R-如何编写一个循环，将一个包中已经内置的函数应用到一个df的所有列中，并填充另一个df？

import pandas as pd

df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6], 'C': [7, 8, 9]})
new_df = pd.DataFrame()

def my_function(x):
    return x * 2

for column in df.columns:
    new_df[column] = df[column].apply(my_function)

print(new_df)

import pandas as pd

df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6], 'C': [7, 8, 9]})
new_df = pd.DataFrame()

def my_function(x):
    return x * 2

for column in df.columns:
    new_df[column] = df[column].apply(my_function)

print(new_df)