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up vote 2 down vote favorite

How can I define _SOME CODE_ in the next code fragment in order to get the results shown below?

vector = numpy.array([a,b,c,d])
for i in xrange(4):
    print vector[_SOME CODE_ using i]

It sould give me those results:

[a,b,c]
[a,c,d]
[a,b,d]
[b,c,d]

The order is not important.

share|improve this question
    
What's the intended pattern? Add 1 to some vector components? – Sven Marnach Dec 2 '11 at 16:25
    
vector doesn't contain 3, so you cannot get the desired results with indexing alone. – Charles Dec 2 '11 at 16:28
up vote 3 down vote accepted

Answer for the edited question:

>>> vector = numpy.array([0, 1, 2, 3])
>>> for i in xrange(4):
...     print numpy.r_[vector[:i], vector[i+1:]]
... 
[1 2 3]
[0 2 3]
[0 1 3]
[0 1 2]

Answer for the original question: Here's some random code producing the desired output:

>>> import numpy
>>> vector = numpy.array([0,1,2])
>>> for i in xrange(4):
...     print vector + (vector >= i)
... 
[1 2 3]
[0 2 3]
[0 1 3]
[0 1 2]

I've got no idea if this is what you want -- the requirement specification left some room for interpretation.

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up vote 0 down vote

I think you're trying to find all combinations of size 3 of the vector. You can do this with itertools.combinations like this:

>>> import numpy
>>> import itertools
>>> vector = numpy.array([0, 1, 2, 3])
>>> list(itertools.combinations(vector, 3))
[(0, 1, 2), (0, 1, 3), (0, 2, 3), (1, 2, 3)]
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