我有一个dataframe写个排序函数sort fun，

可以按照指定的列进行排序，也可以选择升序或降序排序。

以下是一个示例代码：

import pandas as pd

def sort_fun(df, column, ascending=True):
    """Sorts a dataframe by a specified column.

    Args:
        df (pandas.DataFrame): The dataframe to be sorted.
        column (str): The name of the column to sort by.
        ascending (bool, optional): Whether to sort in ascending order (default True).

    Returns:
        pandas.DataFrame: The sorted dataframe.
    """
    sorted_df = df.sort_values(by=column, ascending=ascending)
    return sorted_df

使用示例：

# create a sample dataframe
data = {'Name': ['Alice', 'Bob', 'Charlie', 'David', 'Eva'],
        'Age': [23, 42, 31, 28, 35],
        'Salary': [50000, 60000, 55000, 65000, 70000]}
df = pd.DataFrame(data)

# sort by Age in ascending order
sorted_df = sort_fun(df, 'Age')
print(sorted_df)

# sort by Salary in descending order
sorted_df = sort_fun(df, 'Salary', ascending=False)
print(sorted_df)

输出结果：

      Name  Age  Salary
0    Alice   23   50000
3    David   28   65000
2  Charlie   31   55000
4      Eva   35   70000
1      Bob   42   60000

      Name  Age  Salary
4      Eva   35   70000
3    David   28   65000
1      Bob   42   60000
2  Charlie   31   55000
0    Alice   23   50000