<p>我认为您需要通过<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.str.replace.html" rel="nofollow noreferrer">^{<cd1>}</a>和<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.str.extract.html" rel="nofollow noreferrer">^{<cd2>}</a>提取数值:</p>
<pre><code>d ={'apple': ['15.8', '356,2', '51.36', '17986,8','6.0\\tY', 'Null'],
'banana': ['27.84883300816733\\U', 'Z44.64197389840307\\Y', '?????', '13.3\\T', 'p17.6', '6.1\\Q'],
'cheese': ['27.68303400840678\\O', '39.93121897299962\\W', '???', '9.4\\J', '7.2\\K','6.0\\Y'],
'egg': ['???', '7.2\\K', '66.0\\p','23.77814972104277\\T', '2396,7', 'None']}
</code></pre>
<hr/>
<pre><code>df = pd.DataFrame(d)
print (df)
apple banana cheese egg
0 15.8 27.84883300816733\U 27.68303400840678\O ???
1 356,2 Z44.64197389840307\Y 39.93121897299962\W 7.2\K
2 51.36 ????? ??? 66.0\p
3 17986,8 13.3\T 9.4\J 23.77814972104277\T
4 6.0\tY p17.6 7.2\K 2396,7
5 Null 6.1\Q 6.0\Y None
#https://stackoverflow.com/a/28832504/2901002
pat = r"(\d+\.*\d*)"
df = df.apply(lambda x: x.str.replace(',','.').str.extract(pat, expand=False))
print (df)
apple banana cheese egg
0 15.8 27.84883300816733 27.68303400840678 NaN
1 356.2 44.64197389840307 39.93121897299962 7.2
2 51.36 NaN NaN 66.0
3 17986.8 13.3 9.4 23.77814972104277
4 6.0 17.6 7.2 2396.7
5 NaN 6.1 6.0 NaN
</code></pre>
<p>最后一种可能是铸造浮子:</p>
<pre><code>df = df.apply(lambda x: x.str.replace(',','.').str.extract(pat, expand=False)).astype(float)
print (df)
apple banana cheese egg
0 15.80 27.848833 27.683034 NaN
1 356.20 44.641974 39.931219 7.20000
2 51.36 NaN NaN 66.00000
3 17986.80 13.300000 9.400000 23.77815
4 6.00 17.600000 7.200000 2396.70000
5 NaN 6.100000 6.000000 NaN
</code></pre>