更改Pandas数据结构中元素的值 [英] Changing Values of elements in Pandas Datastructure

问题描述

我已经导入了.xls文件
和

I have imported .xls file with

ene2 = pd.read_excel('Energy Indicators.xls', index=False)

头看起来像这样

print(ene2.head())          
          Country Energy Supply Energy Supply per Capita % Renewable's
15             NaN    Petajoules               Gigajoules             %
16     Afghanistan           321                       10       78.6693
17         Albania           102                       35           100
18         Algeria          1959                       51       0.55101
19  American Samoa           ...                      ...      0.641026

让我说我使用FOR循环交换了一些值

lets say that i used FOR loop to exchange some values

for value in ene2['Energy Supply']:
    if value == 'Petajoules':
        value = 'Gigajoules'
        print(value)

在循环内s看起来不错

但是再次打印头，

print(ene2.head())  

告诉我，尚未对DataStructure iteslf进行任何更改

show me that, no change has been applied to the DataStructure iteslf

和尾巴看起来与上面完全一样，但是我希望它会有所变化。

and tail looks exactly as above, but i expected it go got change.

推荐答案

而不是：

value = 'Gigajoules'

执行以下操作：

ene2.loc[ene2['Energy Supply'] == value, 'Energy Supply'] = 'Gigajoules'

通过使用 .loc 筛选正确的行和列，将其设置为相关的单元格。另一个答案是更简单的方法，但是我想让您了解，您并没有将更改仅通过value = blah回到数据框。

You have to set it to the relevant cell, by filtering for the correct rows and columns with .loc. The other answer is the simpler method, but I wanted you to understand that you are not making the changes back to the dataframe with just value = blah.

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