import pandas as pd
import numpy as np

# create a sample DataFrame
df = pd.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6], 'c': [7, 8, 9]})

# convert the DataFrame to a NumPy array
arr = df.values

# replace both diagonals of the array with zeros
np.fill_diagonal(arr, 0)
np.fill_diagonal(np.fliplr(arr), 0)

# convert the array back to a DataFrame
df = pd.DataFrame(arr, columns=df.columns, index=df.index)
df