title: How to extract the top half of the most frequent values in a list (not a dictionnary)
body: <p>I have a list of values and want to extract the top half of the most frequent ones.
  My list is in mat_sup
  I used :
  <code>mat_sup = np.column_stack(np.unique(mat_sup, return_counts=True))</code>
  which gives me the values and their number of appearances, cool.
  The I used :
  <code>mat_sup = mat_sup[np.core.records.fromarrays([mat_sup[:,1]],names='a').argsort()]</code>
  to sort my list based on the numbers in the second column (number of appearances).
  Unfortunately, numbers are stored as texts and the sort does not give the expected result.
  Any solution please?</p>