pandas 波浪号在python数据框中签名
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Tilde sign in python dataframe
提问by Nirojan Selvanathan
Im new to python and came across a code snippet.
我是 Python 新手，遇到了一个代码片段。
df = df[~df['InvoiceNo'].str.contains('C')]
Would be much obliged if I could know whats the tilde signs usage in this context ?
如果我能知道在这种情况下波浪号的用法是什么，我会非常感激吗？
采纳答案by jezrael
It means bitwise not, inversing boolean mask - Falses to Trues and Trues to Falses.
这意味着按位不，反转布尔掩码 - Falses 到Trues 和 Trues 到Falses。
Sample:
样本：
df = pd.DataFrame({'InvoiceNo': ['aaC','ff','lC'],
'a':[1,2,5]})
print (df)
InvoiceNo a
0 aaC 1
1 ff 2
2 lC 5
#check if column contains C
print (df['InvoiceNo'].str.contains('C'))
0 True
1 False
2 True
Name: InvoiceNo, dtype: bool
#inversing mask
print (~df['InvoiceNo'].str.contains('C'))
0 False
1 True
2 False
Name: InvoiceNo, dtype: bool
Filter by boolean indexing:
过滤条件boolean indexing：
df = df[~df['InvoiceNo'].str.contains('C')]
print (df)
InvoiceNo a
1 ff 2
So output is all rows of DataFrame, which not contains Cin column InvoiceNo.
所以输出是DataFrame的所有行，C列中不包含InvoiceNo。
回答by RobinFrcd
It's used to invert boolean Series, see pandas-doc.
它用于反转布尔系列，请参阅pandas-doc。
