Vincent Davis wrote:
> On Thu, Jan 23, 2014 at 12:02 PM, Peter Otten <__pete...@web.de> wrote:
>>
>> I just noted that the first Python loop can be eliminated:
Oops, I forgot to paste
import string
def chars(a, b):
return "".join(map(chr, range(a, b)))
_mapping = string.maketrans(chars(0, 10), chars(48, 58))
>> def debruijn(k, n):
>> a = k * n * bytearray([0])
>> sequence = bytearray()
>> extend = sequence.extend # factor out method lookup
>> def db(t, p):
>> if t > n:
>> if n % p == 0:
>> extend(a[1: p+1])
>> else:
>> a[t] = a[t - p]
>> db(t + 1, p)
>> for j in xrange(a[t - p] + 1, k):
>> a[t] = j
>> db(t + 1, t)
>> db(1, 1)
>> return sequence.translate(_mapping)
>
>
> I am not really sure what _mapping should be. The code above does not run
> because
> NameError: global name '_mapping' is not defined
> I tried to get the bytearray
>
> sequence to convert to ascii but don't know how to.
It does the same as adding 48 to every byte in the first variant:
>>> import string
>>> def chars(a, b):
... return "".join(map(chr, range(a, b)))
...
>>> _mapping = string.maketrans(chars(0, 10), chars(48, 58))
>>> b = bytearray(range(10))
>>> b
bytearray(b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t')
>>> b.translate(_mapping)
bytearray(b'0123456789')
The disadvantage of this approach is that it produces a new bytearray, i. e.
it increases the peak amount of memory used by the function significantly.
--
https://mail.python.org/mailman/listinfo/python-list
