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| Started by | Xiang Zhang <zhangxiangsunny@gmail.com> |
|---|---|
| First post | 2015-05-14 20:58 -0700 |
| Last post | 2015-05-16 01:16 +0100 |
| Articles | 4 — 3 participants |
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Python: How to find out values of all feasible x under constraints. Xiang Zhang <zhangxiangsunny@gmail.com> - 2015-05-14 20:58 -0700
Re: Python: How to find out values of all feasible x under constraints. Peter Otten <__peter__@web.de> - 2015-05-15 09:47 +0200
Re: Python: How to find out values of all feasible x under constraints. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-15 13:35 +0100
Re: Python: How to find out values of all feasible x under constraints. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-16 01:16 +0100
| From | Xiang Zhang <zhangxiangsunny@gmail.com> |
|---|---|
| Date | 2015-05-14 20:58 -0700 |
| Subject | Python: How to find out values of all feasible x under constraints. |
| Message-ID | <12da2c70-fd4e-430b-83d2-fad4ac1e3f8f@googlegroups.com> |
Dear all, I am writing a code using Python now. I want to know how to find out values of all feasible x under constraints. x = [x_1, x_2, x_3,..., x_10] constraints: x_i = 0,1,2,3 or 4, where i=1,2,....10 x_1 + x_2 + x_3 +...+x_10 <= 15 How to find out all the feasible solutions x (domain of x) using python, like [0,0,0,0,0,0,0,0,0,0], [1,1,1,1,1,1,1,1,1,1] etc ? What should be the code? Any hint or help would be highly appreciated! Sincerely, Xiang Zhang
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| From | Peter Otten <__peter__@web.de> |
|---|---|
| Date | 2015-05-15 09:47 +0200 |
| Message-ID | <mailman.30.1431676060.17265.python-list@python.org> |
| In reply to | #90646 |
Xiang Zhang wrote: > I want to know how to find out values of all feasible x under constraints. > > x = [x_1, x_2, x_3,..., x_10] > > > constraints: > x_i = 0,1,2,3 or 4, where i=1,2,....10 > x_1 + x_2 + x_3 +...+x_10 <= 15 That are 5**10 == 9765625 candidates. That's still feasible to check using brute force. > How to find out all the feasible solutions x (domain of x) using python, > like [0,0,0,0,0,0,0,0,0,0], [1,1,1,1,1,1,1,1,1,1] etc ? What should be the > code? > > Any hint or help would be highly appreciated! >>> solutions = [x for x in itertools.product(range(5), repeat=10) if sum(x) <= 15] >>> len(solutions) 1556215 The first ten solutions: >>> solutions[:10] [(0, 0, 0, 0, 0, 0, 0, 0, 0, 0), (0, 0, 0, 0, 0, 0, 0, 0, 0, 1), (0, 0, 0, 0, 0, 0, 0, 0, 0, 2), (0, 0, 0, 0, 0, 0, 0, 0, 0, 3), (0, 0, 0, 0, 0, 0, 0, 0, 0, 4), (0, 0, 0, 0, 0, 0, 0, 0, 1, 0), (0, 0, 0, 0, 0, 0, 0, 0, 1, 1), (0, 0, 0, 0, 0, 0, 0, 0, 1, 2), (0, 0, 0, 0, 0, 0, 0, 0, 1, 3), (0, 0, 0, 0, 0, 0, 0, 0, 1, 4)]
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| From | Mark Lawrence <breamoreboy@yahoo.co.uk> |
|---|---|
| Date | 2015-05-15 13:35 +0100 |
| Message-ID | <mailman.35.1431693331.17265.python-list@python.org> |
| In reply to | #90646 |
On 15/05/2015 04:58, Xiang Zhang wrote: > Dear all, > > I am writing a code using Python now. > > I want to know how to find out values of all feasible x under constraints. > > x = [x_1, x_2, x_3,..., x_10] > > > constraints: > x_i = 0,1,2,3 or 4, where i=1,2,....10 > x_1 + x_2 + x_3 +...+x_10 <= 15 > > How to find out all the feasible solutions x (domain of x) using python, like [0,0,0,0,0,0,0,0,0,0], [1,1,1,1,1,1,1,1,1,1] etc ? What should be the code? > > Any hint or help would be highly appreciated! > > Sincerely, > > Xiang Zhang > There are several constraint libraries on pypi if you don't want to roll your own. See for example https://pypi.python.org/pypi/python-constraint/1.2 -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence
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| From | Mark Lawrence <breamoreboy@yahoo.co.uk> |
|---|---|
| Date | 2015-05-16 01:16 +0100 |
| Message-ID | <mailman.52.1431735384.17265.python-list@python.org> |
| In reply to | #90646 |
On 15/05/2015 13:35, Mark Lawrence wrote: > On 15/05/2015 04:58, Xiang Zhang wrote: >> Dear all, >> >> I am writing a code using Python now. >> >> I want to know how to find out values of all feasible x under >> constraints. >> >> x = [x_1, x_2, x_3,..., x_10] >> >> >> constraints: >> x_i = 0,1,2,3 or 4, where i=1,2,....10 >> x_1 + x_2 + x_3 +...+x_10 <= 15 >> >> How to find out all the feasible solutions x (domain of x) using >> python, like [0,0,0,0,0,0,0,0,0,0], [1,1,1,1,1,1,1,1,1,1] etc ? What >> should be the code? >> >> Any hint or help would be highly appreciated! >> >> Sincerely, >> >> Xiang Zhang >> > > There are several constraint libraries on pypi if you don't want to roll > your own. See for example > https://pypi.python.org/pypi/python-constraint/1.2 > Forgot to mention this http://numberjack.ucc.ie/ Maybe of general interest see also http://www.csplib.org/ http://www.hakank.org/constraint_programming_blog/ -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence
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