如何base64编码和解码python pandas中的一列？

Question

我读了这篇文章

编码数据帧

但我不想加密数据帧，只需将其转换为 base 64。我将回车分隔的单词列表导入到数据帧中：

words = pd.read_table("sampleText.txt",names=['word'], header=None)
words.head()

那给

    word
0   difference
1   where
2   mc
3   is
4   the

然后

words['words_encoded'] = map(lambda x: x.encode('base64','strict'), words['word'])
print (words)

给

                word                   words_encoded
0         difference  <map object at 0x7fad3e89e410>
1              where  <map object at 0x7fad3e89e410>
2                 mc  <map object at 0x7fad3e89e410>
3                 is  <map object at 0x7fad3e89e410>
4                the  <map object at 0x7fad3e89e410>
...              ...                             ...
999995  distribution  <map object at 0x7fad3e89e410>
999996            in  <map object at 0x7fad3e89e410>
999997      scenario  <map object at 0x7fad3e89e410>
999998          less  <map object at 0x7fad3e89e410>
999999          land  <map object at 0x7fad3e89e410>

[1000000 rows x 2 columns]

我不明白为什么我的编码列指的是地图对象而不是实际数据，所以我尝试了：

b64words = words.word.str.encode('base64')
print(b64words)

给

0        NaN
1        NaN
2        NaN
3        NaN
4        NaN
          ..
999995   NaN
999996   NaN
999997   NaN
999998   NaN
999999   NaN
Name: word, Length: 1000000, dtype: float64

好，

这让我很失望，所以我阅读了上面的链接答案并尝试

import base64
def encode(text):
    return base64.b64encode(text)
words['Encoded_Column'] = [encode(x) for x in words]

但得到

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-89-8cf5a6f1f3a9> in <module>
      2 def encode(text):
      3     return base64.b64encode(text)
----> 4 words['Encoded_Column'] = [encode(x) for x in words]

<ipython-input-89-8cf5a6f1f3a9> in <listcomp>(.0)
      2 def encode(text):
      3     return base64.b64encode(text)
----> 4 words['Encoded_Column'] = [encode(x) for x in words]

<ipython-input-89-8cf5a6f1f3a9> in encode(text)
      1 import base64
      2 def encode(text):
----> 3     return base64.b64encode(text)
      4 words['Encoded_Column'] = [encode(x) for x in words]

~/miniconda3/envs/p37cu10.2PyTo/lib/python3.7/base64.py in b64encode(s, altchars)
     56     application to e.g. generate url or filesystem safe Base64 strings.
     57     """
---> 58     encoded = binascii.b2a_base64(s, newline=False)
     59     if altchars is not None:
     60         assert len(altchars) == 2, repr(altchars)

TypeError: a bytes-like object is required, not 'str'

所以我尝试转换为像这样的对象的字节：

import base64
def encode(text):
    btext = text.str.encode('utf-8')
    return base64.b64encode(btext)
words['Encoded_Column'] = [encode(x) for x in words]

但得到

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-90-46db6d3688ba> in <module>
      3     btext = text.str.encode('utf-8')
      4     return base64.b64encode(btext)
----> 5 words['Encoded_Column'] = [encode(x) for x in words]

<ipython-input-90-46db6d3688ba> in <listcomp>(.0)
      3     btext = text.str.encode('utf-8')
      4     return base64.b64encode(btext)
----> 5 words['Encoded_Column'] = [encode(x) for x in words]

<ipython-input-90-46db6d3688ba> in encode(text)
      1 import base64
      2 def encode(text):
----> 3     btext = text.str.encode('utf-8')
      4     return base64.b64encode(btext)
      5 words['Encoded_Column'] = [encode(x) for x in words]

AttributeError: 'str' object has no attribute 'str'

在这个C 示例中，他们也首先转换为字节字符串，然后转换为 base64 之类的，但我无法在 Python 中完成这个简单的任务。 我非常感谢一个头脑清晰的人可以提供的任何帮助。

Answer 1

map返回迭代，而不是一个列表，因此pandas简单地在新形成的“words_encoded”列它分配给所有时隙。 同样，如果您执行words['all_ones'] = 1 ， pandas会在该列下分配 1。

其次，“base64”不是字符串的编解码器，它适用于bytes 。 您必须选择一种文本编码，然后对其进行编码。 所以，

words['word_encoded'] = words.word.str.encode(
    'utf-8', 'strict').str.encode('base64')

除了这个编码器在 base64 字符串的末尾放了一个“\\n”，我觉得这很奇怪。 相反，您可以执行以下操作之一

words['word_encoded'] = words.word.str.encode(
    'utf-8', 'strict').apply(
         base64.b64encode)

# or 

words['word_encoded'] = [base64.b64encode(x.encode('utf-8', 'strict'))
    for x in words.word]

我个人认为第一个更像是“熊猫”，因为它直接生成系列而没有中间列表。

行动中的解决方案

>>> import base64
>>> import pandas as pd
>>> words = pd.read_table("sampleText.txt",names=['word'], header=None)
__main__:1: FutureWarning: read_table is deprecated, use read_csv instead, passing sep='\t'.
>>> words['word_encoded'] = words.word.str.encode(
...     'utf-8', 'strict').str.encode('base64')
>>> 
>>> words
         word           word_encoded
0  difference  b'ZGlmZmVyZW5jZQ==\n'
1       where          b'd2hlcmU=\n'
2          mc              b'bWM=\n'
3          is              b'aXM=\n'
4         the              b'dGhl\n'
>>> 
>>> words['word_encoded'] = words.word.str.encode(
...     'utf-8', 'strict').apply(
...          base64.b64encode)
>>> 
>>> words
         word         word_encoded
0  difference  b'ZGlmZmVyZW5jZQ=='
1       where          b'd2hlcmU='
2          mc              b'bWM='
3          is              b'aXM='
4         the              b'dGhl'
>>> 
>>> words['word_encoded'] = [base64.b64encode(x.encode('utf-8', 'strict'))
...     for x in words.word]
>>> 
>>> words
         word         word_encoded
0  difference  b'ZGlmZmVyZW5jZQ=='
1       where          b'd2hlcmU='
2          mc              b'bWM='
3          is              b'aXM='
4         the              b'dGhl'

Answer 2

只需从函数体中删除 .str 即可。 真实代码：

import base64


def encode(text):
    btext = text.encode('utf-8')
    return base64.b64encode(btext)


words = {'1': 1, '2': 2, '3': 3, 'asdasd': 4}
words['Encoded_Column'] = [encode(x) for x in words]
print(words)

它的输出是：

{'1': 1, '2': 2, '3': 3, 'asdasd': 4, 'Encoded_Column': [b'MQ==', b'Mg==', b'Mw==', b'YXNkYXNk']}