Disclaimer - I recognize this is not a practical exercise. There are
many implementations around that would do the job better, more
efficiently (Meaning in C) or whatever.
I caught some thread about sorting and started thinking about shell
sort.... and as part of my trying to pythonise my mind and break my
java mindset
So I decided to tackle this old school problem with the python mindset.
I played around with some list comprehensions, trying to use slicing
inteligently etc. Anyway this is what I came up with. If anyone has
suggestions on a more pythonic way to go (all attempts at using list
comprehensions turned into unruly rubbish quite quickly) I'd
appreciate the input. An aside - can anyone tell me where the use +=
and -= is documented? it works but I can't find it in my docs.
(don't ask about shellSorters 1 thru 3)
class shellSorter4(object):
def __init__(self,gapSeq):
self.gapSeq = gapSeq # gap sequences are
notoriously hard to tune
self.gapSeq.sort(reverse=True)
def sort(self,myList):
for gap in self.gapSeq:
for i in range(1,gap+1):
self.gapInsertionSort(myList,i,gap)
def gapInsertionSort(self,theList,start,gap):
for i in range(start,len(theList),gap):
j = i
curElem = theList[j]
while (j > 0) and (theList[j-gap] > curElem):
j -=gap # undocumented
feature??
if j!=i:
theList.insert(j,theList.pop(i))
theList.insert(j+gap,theList.pop(j+1))
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