append values to a single list or array from a loop in python

Question

import numpy as np
import itertools
a = np.array([[1, 1, 3, 0, 0, 3, 2], [1, 3, 0, 0, 0, 3, 2], [1, 1, 10, 0, 0, 1, 0]])
for row in a:
    sites = a.shape[0]
    species = a.shape[1]
    Chao = []
    sing = np.where(row == 1, 1, 0)
    doub = np.where(row == 2, 1, 0)
    spec = np.where(row > 0, 1, 0)
    F1 = (sum(sing))**2
    F2 = float((sum(doub)))*2
    Sobs = sum(spec)
    if F2 == 0:
        Ch = Sobs
    else:
        Ch = Sobs + (F1/F2)
    Chao.append(Ch)
    print Chao

when I print Chao, the product of this loop I currently have this:

[7][4.5][4]

However, I would like either an array or list that looks like this:

([7][4.5][4])

What functions in numpy or list will allow me to do this in python?

Answer 1

The logic are correct. The Chao list should to be initialized outside of the loop.