Traceback (most recent call last): File "E:\pythonProject\ADMM\testa.py", line 30, in <module> X = data[:, :-1]

This error occurs when trying to access a column in a pandas DataFrame using an invalid key. In this case, the key used is a tuple containing two slices, which is not a valid way to access columns. To fix this error, check the key used to access the DataFrame and make sure it is a valid column name or index. If using a slice, make sure it is a valid slice that includes all necessary columns.