how to get the ordinal number in list

[Rustom Mody]

On Sunday, August 10, 2014 11:44:23 PM UTC+5:30, Roy Smith wrote:
>  Rustom Mody wrote:

> > >>> l= [6,2,9,12,1,4]
> > >>> sorted(l,reverse=True)[:5]
> > [12, 9, 6, 4, 2]
> > No need to know how sorted works nor [:5]
> > Now you (or Steven) can call it abstract.
> > And yet its 
> > 1. Actual running code in the interpreter
> > 2. Its as close as one can get to a literal translation of your
> >    "Find the 5 largest numbers in a list"
> > [...]
> > All the above are clearer than loops+assignments and can be 
> > taught before them

> I disagree.  For a beginner, you want to be able to break things down 
> into individual steps and examine the result at each point.  If you do:

> > >>> l= [6,2,9,12,1,4]
> > >>> l2 = sorted(l,reverse=True)
> > >>> l2[:5]

> you have the advantage that you can stop after creating l2 and print it 
> out.  The student can see that it has indeed been sorted.  With the 
> chained operations, you have to build a mental image of an anonymous, 
> temporary list, and then perform the slicing operation on that.  Sure, 
> it's the way you or I would write it in production code, but for a 
> beginner, breaking it down into smaller pieces makes it easier to 
> understand.


Yeah Whats the disagreement??

You are writing straight-line code.
I am recommending straight-line code -- another way of saying loops are bad.

Or is it because you are using assignment?

I call that 'nominal' assignment.
Technically its called 'single-assignment'
www.cs.princeton.edu/~appel/papers/ssafun.ps

Its when we have variables that are assigned in multiple places that
we start seeing mathematical abominations like
x = x+1