python2与python3使用差异汇总

向右看齐 2022-03-02 09:56 215阅读 0赞

*  py3 cv2模块保存中文路径

cv2.imencode('.jpg', frame)[1].tofile('中文/1.jpg') #imwrite中文乱码

*  sys.out不可同时出现在不同文件，否则[报错][Link 1]‘ValueError: I/O operation on closed file.’

if int(sys.version[0])==3:
        sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8') #中文输出

*  py3环境json.loads(requests.body)报错：[the JSON object must be str, not 'bytes'][the JSON object must be str_ not _bytes]

json.loads(str(self.request.body, encoding='utf-8'))

*  py3中文print异常：UnicodeEncodeError: 'ascii' codec can't encode characters in position 7-10: ordinal not in range(128)

import io, sys
    if int(sys.version[0])==3:
        sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8')

*  文本读取，py3中不适用utf-8时，报错：UnicodeEncodeError: '**gbk**' codec can't encode character: **illegal multibyte sequence**

with open(txt, 'r') as f:   #py2
      buffs = f.realines()
    
    with open(txt, 'r', encoding='utf-8') as f: #py3
      buffs = f.readlines()

*  文件读取， py3 报错 UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte

with open(imagePath, 'r') as f:  #py2
    	imageBin = f.read()
    
    with open(imagePath, 'rb') as f:  #py3
    	imageBin = f.read()

*  base64.b64encode(字符串)，相关错误：[ a bytes-like object is required][a bytes-like object is required]

key='tmp'
    if int(sys.version_info[0]) == 3:
        headers={'Authorization':'Basic' + base64.b64encode(key.encode()).decode()}
    else:
        headers = {'Authorization': 'Basic' + base64.b64encode(key)}

*  类继承

class mask_rcnn_outputs(nn.Module):
        def __init__(self, dim_in):
            super(mask_rcnn_outputs, self).__init__()   #python2
    
    
    class mask_rcnn_outputs(nn.Module):
        def __init__(self, dim_in):
            super().__init__()              #python3

*  模块加载

import sys
    if int(sys.version[0])==2:
        import cPickle
        import json
        import urllib
    else:
        import pickle as cPickle
        import simplejson as json
        import urllib.request as urllib

*  [python3中is not JSON serializable][python3_is not JSON serializable]

方法1：转换编码为unicode
     Either transform into Unicode (json.dumps(x.decode("utf-8"))), 
     or into an integer array (json.dumps(list(x))).
    
    方法2：pip3 install simplejson
    
    import simplejson as json

*  除法运算差异，这也是py2转py3常遇到的问题

>>> 1/2        #py2
    0
    
    
    >>> 1/2        #py3
    0.5
    >>> 1//2
    0

参考文献：

1.  [TypeError: a bytes-like object is required, not 'str' when writing to a file in Python3][a bytes-like object is required]
2.  ['urllib' object has no attribute 'urlretrieve'][urllib_ object has no attribute _urlretrieve]

[Link 1]: https://stackoverflow.com/questions/40924256/python-i-o-operation-on-a-closed-file-why-the-error-code-below
[the JSON object must be str_ not _bytes]: https://stackoverflow.com/questions/42683478/typeerror-the-json-object-must-be-str-not-bytes
[a bytes-like object is required]: https://stackoverflow.com/questions/33054527/typeerror-a-bytes-like-object-is-required-not-str-when-writing-to-a-file-in
[python3_is not JSON serializable]: https://stackoverflow.com/questions/36212905/python-3-is-not-json-serializable
[urllib_ object has no attribute _urlretrieve]: https://stackoverflow.com/questions/17960942/attributeerror-module-object-has-no-attribute-urlretrieve