IndexError for using pandas dataframe values

[Daiyue Weng]

Hi, I tried to use DataFrame.values to convert a list of columns in a
dataframe to a numpy ndarray/matrix,

matrix = df.values[:, list_of_cols]

but got an error,

IndexError: only integers, slices (:), ellipsis (...), numpy.newaxis
(None) and integer or boolean arrays are valid indices

so what's the problem with the list of columns I passed in?

many thanks