#8889: multidim'l enumeration over variable length tuples
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Reporter: ecurry | Owner: jason
Type: enhancement | Status: new
Priority: minor | Milestone: sage-wishlist
Component: misc | Keywords:
Author: Eva Curry | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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I would like a function that takes
Input: range (a list)
dim (a positive integer)
Output: a list of vectors or tuples of length dim including all
combinations of range, but with replacement
Example: generate the vertices of the centered unit cube [-1/2,1/2]^dim,
where dim is variable
The functions in sage.misc.mrange almost do this, except it seems that
they require having dim specified ahead of time, whereas I want a function
that I can call in another function where dim will vary.
The function Arrangements in sage.combinat.permutation almost does what I
want, but the list that the digits of the tuple are chosen from must be
larger than dim, and Arrangements selects without replacement. I can
solve my example problem using Arrangements as follows:
{{{
prelist=[]
for i in range(2**d):
if i-2**(d-1) >= 0: prelist.append(1)
else: prelist.append(-1)
list = (1/2)*matrix(Arrangements(prelist,d).list())
}}}
but it seems like there should be one specific function for this.
(Combinations and Permutations are also related, but don't quite do what I
want.)
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8889>
Sage <http://www.sagemath.org>
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