[Tutor] get the mode of a list

[Terry Carroll]

On Thu, 21 Oct 2004, Nick Lunt wrote:

> I want to return the mode of a list, just to clarify the mode is the most
> frequently occurring member of a list in my case.

Here's my take.  I'll bet it has some limitations I'm not aware of.  It 
returns a list with two elements.  The first is the number of times the 
mode value occurs, and the second is a list of modes.

For the example below, mode([1, 2, 4, 2, 4, 5, 2, 4, 100]), where 2 and 3 
are the modes, each occuring 3 times, it returns [3, [2, 4]]

def mode(mylist):
   _hist_dict={}
   for item in mylist:
      _hist_dict[item]=_hist_dict.get(item,0)+1
   _modevalue=max(_hist_dict.values())
   _returned_list=[]
   for key in _hist_dict.keys():
      if _hist_dict[key] == _modevalue:
          _returned_list.append(key)
   return [_modevalue, _returned_list]


if __name__ == "__main__":
  testlist = [1, 2, 4, 2, 4, 5, 2, 4, 100]
  modelist = mode(testlist)
  print modelist