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

[Robert]

On Tuesday, January 5, 2016 at 3:37:53 PM UTC-5, John Gordon wrote:
> In <e9f1d94f-4dd6-49b5-bf5c-bbcdc8d304e8 at googlegroups.com> Robert <r-- at gmail.com> writes:
> 
> > ////////////
> > # represent the experiments
> > head_counts = np.array([5,9,8,4,7])
> 
> The code doesn't define 'np', so this line should produce an error.
> 
> The code you linked contains this import:
> 
>     import numpy as np
> 
> However you didn't show it here, so I wonder if you posted the real code.
> 
> > 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. 
> > //////////////
> 
> The built-in function sum() returns a single value, not a list, so this
> is a reasonable error.
> 
> I suspect the code actually intended to call numpy.sum(), which does
> return a list (or something like a list).
> 
> -- 
> John Gordon                   A is for Amy, who fell down the stairs
> gordon at panix.com              B is for Basil, assaulted by bears
>                                 -- Edward Gorey, "The Gashlycrumb Tinies"

Thanks, John. When I typed my new thought, your reply came. You are right.
 The attached message missed numpy import (In my file, it had).

Now, I cannot use np.sum. It has an error, see below please. How can I use
the numpy sum()?

Thanks,
/////////
import numpy as np

In [154]: np.sum(expectation_A)[0]
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-154-1e2cbda689a3> in <module>()
----> 1 np.sum(expectation_A)[0]

IndexError: invalid index to scalar variable.