Creating sympy Matrices from columns
1
I'm trying to create a sympy Matrix by choosing columns from an existing Matrix (for calculating principal minors). At the moment I'm doing it like this:
>>> A = Matrix(3,5,[2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> l = [A[:,i].T for i in [2,3,0]]
>>> M = Matrix(l).T
>>> M
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
But this seems wasteful to me (especially the need to transpose twice. I don't know if this is time consuming). Is there a better way? Would there be a better way if i only need the determinant?
python matrix sympy
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
asked May 4 '17 at 8:01
pyrogenpyrogen
373
add a comment |
1
I'm trying to create a sympy Matrix by choosing columns from an existing Matrix (for calculating principal minors). At the moment I'm doing it like this:
>>> A = Matrix(3,5,[2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> l = [A[:,i].T for i in [2,3,0]]
>>> M = Matrix(l).T
>>> M
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
But this seems wasteful to me (especially the need to transpose twice. I don't know if this is time consuming). Is there a better way? Would there be a better way if i only need the determinant?
python matrix sympy
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
asked May 4 '17 at 8:01
pyrogenpyrogen
373
add a comment |
1
1
1
I'm trying to create a sympy Matrix by choosing columns from an existing Matrix (for calculating principal minors). At the moment I'm doing it like this:
>>> A = Matrix(3,5,[2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> l = [A[:,i].T for i in [2,3,0]]
>>> M = Matrix(l).T
>>> M
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
But this seems wasteful to me (especially the need to transpose twice. I don't know if this is time consuming). Is there a better way? Would there be a better way if i only need the determinant?
python matrix sympy
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
asked May 4 '17 at 8:01
pyrogenpyrogen
373
I'm trying to create a sympy Matrix by choosing columns from an existing Matrix (for calculating principal minors). At the moment I'm doing it like this:
>>> A = Matrix(3,5,[2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> l = [A[:,i].T for i in [2,3,0]]
>>> M = Matrix(l).T
>>> M
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
But this seems wasteful to me (especially the need to transpose twice. I don't know if this is time consuming). Is there a better way? Would there be a better way if i only need the determinant?
python matrix sympy
python matrix sympy
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
asked May 4 '17 at 8:01
pyrogenpyrogen
373
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
asked May 4 '17 at 8:01
pyrogenpyrogen
373
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
edited Nov 13 '18 at 5:02
Cœur
17.9k9107147
17.9k9107147
asked May 4 '17 at 8:01
pyrogenpyrogen
373
asked May 4 '17 at 8:01
pyrogenpyrogen
373
asked May 4 '17 at 8:01
pyrogenpyrogen
373
373
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
1
You can use [2, 3, 0] as index.
>>> A = Matrix(3, 5, [2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> A[:, [2,3,0]]
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
For lower version that does not support using list as a index, you can use Matrix.hstack:
>>> Matrix.hstack(*(A.col(i) for i in [2,3,0]))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
or Matrix.row_join:
>>> # from functools import reduce # For Python 3.x
>>> reduce(Matrix.row_join, (A.col(i) for i in [2,3,0]), Matrix(3,0,))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
This does not work for me. I get an IndexError: Invalid index a[[2, 3, 0]]. Do I have a wrong version (0.7.4.1)? or is this only possible with numpy matrices?
– pyrogen
May 12 '17 at 11:10
@pyrogen, I usedsympy 1.0
– falsetru
May 12 '17 at 16:06
@pyrogen, I updated the answer to include alternative approaches. (tested with sympy 0.7.4.1)
– falsetru
May 12 '17 at 16:23
great! it works. I didnt know about hstack
– pyrogen
May 17 '17 at 9:58
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
1
You can use [2, 3, 0] as index.
>>> A = Matrix(3, 5, [2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> A[:, [2,3,0]]
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
For lower version that does not support using list as a index, you can use Matrix.hstack:
>>> Matrix.hstack(*(A.col(i) for i in [2,3,0]))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
or Matrix.row_join:
>>> # from functools import reduce # For Python 3.x
>>> reduce(Matrix.row_join, (A.col(i) for i in [2,3,0]), Matrix(3,0,))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
This does not work for me. I get an IndexError: Invalid index a[[2, 3, 0]]. Do I have a wrong version (0.7.4.1)? or is this only possible with numpy matrices?
– pyrogen
May 12 '17 at 11:10
@pyrogen, I usedsympy 1.0
– falsetru
May 12 '17 at 16:06
@pyrogen, I updated the answer to include alternative approaches. (tested with sympy 0.7.4.1)
– falsetru
May 12 '17 at 16:23
great! it works. I didnt know about hstack
– pyrogen
May 17 '17 at 9:58
add a comment |
1
You can use [2, 3, 0] as index.
