Generating all ordered substrings of a string

[Gerard Flanagan]

girish at it.usyd.edu.au wrote:
> Hi,
>  I want to generate all non-empty substrings of a string of length >=2.
> Also,
> each substring is to be paired with 'string - substring' part and vice
> versa.
>  Thus, ['abc'] gives me [['a', 'bc'], ['bc', 'a'], ['ab', 'c'], ['c',
> 'ab'], ['b', 'ac'], ['ac', 'b']] etc.
>  Similarly, 'abcd' should give me [['a', 'bcd'], ['bcd', 'a'], ['abc',
> 'd'], ['d', 'abc'], ['b', 'acd'], ['acd', 'b'],['c', 'abd'], ['abd', 'c'],
> ['ab', 'cd'], ['cd', 'ab'], ['bc', 'ad'], ['ad', 'bc'], ['ac',
> 'bd'],['bd','ac']]
>

from a previous post
(http://groups.google.com/group/comp.lang.python/browse_frm/thread/fa40c76544b1c515/cef5b578bb00e61b?lnk=st&q=&rnum=23#cef5b578bb00e61b)

def nkRange(n,k):
    m = n - k + 1
    indexer = range(0, k)
    vector = range(1, k+1)
    last = range(m, n+1)
    yield vector
    while vector != last:
        high_value = -1
        high_index = -1
        for i in indexer:
            val = vector[i]
            if val > high_value and val < m + i:
                high_value = val
                high_index = i
        for j in range(k - high_index):
            vector[j+high_index] = high_value + j + 1
        yield vector

def kSubsets(s, k):
    for vector in nkRange(len(s),k):
        yield ''.join( s[i-1] for i in vector )

print list( kSubsets('abcd',2) )

['ab', 'ac', 'ad', 'bc', 'bd', 'cd']