if t[i] == b'CE' and t[j] == 'CE':

 elif t[i]=="b'O'" and t[j]=="b'CE'":

if t[i] == b'\xce' and t[j] == 'CE':

t = np.loadtxt("ceo2_sphere_20.xyz", usecols=[0], unpack = True, skiprows = 2, dtype = "str")
x, y, z = np.loadtxt("ceo2_sphere_20.xyz", usecols=[1,2,3], unpack = True, skiprows = 2)
for i in range(1 , len(x)):
    for j in range (0, i):
        print(i)
        rbuf = find_r (x[i]-x[j], y[i] - y[j], z[i] - z[j])
        index = int (np.around(rbuf/dr))
        if t[i] == b'CE' and t[j] == 'CE':
            hist1[index] += 2*ff1*ff1/ff_av/ff_av
        elif t[i]=="b'O'" and t[j]=="b'CE'":
            hist2[index] += 2*ff1*ff2/ff_av/ff_av
        elif t[i]=="b'O'" and t[j]=="b'O'":
            hist3[index] += (2*ff2*ff2)/ff_av/ff_av

        print(i, j, t[i], t[j], type(t[i]), type(t[j]))
        if t[i] == b'CE' and t[j] == 'CE':

>>> A = 0
>>> B = 0
>>> for i in range(1 , len(x)):
...     for j in range (0, i):
...         if t[i] == 'CE' and t[j] == 'CE':
...             A += 1
...         elif t[i] == 'O' and t[j] == 'O':
...             B += 1
>>> A
3741
>>> B
21528