

1.2 Reason

opencv获取的视频流为空.

1.3 Solve

重新检查是否有输入视频流.

2 socket通信

2.1 Problem

Traceback (most recent call last):
  File "socket_server.py", line 24, in 
    _server.server_test()
  File "socket_server.py", line 19, in server_test
    c.send("I am xin daqi")
TypeError: a bytes-like object is required, not 'str'

2.2 Reason

send字节数据,不是str.

2.3 Solve

import socket
c = socket.socket()
# snap
c.send(bytes("I am xin daqi", encoding='utf-8'))

3 utf-8编码错误

• Problem

UnicodeDecodeError: 'utf-8' codec can't decode byte 0x80 in position 8: invalid start byte

• Reason
  *.py文件开头没有引入utf-8.
• Resolve
  (1) *.py文件开始加入utf-8.

#-*-coding:utf-8-*-

(2) 字节转字符串
bytes使用encode进行编码转换为str

bytes.decode('utf8')
bytes.decode('utf-8')

(3) 字符串转字节
str编码为bytes

str.encode('utf-8')
print("你好").encode("utf-8")

4 supervisor通信问题

4.1 Error1

unix:///var/run/supervisor.sock no such file

• Reason
  没有supervisor.sock
• Solve
  新建supervisor.sock文件,修改权限sudo chmod 777 supervisor.sock

4.2 Error2

error: , [Errno 111] Connection refused: file: /usr/lib/python2.7/socket.py line: 228

unix:///var/run/supervisor.sock refused connection

• Reason
  未启动supervisord
• Solve
  手动启动supervisord
sudo supervisord -c /etc/supervisor/supervisord.conf

4.3 Error3

Error: Could not determine IP address for hostname ai-lab-gpu, please try setting an explicit IP address in the "port" setting of your [inet_http_server] section.  For example, instead of "port = 9001", try "port = 127.0.0.1:9001."
For help, use /usr/bin/supervisord -h

Error: Cannot open an HTTP server: socket.error reported errno.EADDRNOTAVAIL (99)

compiled with version: 5.4.0 20160609 on 28 September 2018 15:49:44
os: Linux-4.4.0-104-generic #127-Ubuntu SMP Mon Dec 11 12:16:42 UTC 2017
nodename: ai-lab-gpu
machine: x86_64
clock source: unix
pcre jit disabled
detected number of CPU cores: 16
current working directory: /home/SP-in-AI/xindq/couplets
detected binary path: /usr/bin/uwsgi-core
*** WARNING: you are running uWSGI without its master process manager ***
your processes number limit is 257559
your memory page size is 4096 bytes
detected max file descriptor number: 1024
lock engine: pthread robust mutexes
thunder lock: disabled (you can enable it with --thunder-lock)
bind(): Cannot assign requested address [core/socket.c line 769]

• Reason
  socket设置错误
• Solve
  使用http配置IP
  http=127.0.0.1:8080

5 cuDNN与CUDA配置

• Problem

libcublas.so.9.0: cannot open shared object file: No such file or directory

• Reason
  未配置环境变量
• Solve

export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/usr/local/cuda/lib64"
export CUDA_HOME=/usr/local/cuda

详见博客:服务器(Linux)部署cuDNN

6 scrapy crawl 找不到关键字

• Problem

Traceback (most recent call last):
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/spiderloader.py", line 69, in load
    return self._spiders[spider_name]
KeyError: 'baidu_search'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/xdq/.local/bin/scrapy", line 11, in 
    sys.exit(execute())
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/cmdline.py", line 150, in execute
    _run_print_help(parser, _run_command, cmd, args, opts)
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/cmdline.py", line 90, in _run_print_help
    func(*a, **kw)
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/cmdline.py", line 157, in _run_command
    cmd.run(args, opts)
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/commands/crawl.py", line 57, in run
    self.crawler_process.crawl(spname, **opts.spargs)
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/crawler.py", line 170, in crawl
    crawler = self.create_crawler(crawler_or_spidercls)
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/crawler.py", line 198, in create_crawler
    return self._create_crawler(crawler_or_spidercls)
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/crawler.py", line 202, in _create_crawler
    spidercls = self.spider_loader.load(spidercls)
  File "/home/xdq/.local/lib/python3.6/site-packages/scrapy/spiderloader.py", line 71, in load
    raise KeyError("Spider not found: {}".format(spider_name))
KeyError: 'Spider not found: baidu_search'

• Reason
  缺少配置文件.
• Solve
  使用命令新建完整文件.

cd scrapy_html
scrapy startproject firstscrapy

文件结构

|-- scrapy_html
|   `-- firstscrapy
|       |-- firstscrapy
|       |   |-- __init__.py
|       |   |-- __pycache__
|       |   |   |-- __init__.cpython-36.pyc
|       |   |   `-- settings.cpython-36.pyc
|       |   |-- items.py
|       |   |-- middlewares.py
|       |   |-- pipelines.py
|       |   |-- settings.py
|       |   `-- spiders
|       |       |-- __init__.py
|       |       |-- __pycache__       
|       `-- scrapy.cfg

7 字符串去除标点符号

• Demo

string = "E 我是天蓝蓝,你?是 谁?" 
# string = string.encode("utf8")
# string = re.sub("[\s+\.\!\/_,$%^*(+\"\']+|[+——！，。？、~@#￥%……&*（）]+".encode("utf8"), "".encode("utf8"),string)
string = re.sub("[\s+\.\!\/_,$?%^*(+\"\']+|[+——！，。？、~@#￥%……&*（）]+","",string)
string = string[1:]
print("cut symbol: {}".format(string))

• Reslut

cut symbol: 我是天蓝蓝你是谁

8 Scrapy连续爬取出现问题

• Problem

 DEBUG: Filtered offsite request to 'www2.soopat.com': 

• Reason
  allow_domains设置错误
• Solve

allowed_domains = ["soopat.com"]

9 flask request传输数据为空报错

• Problem

 if "Image" in request.json:
TypeError: argument of type 'NoneType' is not iterable

• Reason
  上传的json文件为空,导致数据为空,不可遍历
• Solve
  先做数据是否存在判断在做数据是否符合格式判断;

if reqeust.json and "Image" in request.json:
	upload_data = request.json["Image"]

详细讲解参考博客第二节:Flask post,get请求request获取json,form,file参数

10 python多版本运行程序

python2.x和python3.x共存于操作系统，若没有使用Anaconda或Virtualenv管理环境，使用对应版本的python可使用如下命令：

python2.7 run.py
python3.5 run.py
python3.6 run.py
python3.7 run.py

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[参考文献]
[1]https://www.cnblogs.com/xiaojianliu/p/9443874.html
[2]https://www.cnblogs.com/aylin/p/5572104.html
[3]https://blog.csdn.net/ksws0292756/article/details/80034086
[4]https://blog.csdn.net/Xin_101/article/details/87165132

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