scoreatprecentile return wrong values when used on array with NaNs (Trac #1653) #2178
Description
Original ticket http://projects.scipy.org/scipy/ticket/1653 on 2012-05-02 by trac user imrisofer, assigned to unknown.
the output of scoreatprecentile changed according to the number of Not-a-Numbers in the array
#create arrays
#all of the arrays have the same precentiles
a1 = array([1,2,3,4])
a2 = array([1,2,3,4,nan])
a3 = array([1,2,3,4,nan,nan])
#put all arrays in one list
l = [a1, a2, a3]
#check precentiles of each array
for i in range(3):
print "array with %d NaNs" %(i)
print "q25: ", scoreatpercentile(l[i], 25)
print "q50: ", scoreatpercentile(l[i], 50)
print "q75: ", scoreatpercentile(l[i], 75)
print
output:
array with 0 NaNs
q25: 1.75
q50: 2.5
q75: 3.25
array with 1 NaNs
q25: 2.0
q50: 3.0
q75: 4.0
array with 2 NaNs
q25: 2.25
q50: 3.5
q75: nan