Pandas DataFrame 删除具有特定字符的字符串

Question

我有一个带有大量文本数据的 pandas DataFrame。我想删除所有以“*”标记开头的行。因此，我尝试了一个小例子，如下所示。

string1 = '''* This needs to be gone
But this line should stay
*remove 
* this too
End'''

string2 = '''* This needs to be gone
But this line should stay
*remove 
* this too
End'''

df = pd.DataFrame({'a':[string1,string2]})
df['a'] = df['a'].map(lambda a: (re.sub(r'(?m)^\*.*\n?', '', a, flags=re.MULTILINE)))

它可以完美地完成这项工作。但是，当我将相同的功能应用于原始 DataFrame 时，它​​不起作用。你能帮我找出问题吗？

df2['NewsText'] = df2['NewsText'].map(lambda a: (re.sub(r'(?m)^\*.*\n?', '', a, flags=re.MULTILINE)))
df2.head()

Pease see the attached image of my original DataFrame

Answer 1

鉴于您的示例数据

• .str.split('\n') 创建每个部分的列表
• .apply(lambda x: '\n'.join([y for y in x if '*' not in y])) 使用列表推导来删除带有 * 的每个句子，然后将其连接回字符串。
  • 您可以通过' '.join 或''.join 加入
• .apply(lambda x: [y for y in x if '*' not in y]) 如果你想要一个列表而不是一个长字符串。

|    | a                         |
|---:|:--------------------------|
|  0 | * This needs to be gone   |
|    | But this line should stay |
|    | *remove                   |
|    | * this too                |
|    | End                       |
|  1 | * This needs to be gone   |
|    | But this line should stay |
|    | *remove                   |
|    | * this too                |
|    | End                       |

# remove sections with '*'
df['a'] = df['a'].str.split('\n').apply(lambda x: '\n'.join([y for y in x if '*' not in y]))

# final
|    | a                         |
|---:|:--------------------------|
|  0 | But this line should stay |
|    | End                       |
|  1 | But this line should stay |
|    | End                       |