I am now trying to speed up Permutation.to_matrix, which is meanwhile one of the worst offenders in my application. After some profiling I found the following, which is quite a mystery to me. Apparently it is possible that importing a module in a method costs a significant amount of time!
QUESTION: is this an oversight or is there a good reason to import modules
in a relatively fundamental method like MatrixSpace.matrix?
(I checked, moving out the first import makes the whole thing
(Permutation.to_matrix()) 10% faster. I'm not saying that this is huge,
but it seems like a significant improvement to me. Unfortunately, the
second module cannot be easily moved out, because of an import loop)
This is #23870
Martin
sage: l = [pi for pi in Permutations(8)]
sage: %lprun -f Permutation.to_matrix -f MatrixSpace.matrix [pi.to_matrix()
for pi in l]
Timer unit: 1e-06 s
Total time: 41.8048 s
File:
/home/martin/sage-develop/local/lib/python2.7/site-packages/sage/matrix/matrix_space.py
Function: matrix at line 1354
Line # Hits Time Per Hit % Time Line Contents
==============================================================
1354 def matrix(self, x=0,
coerce=True, copy=True):
...
1493 362880 2800013 7.7 6.7 if x is None or
isinstance(x, (int, integer.Integer)) and x == 0:
1494 if
self._copy_zero: # faster to copy than to create a new one.
1495 return
self.zero_matrix().__copy__()
1496 else:
1497 return
self.__matrix_class(self, None, False, False)
1498 362880 2344112 6.5 5.6 if isinstance(x,
(int, integer.Integer)) and x == 1:
1499 return
self.identity_matrix().__copy__()
1500 362880 1577558 4.3 3.8 m, n, sparse =
self.__nrows, self.__ncols, self.__is_sparse
1501 362880 1462412 4.0 3.5 if
matrix.is_Matrix(x):
1502 if x.parent()
is self:
1503 if
x.is_immutable():
1504 return
x
1505 else:
1506 return
x.__copy__()
1507 else:
1508 if
x.nrows() == m and x.ncols() == n:
1509 if
(x.base_ring() == self.base_ring()
1510
and x.is_sparse() and not sparse):
1511 #
If x is sparse and large, calling x.dense_matrix()
1512 #
is much faster than calling x.list(). See #20470.
1513
return x.dense_matrix()
1514 x =
x.list()
1515 else:
1516 raise
ValueError("a matrix from %s cannot be converted to "
1517
"a matrix in %s!" % (x.parent(), self))
1518 362880 5492940 15.1 13.1 from
sage.groups.matrix_gps.group_element import \
1519
is_MatrixGroupElement
1520 362880 4978054 13.7 11.9 from
sage.modular.arithgroup.arithgroup_element import \
1521
ArithmeticSubgroupElement
1522 362880 2613184 7.2 6.3 if
is_MatrixGroupElement(x) or isinstance(x, ArithmeticSubgroupElement):
1523 return
self(x.matrix(), copy=False)
1524 362880 2036306 5.6 4.9 if isinstance(x,
(types.GeneratorType,)):
1525 x = list(x)
1526 362880 1226969 3.4 2.9 if not sparse and
isinstance(x, dict):
1527 x =
dict_to_list(x, m, n)
1528 coerce = True
1529 copy = False
1530 362880 1354039 3.7 3.2 MC =
self.__matrix_class
1531 362880 2139861 5.9 5.1 if isinstance(x,
(list, tuple)) and x:
1532 if len(x) ==
m: # Try unpacking elements
1533 unpacked =
True
1534 new_x = []
1535 for v in x:
1536 l =
len(new_x)
1537 try:
1538
from sage.structure.element import is_Vector
1539 if
isinstance(v, (list, tuple)) or is_Vector(v):
1540
# The isinstance check should prevent the "flattening"
1541
# of v if v is an iterable but not meant to be
1542
# iterated (e.g., an element of a combinatorial free
1543
# module).
1544
new_x.extend(v)
1545
else:
1546
raise TypeError
1547 if
len(new_x) - l != n:
1548
raise TypeError
1549 except
TypeError:
1550
unpacked = False
1551 if
unpacked:
1552 try:
1553 if
sparse:
1554
return MC(self, list_to_dict(new_x, m, n),
1555
copy=False, coerce=coerce)
1556
else:
1557
return MC(self, new_x, copy=False, coerce=coerce)
1558 except
(TypeError, ValueError):
1559
pass
1560 if len(x) != m
* n:
1561 raise
TypeError("cannot construct an element of {} from {}!"
1562
.format(self, x))
1563 if sparse:
1564 x =
list_to_dict(x, m, n)
1565 copy =
False
1566 362880 13779340 38.0 33.0 return MC(self, x,
copy=copy, coerce=coerce)
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/d/optout.
