Why is there difference between cmd line and .py file?

[Robert]

On Tuesday, January 5, 2016 at 3:26:15 PM UTC-5, Robert wrote:
> Hi,
> 
> I run below code, which is downloaded from link:
> 
> http://stackoverflow.com/questions/15513792/expectation-maximization-coin-toss-examples?rq=1
> 
> 
> 
> ////////////
> # represent the experiments
> head_counts = np.array([5,9,8,4,7])
> tail_counts = 10-head_counts
> experiments = zip(head_counts,tail_counts)
> 
> # initialise the pA(heads) and pB(heads)
> pA_heads = np.zeros(100); pA_heads[0] = 0.60
> pB_heads = np.zeros(100); pB_heads[0] = 0.50
> 
> # E-M begins!
> delta = 0.001  
> j = 0 # iteration counter
> improvement = float('inf')
> while (improvement>delta):
>     expectation_A = np.zeros((5,2), dtype=float) 
>     expectation_B = np.zeros((5,2), dtype=float)
>     for i in range(0,len(experiments)):
>         e = experiments[i] # i'th experiment
>         ll_A = get_mn_log_likelihood(e,np.array([pA_heads[j],1-pA_heads[j]])) # loglikelihood of e given coin A
>         ll_B = get_mn_log_likelihood(e,np.array([pB_heads[j],1-pB_heads[j]])) # loglikelihood of e given coin B
> 
>         weightA = math.exp(ll_A) / ( math.exp(ll_A) + math.exp(ll_B) ) # corresponding weight of A proportional to likelihood of A 
>         weightB = math.exp(ll_B) / ( math.exp(ll_A) + math.exp(ll_B) ) # corresponding weight of B proportional to likelihood of B                            
> 
>         expectation_A[i] = np.dot(weightA, e) 
>         expectation_B[i] = np.dot(weightB, e)
> 
>     print "sum(expectation_A)[0]", sum(expectation_A)[0]
>     pA_heads[j+1] = sum(expectation_A)[0] / sum(sum(expectation_A)); 
>     pB_heads[j+1] = sum(expectation_B)[0] / sum(sum(expectation_B));
> //////////
> The print message is: 
> sum(expectation_A)[0] 21.2974818963
> sum(expectation_A)[0] 19.2093824201
> sum(expectation_A)[0] 19.4102767983
> sum(expectation_A)[0] 19.7538328728
> sum(expectation_A)[0] 19.9753285438
> sum(expectation_A)[0] 20.0879016403
> sum(expectation_A)[0] 20.139820175
> sum(expectation_A)[0] 20.1628374165
> 
> 
> 
> When I check below in detail in interactive mode (Canopy Python shell),
>  
> sum(expectation_A)[0]
> 
> it has error:
> /////////////
> sum(expectation_A)[0]
> ---------------------------------------------------------------------------
> IndexError                                Traceback (most recent call last)
> <ipython-input-145-d6f33dff0343> in <module>()
> ----> 1 sum(expectation_A)[0]
> 
> IndexError: invalid index to scalar variable. 
> //////////////
> 
> I can see expectation_A content with:
> 
> In[146]:expectation_A
> Out[146]: 
> array([[ 0.52278641,  0.52278641],
>        [ 8.55858656,  0.95095406],
>        [ 6.75024946,  1.68756237],
>        [ 0.1260128 ,  0.1890192 ],
>        [ 4.20520218,  1.80222951]])
> 
> It looks like 
> sum(expectation_A)[0]
> 
> can run in .py file, while it cannot be run in python shell.
> Is it true?
> 
> Thanks,

I just wonder that the cmd line function sum may be different from the 
.py file used. One is numpy package, the other is a general one. Then,
how can I further make it clear for this guess?
Thanks,