python原子数据类型(python atomic data types)
这里写的是Python有原子和引用对象类型。 原子对象是：int，long，complex。 分配原子对象时，会复制它的值，在分配引用对象时会复制它的引用。
我的问题是：为什么然后，当我做代码时，我得到'真'？
a = 1234 b = a print id(a) == id(b)在我看来，我不复制价值，我只是复制参考，无论它是什么类型。
It was written here that Python has both atomic and reference object types. Atomic objects are: int, long, complex. When assigning atomic object, it's value is copied, when assigning reference object it's reference is copied.
My question is: why then, when i do the code bellow i get 'True'?
a = 1234 b = a print id(a) == id(b)It seems to me that i don't copy value, i just copy reference, no matter what type it is.
原文：https://stackoverflow.com/questions/39125486
更新时间：2023-06-05 09:06
最满意答案
如果'列'在索引中。
In [217]: df.loc[(df.index.get_level_values('Site In') == 'Mid') | (df.index.get_level_values('Site Out') == 'Mid')] Out[217]: v Site In Site Out Transmission Commodity Mid North hvac Elec 1 South hvac Elec 1 North Mid hvac Elec 1 South Mid hvac Elec 1
如果它是一个扁平的数据帧，请使用
In [168]: df.loc[(df['Site In'] == 'Mid') | (df['Site Out'] == 'Mid')] Out[168]: Site In Site Out Transmission Commodity 0 Mid North hvac Elec 1 Mid South hvac Elec 2 North Mid hvac Elec 4 South Mid hvac Elec要么
In [169]: df.loc[df['Site In'].eq('Mid') | df['Site Out'].eq('Mid')] Out[169]: Site In Site Out Transmission Commodity 0 Mid North hvac Elec 1 Mid South hvac Elec 2 North Mid hvac Elec 4 South Mid hvac ElecIf 'columns' are in index.
In [217]: df.loc[(df.index.get_level_values('Site In') == 'Mid') | (df.index.get_level_values('Site Out') == 'Mid')] Out[217]: v Site In Site Out Transmission Commodity Mid North hvac Elec 1 South hvac Elec 1 North Mid hvac Elec 1 South Mid hvac Elec 1
If it's a flat dataframe, use
In [168]: df.loc[(df['Site In'] == 'Mid') | (df['Site Out'] == 'Mid')] Out[168]: Site In Site Out Transmission Commodity 0 Mid North hvac Elec 1 Mid South hvac Elec 2 North Mid hvac Elec 4 South Mid hvac ElecOr
In [169]: df.loc[df['Site In'].eq('Mid') | df['Site Out'].eq('Mid')] Out[169]: Site In Site Out Transmission Commodity 0 Mid North hvac Elec 1 Mid South hvac Elec 2 North Mid hvac Elec 4 South Mid hvac Elec
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