赋值警告：A value is trying to be set on a copy of a slice from a DataFrame.
错误代码：
示例一：df['supplierId'] = 'FRESH GO LIMITED'
示例二：df.rename(columns={'one':'one_a'}, inplace=True)``df.drop(['one', 'two', 'three'], axis=1, inplace=True)
错误：
:::warning
SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
df[‘supplierId’] = ‘FRESH GO LIMITED’ # 供应商
SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame
See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
df.rename(columns={
:::
解决方案（示例一）：
注：先检查示例二有没有warning，如果有，则可能导致示例一的错误，解决掉示例二的warning就可以了
- 方法一：使用单一赋值操作（loc）：
data.loc[:, 'supplierId'] = 'FRESH GO LIMITED' - 方法二：创建副本再赋值：
winners = data.loc[data.bid == data.price].copy()winners.loc[304, 'bidder'] = 'therealname'
- 方法三：关闭警告（强烈不推荐）：
pd.set_option('mode.chained_assignment', None)
解决方案（示例二）：
- 方法一：
df2 = df.rename(columns={'one':'one_a'})
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