def df_filter_col_sum(df, threshold, take_abs=True):
  ''' filter columns in matrix at some threshold
  and remove rows that have all zero values '''

  from copy import deepcopy
  from .__init__ import Network
  net = Network()

  if take_abs is True:
    df_copy = deepcopy(df['mat'].abs())
  else:
    df_copy = deepcopy(df['mat'])

  df_copy = df_copy.transpose()
  df_copy = df_copy[df_copy.sum(axis=1) > threshold]
  df_copy = df_copy.transpose()
  df_copy = df_copy[df_copy.sum(axis=1) > 0]

  if take_abs is True:
    inst_rows = df_copy.index.tolist()
    inst_cols = df_copy.columns.tolist()
    df['mat'] = grab_df_subset(df['mat'], inst_rows, inst_cols)

    if 'mat_up' in df:
      df['mat_up'] = grab_df_subset(df['mat_up'], inst_rows, inst_cols)
      df['mat_dn'] = grab_df_subset(df['mat_dn'], inst_rows, inst_cols)

    if 'mat_orig' in df:
      df['mat_orig'] = grab_df_subset(df['mat_orig'], inst_rows, inst_cols)

  else:
    df['mat'] = df_copy

  return df
filter columns in matrix at some threshold
  and remove rows that have all zero values