import math
import numpy as np
from operator import itemgetter
from itertools import groupby

def removeIncomplete(id):

    idx=[(i,j) for (i,j) in enumerate(id)]
    str_lst=[str(i) for i in id]
    a=[list(g) for k,g in groupby(sorted(str_lst),key=itemgetter(0))]
    b=[float(x) for _list in a if len(_list)==3 for x in _list ]
    idComplete = [j for i,j in idx if j in b]

    idComplete = np.around(idComplete, decimals=1)
    return idComplete

print(removeIncomplete(np.array([1.3, 2.2, 2.3, 4.2, 5.1, 3.2, 5.3, 3.3, 2.1, 1.1, 5.2, 3.1])))