i'm lost in list manipulation

[GrelEns]

hello,

having a list like ['a', 'b', 'c', 'd'] i would like to get

[['a', '-', 'b', 'c', 'd'],
['a', 'b', '-', 'c', 'd'],
['a', 'b', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c', 'd'],
['a', 'b', '-', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c','-', 'd']]

that is adding successively an item between at all the available place, and
i just can't get my brain doing that :(

thank a lot if you could help...

[Scott David Daniels]

GrelEns wrote:

hello,

having a list like ['a', 'b', 'c', 'd'] i would like to get

[['a', '-', 'b', 'c', 'd'],
['a', 'b', '-', 'c', 'd'],
['a', 'b', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c', 'd'],
['a', 'b', '-', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c','-', 'd']]

that is adding successively an item between at all the available place, and
i just can't get my brain doing that :(

Maybe:
Think of all possible places. How many are there? At each of these
places you either put a dash or not. Sounds like binary to me.

--
-Scott David Daniels
Sc***********@A cm.Org

[wes weston]

GrelEns wrote:

hello,

having a list like ['a', 'b', 'c', 'd'] i would like to get

[['a', '-', 'b', 'c', 'd'],
['a', 'b', '-', 'c', 'd'],
['a', 'b', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c', 'd'],
['a', 'b', '-', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c','-', 'd']]

that is adding successively an item between at all the available place, and
i just can't get my brain doing that :(

thank a lot if you could help...

GrelEns,
Scott has it. For a start string of 4 chars there are 3 gaps/spaces
for the dash/not dash. So, there are 8 possible results. One of these
has no dashes - you may want to throw this one out. The "gap" strings
needs to be:
"000"
"001"
"010"
"011"
"100"
"101"
"110"
"111"
where the 1's are your character; "-"
Throw out the first one and insert into the gaps in the original string.
wes

[Paul Watson]

"GrelEns" <gr*****@NOSPAM yahoo.NOTNEEDED fr> wrote in message
news:40******** *************** @news.free.fr.. .

hello,

having a list like ['a', 'b', 'c', 'd'] i would like to get

[['a', '-', 'b', 'c', 'd'],
['a', 'b', '-', 'c', 'd'],
['a', 'b', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c', 'd'],
['a', 'b', '-', 'c', '-', 'd'],
['a', '-', 'b', '-', 'c','-', 'd']]

that is adding successively an item between at all the available place, and i just can't get my brain doing that :(

thank a lot if you could help...

Does this look like it would work?

alist = ['a', 'b', 'c', 'd']
nlist = range(len(alist ) - 1)
finallist = []

for x in range(2 ** (len(alist) - 1)):
if x == 0: continue #remove this if you want one with no dashes
rlist = [alist[0]]
for y in nlist:
if x & (1 << y): rlist.append('-')
rlist.append(al ist[y + 1])
finallist.appen d(rlist)
del rlist

print finallist
$ ./listins.py
[['a', '-', 'b', 'c', 'd'], ['a', 'b', '-', 'c', 'd'], ['a', '-', 'b', '-',
'c', 'd'], ['a', 'b', 'c', '-', 'd'], ['a',
'-', 'b', 'c', '-', 'd'], ['a', 'b', '-', 'c', '-', 'd'], ['a', '-', 'b',
'-', 'c', '-', 'd']]