def split_df(df, columns_split):
  """Split a dataframe into two by column.

  Args:
    df (pandas dataframe): input dataframe to split.
    columns_split (int): Column at which to split the dataframes.

  Returns:
    df1, df2 (pandas dataframes): Split df into two dataframe based on column.
    The first has the first column_split-1 columns, and the second has columns
    columns_split onward.

  """
  return df.iloc[:, :columns_split], df.iloc[:, columns_split:]