如何将所有日期列相减(以排列方式)并将它们存储在新的pandas DataFrame中？

import pandas as pd
import numpy as np

data = {'Date1': ['2022-01-01', '2022-01-02', '2022-01-03'],
        'Date2': ['2022-01-04', '2022-01-05', '2022-01-06'],
        'Date3': ['2022-01-07', '2022-01-08', '2022-01-09']}
df = pd.DataFrame(data)

df['Date1'] = pd.to_datetime(df['Date1'])
df['Date2'] = pd.to_datetime(df['Date2'])
df['Date3'] = pd.to_datetime(df['Date3'])

diff_df = pd.DataFrame()

for i in range(1, len(df.columns)+1):
    for j in range(i+1, len(df.columns)+1):
        diff_col_name = df.columns[i-1] + '-' + df.columns[j-1]
        diff_df[diff_col_name] = (df.iloc[:, i-1] - df.iloc[:, j-1]).dt.days

print(diff_df)