Testing if an object is a matrix

Some time ago, to test if A is a matrix, I just used:

from sage.matrix.matrix import is_Matrix
if is_Matrix(A):
    ...

But this is now deprecated. What should I use instead?

2 Answers

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Emmanuel Charpentier
7057 ●6 ●46 ●137

Alternative :

sage: import_statements("is_Matrix")
from sage.structure.element import is_Matrix

HTH,

It's not really the function that was deprecated, but the module it was in.

The same function can now be imported from a different module.

To figure out the new import, one can have a look at

and click on the commit id in the "Branch" field to see the replacements that were made when the module was deprecated.

This is the new import:

from sage.structure.element import is_Matrix

How to figure all that out from scratch:

try the initial import:

sage: from sage.matrix.matrix import is_Matrix

then look at the source code of isMatrix:
```
sage: is_matrix??
```
this tells you everything happens in the file .../sage/matrix/matrix.pyx
in a text editor, open the file <path_to_sage_root_folder>/src/sage/matrix/matrix.pyx
in this file there is a note about deprecation and a reference to Sage Trac ticket 24096
then see above.

Simpler way to test if something is a matrix:

sage: A = matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
sage: isinstance(A, sage.structure.element.Matrix)
True

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