python (scipy): Resizing a sparse matrix

Question

I'm having trouble resizing a matrix - the set_shape function seems to have no effect:

>>> M
<14x3562 sparse matrix of type '<type 'numpy.float32'>'
   with 6136 stored elements in LInked List format>
>>> new_shape = (15,3562)
>>> M.set_shape(new_shape)
>>> M
<14x3562 sparse matrix of type '<type 'numpy.float32'>'
   with 6136 stored elements in LInked List format>

Anyone else come across this?

I also tried doing this by hand, i.e.

>>> M._shape = new_shape
>>> M.data = np.concatenate(M.data, np.empty((0,0), dtype=np.float32))

but that throws up an error:

*** TypeError: only length-1 arrays can be converted to Python scalars

or

>>> M.data = np.concatenate(M.data, [])
*** TypeError: an integer is required

For info:

Python 2.6.5 (r265:79063, Apr 16 2010, 13:57:41)
scipy 0.11.0.dev-03f9e4a

Fred Foo · Accepted Answer · 2012-03-08 17:15:15Z

5

If you just want to add a row of zeros at the end:

>>> M = sp.lil_matrix((14, 3562))
>>> sp.vstack([M, sp.lil_matrix((1, 3562))])
<15x3562 sparse matrix of type '<type 'numpy.float64'>'
        with 0 stored elements in COOrdinate format>

answered Mar 8, 2012 at 17:15

Fred Foo

365k80 gold badges765 silver badges852 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

tdc Over a year ago

Weirdly that gives me an error: row = sparse.lil_matrix((1,3562)) followed by sparse.vstack(M, row) gives *** NotImplementedError: adding a scalar to a CSC or CSR matrix is not supported

tdc Over a year ago

and before you ask M is definitely a lil matrix!

Fred Foo Over a year ago

@tdc: that's sparse.vstack([M, row]).

tdc Over a year ago

genius, thanks. I've been shaving yaks all afternooon with this one!!

Collectives™ on Stack Overflow

python (scipy): Resizing a sparse matrix

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related