>>> A = Matrix(3, 5, [2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> A[:, [2,3,0]]
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
For lower version that does not support using list as a index, you can use Matrix.hstack:
>>> Matrix.hstack(*(A.col(i) for i in [2,3,0]))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
or Matrix.row_join:
>>> # from functools import reduce # For Python 3.x
>>> reduce(Matrix.row_join, (A.col(i) for i in [2,3,0]), Matrix(3,0,))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
This does not work for me. I get an IndexError: Invalid index a[[2, 3, 0]]. Do I have a wrong version (0.7.4.1)? or is this only possible with numpy matrices?
– pyrogen
May 12 '17 at 11:10
@pyrogen, I usedsympy 1.0
– falsetru
May 12 '17 at 16:06
@pyrogen, I updated the answer to include alternative approaches. (tested with sympy 0.7.4.1)
– falsetru
May 12 '17 at 16:23
great! it works. I didnt know about hstack
– pyrogen
May 17 '17 at 9:58
add a comment |
1
1
1
You can use [2, 3, 0] as index.
>>> A = Matrix(3, 5, [2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> A[:, [2,3,0]]
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
For lower version that does not support using list as a index, you can use Matrix.hstack:
>>> Matrix.hstack(*(A.col(i) for i in [2,3,0]))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
or Matrix.row_join:
>>> # from functools import reduce # For Python 3.x
>>> reduce(Matrix.row_join, (A.col(i) for i in [2,3,0]), Matrix(3,0,))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
You can use [2, 3, 0] as index.
>>> A = Matrix(3, 5, [2,3,4,1,34,23,12,54,5,0,0,0,3,4,5])
>>> A[:, [2,3,0]]
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
For lower version that does not support using list as a index, you can use Matrix.hstack:
>>> Matrix.hstack(*(A.col(i) for i in [2,3,0]))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
or Matrix.row_join:
>>> # from functools import reduce # For Python 3.x
>>> reduce(Matrix.row_join, (A.col(i) for i in [2,3,0]), Matrix(3,0,))
Matrix([
[ 4, 1, 2],
[54, 5, 23],
[ 3, 4, 0]])
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
edited May 12 '17 at 16:19
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
answered May 4 '17 at 8:14
falsetrufalsetru
246k34430427
246k34430427
This does not work for me. I get an IndexError: Invalid index a[[2, 3, 0]]. Do I have a wrong version (0.7.4.1)? or is this only possible with numpy matrices?
– pyrogen
May 12 '17 at 11:10
@pyrogen, I usedsympy 1.0
– falsetru
May 12 '17 at 16:06
@pyrogen, I updated the answer to include alternative approaches. (tested with sympy 0.7.4.1)
– falsetru
May 12 '17 at 16:23
great! it works. I didnt know about hstack
– pyrogen
May 17 '17 at 9:58
add a comment |
This does not work for me. I get an IndexError: Invalid index a[[2, 3, 0]]. Do I have a wrong version (0.7.4.1)? or is this only possible with numpy matrices?
– pyrogen
May 12 '17 at 11:10
@pyrogen, I usedsympy 1.0
– falsetru
May 12 '17 at 16:06
@pyrogen, I updated the answer to include alternative approaches. (tested with sympy 0.7.4.1)
– falsetru
May 12 '17 at 16:23
great! it works. I didnt know about hstack
– pyrogen
May 17 '17 at 9:58
This does not work for me. I get an IndexError: Invalid index a[[2, 3, 0]]. Do I have a wrong version (0.7.4.1)? or is this only possible with numpy matrices?
– pyrogen
May 12 '17 at 11:10
This does not work for me. I get an IndexError: Invalid index a[[2, 3, 0]]. Do I have a wrong version (0.7.4.1)? or is this only possible with numpy matrices?
– pyrogen
May 12 '17 at 11:10
@pyrogen, I used
sympy 1.0– falsetru
May 12 '17 at 16:06
@pyrogen, I used
sympy 1.0– falsetru
May 12 '17 at 16:06
@pyrogen, I updated the answer to include alternative approaches. (tested with sympy 0.7.4.1)
– falsetru
May 12 '17 at 16:23
@pyrogen, I updated the answer to include alternative approaches. (tested with sympy 0.7.4.1)
– falsetru
May 12 '17 at 16:23
great! it works. I didnt know about hstack
– pyrogen
May 17 '17 at 9:58
great! it works. I didnt know about hstack
– pyrogen
May 17 '17 at 9:58
add a comment |
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