Home Original page

dynamic names

Robert Brewer fumanchu at amor.org
Sun Mar 7 17:08:39 EST 2004 
Val Bykoski wrote:
> I'm currently in a familiar to many business of filing my tax
> return.  Being a big fan of Python and to make the process 
> less painful, 
> i started by writing my favored schedules A,B,C, and the most favored 
> form 1040 in Python.  Everything was a real fun until i got to the
> very famous motif "add lined Lx to Ly".
> This is my naive (master)piece:
> 
> def sumL(L1,L2):
>    # sum up a range of Ls
>    tot=0.
>    for L in range(L1,L2+1): 
>       #nL=exec("L%s" % L)
>       tot=tot + ("L%s" % L)
>    return tot

Val,

If I were writing the same thing, I would probably stop using a separate
name for L1, L2, etcetera; instead I would put them in a list:

def sum_lines(lines, lowerbound, upperbound):
    tot=0.
    for line in lines[lowerbound:upperbound + 1]: 
        tot += line
    return tot

>>> lines = [3.0, 4.0, 5.0, 6.0, 7.0]
>>> sum_lines(lines, 2, 4)
18.0

Of course, once you've put them in a list, you can just use the builtin
sum() function:

>>> sum(lines[2:5])
18.0

...which saves the extra function definition and call overhead, and
makes your code more readable and more manageable. Hope that helps!


Robert Brewer
MIS
Amor Ministries
fumanchu at amor.org
More information about the Python-list mailing list