Blog "about python 3"

[Roy Smith]

In article <mailman.4929.1388896998.18130.python-list at python.org>,
 Rustom Mody <rustompmody at gmail.com> wrote:

> On Sun, Jan 5, 2014 at 8:50 AM, Roy Smith <roy at panix.com> wrote:
> > I wrote:
> >> > I realize I'm taking this statement out of context, but yes, sometimes
> >> > fast is more important than correct.
> >
> > In article <52c8c301$0$29998$c3e8da3$5496439d at news.astraweb.com>,
> >  Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
> >> Fast is never more important than correct.
> >
> > Sure it is.
> >
> > Let's imagine you're building a system which sorts packages for
> > delivery.  You sort 1 million packages every night and put them on
> > trucks going out for final delivery.
> >
> > Some assumptions:
> >
> > Every second I can cut from the sort time saves me $0.01.
> >
> > If I mis-sort a package, it goes out on the wrong truck, doesn't get
> > discovered until the end of the day, and ends up costing me $5
> > (including not just the direct cost of redelivering it, but also
> > factoring in ill will and having to make the occasional refund for not
> > meeting the promised delivery time).
> >
> > I've got a new sorting algorithm which is guaranteed to cut 10 seconds
> > off the sorting time (i.e. $0.10 per package).  The problem is, it makes
> > a mistake 1% of the time.
> >
> > Let's see:
> >
> > 1 million packages x $0.10 = $100,000 saved per day because I sort them
> > faster.  10,000 of them will go to the wrong place, and that will cost
> > me $50,000 per day.  By going fast and making mistakes once in a while,
> > I increase my profit by $50,000 per day.
> >
> > The numbers above are fabricated, but I'm sure UPS, FexEx, and all the
> > other package delivery companies are doing these sorts of analyses every
> > day.  I watch the UPS guy come to my house.  He gets out of his truck,
> > walks to my front door, rings the bell, waits approximately 5
> > microseconds, leaves the package on the porch, and goes back to his
> > truck.  I'm sure UPS has figured out that the amortized cost of the
> > occasional stolen or lost package is less than the cost for the delivery
> > guy to wait for me to come to the front door and sign for the delivery.
> >
> > Looking at another problem domain, let's say you're a contestant on
> > Jeopardy.  If you listen to the entire clue and spend 3 seconds making
> > sure you know the correct answer before hitting the buzzer, it doesn't
> > matter if you're right or wrong.  Somebody else beat you to the buzzer,
> > 2.5 seconds ago.
> >
> > Or, let's take an example from sports.  I'm standing at home plate
> > holding a bat.  60 feet away from me, the pitcher is about to throw a
> > baseball towards me at darn close to 100 MPH (insert words like "bowl"
> > and "wicket" as geographically appropriate).  400 ms later, the ball is
> > going to be in the catcher's glove if you don't hit it.  If you have an
> > absolutely perfect algorithm to determining if it's a ball or a strike,
> > which takes 500 ms to run, you're going back to the minor leagues.  If
> > you have a 300 ms algorithm which is right 75% of the time, you're
> > heading to the hall of fame.
> 
> 
> Neat examples -- thanks
> Only minor quibble isnt $5 cost of mis-sorting a gross underestimate?

I have no idea.  Like I said, the numbers are all fabricated.

I do have a friend who used to work for UPS.  He told me lots of UPS 
efficiency stories.  One of them had to do with mis-routed packages.  
IIRC, the process for dealing with a mis-routed package was to NOT waste 
any time trying to figure out why it was mis-routed.  It was just thrown 
back into the input hopper to go through the whole system again.  The 
sorting software kept track of how many times it had sorted a particular 
package.  Only after N attempts (where N was something like 3), was it 
kicked out of the automated process for human intervention.