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Python Pandas DataFrame.astype() 函数将对象的数据类型改变为指定的数据类型。

pandas.DataFrame.astype() 语法

DataFrame.astype(dtype, copy=True, errors="raise")

参数

返回对象

它返回带有数据类型的 DataFrame。

示例代码：DataFrame.astype() 方法改变一列数据类型

import pandas as pd

dataframe=pd.DataFrame({'Attendance': {0: 60, 1: 100, 2: 80,3: 78,4: 95},
                        'Name': {0: 'Olivia', 1: 'John', 2: 'Laura',3: 'Ben',4: 'Kevin'},
                        'Obtained Marks': {0: 90, 1: 75, 2: 82, 3: 64, 4: 45}})

print("The Original Data Types of the Data frame are: \n")
print(dataframe.dtypes)

dataframe1 = dataframe.astype({'Attendance': 'int32'}).dtypes
print("The Modified Data Types of the Data frame are: \n")
print(dataframe1)

输出：

The Original Data Types of the Data frame are: 

Attendance         int64
Name              object
Obtained Marks     int64
dtype: object
The Modified Data Types of the Data frame are: 

Attendance         int32
Name              object
Obtained Marks     int64
dtype: object

该函数返回了转换的数据类型。我们使用 dtypes() 函数来显示 DataFrame 中各列的数据类型。

示例代码：DataFrame.astype() 方法改变 DataFrame 所有列的数据类型

我们将尝试改变给定 DataFrame 的数据类型。

import pandas as pd
dataframe=pd.DataFrame({'Attendance': {0: 60, 1: 100, 2: 80,3: 78,4: 95},
                        'Name': {0: 'Olivia', 1: 'John', 2: 'Laura',3: 'Ben',4: 'Kevin'},
                        'Obtained Marks': {0: 90, 1: 75, 2: 82, 3: 64, 4: 45}})
print("The Original Data Types of the Data frame are: \n")
print(dataframe.dtypes)

dataframe1 = dataframe.astype('object').dtypes
print("The Modified Data Types of the Data frame are: \n")
print(dataframe1)

输出：

The Original Data Types of the Data frame are: 

Attendance         int64
Name              object
Obtained Marks     int64
dtype: object
The Modified Data Types of the Data frame are: 

Attendance        object
Name              object
Obtained Marks    object
dtype: object

函数返回了修改后的 DataFrame，它已经将所有列的数据类型改为 object。

示例代码：DataFrame.astype() 方法改变数据类型时有异常的情况

现在我们将数据类型 object 设置为 int32。函数将忽略异常，因为我们将传递参数 errors= 'ignore'。

import pandas as pd

dataframe=pd.DataFrame({'Attendance': {0: 60, 1: 100, 2: 80,3: 78,4: 95},
                        'Name': {0: 'Olivia', 1: 'John', 2: 'Laura',3: 'Ben',4: 'Kevin'},
                        'Obtained Marks': {0: 90, 1: 75, 2: 82, 3: 64, 4: 45}})

print("The Original Data Types of the Data frame are: \n")
print(dataframe.dtypes)

dataframe1 = dataframe.astype('int32', errors='ignore').dtypes
print("The Modified Data Types of the Data frame are: \n")
print(dataframe1)

输出：

The Original Data Types of the Data frame are: 

Attendance         int64
Name              object
Obtained Marks     int64
dtype: object
The Modified Data Types of the Data frame are: 

Attendance         int32
Name              object
Obtained Marks     int32
dtype: object

请注意，函数没有引发任何异常。它忽略了这个错误，因为我们将 object 转为 int32。它只是没有改变 Name 列的数据类型。