Eureka moments in Python

[mensanator at aol.com]

On Mar 13, 2:16 am, Steven D'Aprano <s... at REMOVEME.cybersource.com.au>
wrote:
> I'd be interested in hearing people's stories of Eureka moments in Python,
> moments where you suddenly realise that some task which seemed like it
> would be hard work was easy with Python.
>

##    I have this problem where, given a list of non-zero
##    positive integers (sv), I need to calculate threee constants
##    x, y, z where
##
##    x is 2 raised to the power of the sum of the elements in sv,
##
##    y is 3 raised to the power of the count of the elements in sv,
##
##    and
##
##    z is 3**a*2**A + 3**b*2**B + ... + 3**m*2**M + 3**n*2**N
##
##    where a,b,...m,n are 0,1,...len(sv)-2,len(sv)-1 and
##    N is the sum of all elements of sv except the last one,
##    M is the sum of all elements of sv except the last two,
##    ...
##    B is the sum of all elements of sv except the last len(sv)-1,
##    A is the sum of all elements of sv except the last len(sv).
##
##    This turned out to be one of those things that's
##    easier to code than to describe.
##
##    And if you saw my original Excel spreadsheet where I
##    developed it, you'd say Eureka too.

def calc_xyz(sv):
    x = 2**sum(sv)
    y = 3**len(sv)
    z = 0
    for i in xrange(len(sv)):
        z += 3**i * 2**sum(sv[:-(i+1)])
    return (x,y,z)

sv = [1,2,3,4]
print calc_xyz(sv)

##    (1024, 81, 133)