Pandas DataFrame 排除列

Python 1年前 100

本教程解释了我们如何从一个 DataFrame 中选择除一列以外的所有列。我们将在本文中使用下面的 DataFrame 示例。

import pandas as pd
stocks_df = pd.DataFrame({
    'Stock': ["Amazon","Tesla","Facebook","Boeing"],
    'Price(in $)':  [3180,835,267,209],
    'Sector':["Technology","Technology","Technology","Aircraft"]
})
print("Stocks Dataframe:")
print(stocks_df,"\n")

输出：

Stocks Dataframe:
      Stock  Price(in $)      Sector
0    Amazon         3180  Technology
1     Tesla          835  Technology
2  Facebook          267  Technology
3    Boeing          209    Aircraft

Pandas 使用 `loc` 属性选择除一列以外的所有列

import pandas as pd
stocks_df = pd.DataFrame({
    'Stock': ["Amazon","Tesla","Facebook","Boeing"],
    'Price(in $)':  [3180,835,267,209],
    'Sector':["Technology","Technology","Technology","Aircraft"]
})
print("Stocks Dataframe:")
print(stocks_df,"\n")
print("Stocks DataFrame excluding Sector Column:")
filtered_df=stocks_df.loc[:,stocks_df.columns!="Sector"]
print(filtered_df,"\n")

输出：

Stocks Dataframe:
      Stock  Price(in $)      Sector
0    Amazon         3180  Technology
1     Tesla          835  Technology
2  Facebook          267  Technology
3    Boeing          209    Aircraft
Stocks DataFrame excluding Sector Column:
      Stock  Price(in $)
0    Amazon         3180
1     Tesla          835
2  Facebook          267
3    Boeing          209

它从 DataFrame stocks_df 中选择除 Sector 列以外的所有元素，将结果分配给 filtered_df，然后显示 filetered_df 的内容。

loc 属性根据指定的行和列选择元素。loc 属性中:符号在 , 前指定我们需要选择所有的行。对于列，我们指定只选择名称不是 Sector 的列。因此，它将选择除 Sector 列以外的所有列。

Pandas 使用 `drop()` 方法选择除一列以外的所有列

我们可以使用 drop() 方法，通过在方法中设置 axis=1，从 DataFrame 中删除指定的列。

import pandas as pd
stocks_df = pd.DataFrame({
    'Stock': ["Amazon","Tesla","Facebook","Boeing"],
    'Price(in $)':  [3180,835,267,209],
    'Sector':["Technology","Technology","Technology","Aircraft"]
})
print("Stocks Dataframe:")
print(stocks_df,"\n")
print("Stocks DataFrame excluding Sector Column:")
filtered_df=stocks_df.drop("Sector",axis=1)
print(filtered_df,"\n")

输出：

Stocks Dataframe:
      Stock  Price(in $)      Sector
0    Amazon         3180  Technology
1     Tesla          835  Technology
2  Facebook          267  Technology
3    Boeing          209    Aircraft
Stocks DataFrame excluding Sector Column:
      Stock  Price(in $)
0    Amazon         3180
1     Tesla          835
2  Facebook          267
3    Boeing          209

它从 stocks_df DataFrame 中删除 Sector 列，并将结果分配给 filtered_df。

我们也可以通过使用 drop() 方法从 DataFrame 中删除多个列。我们提供一个列名列表作为 drop() 方法的参数。

import pandas as pd
stocks_df = pd.DataFrame({
    'Stock': ["Amazon","Tesla","Facebook","Boeing"],
    'Price(in $)':  [3180,835,267,209],
    'Sector':["Technology","Technology","Technology","Aircraft"]
})
print("Stocks Dataframe:")
print(stocks_df,"\n")
print("Stocks DataFrame excluding Sector and Price Column:")
filtered_df=stocks_df.drop(["Sector","Price(in $)"],axis=1)
print(filtered_df,"\n")

输出：

Stocks Dataframe:
      Stock  Price(in $)      Sector
0    Amazon         3180  Technology
1     Tesla          835  Technology
2  Facebook          267  Technology
3    Boeing          209    Aircraft
Stocks DataFrame excluding Sector and Price Column:
      Stock
0    Amazon
1     Tesla
2  Facebook
3    Boeing

它从 stocks_df DataFrame 中排除了 Price(in $) 和 Sector 列。

Pandas 使用 `difference()` 方法选择除一列外的所有列

import pandas as pd
stocks_df = pd.DataFrame({
    'Stock': ["Amazon","Tesla","Facebook","Boeing"],
    'Price(in $)':  [3180,835,267,209],
    'Sector':["Technology","Technology","Technology","Aircraft"]
})
print("Stocks Dataframe:")
print(stocks_df,"\n")
print("Stocks DataFrame excluding Sector Column:")
filtered_df=stocks_df[stocks_df.columns.difference(['Sector'])]
print(filtered_df,"\n")

输出：

Stocks Dataframe:
      Stock  Price(in $)      Sector
0    Amazon         3180  Technology
1     Tesla          835  Technology
2  Facebook          267  Technology
3    Boeing          209    Aircraft
Stocks DataFrame excluding Sector Column:
   Price(in $)     Stock
0         3180    Amazon
1          835     Tesla
2          267  Facebook
3          209    Boeing