Merge remote-tracking branch 'origin/flats_matroid' into develop

src/sage/matroids/advanced.py

@@ -17,7 +17,6 @@
         - :class:`CircuitClosuresMatroid <sage.matroids.circuit_closures_matroid.CircuitClosuresMatroid>`
         - :class:`BasisMatroid <sage.matroids.basis_matroid.BasisMatroid>`
         - :class:`FlatsMatroid <sage.matroids.flats_matroid.FlatsMatroid>`
-        - :class:`LatticeOfFlatsMatroid <sage.matroids.flats_matroid.LatticeOfFlatsMatroid>`
         - :class:`LinearMatroid <sage.matroids.linear_matroid.LinearMatroid>`
         - :class:`RegularMatroid <sage.matroids.linear_matroid.RegularMatroid>`
         - :class:`BinaryMatroid <sage.matroids.linear_matroid.BinaryMatroid>`
@@ -59,7 +58,7 @@
 from .circuits_matroid import CircuitsMatroid
 from .circuit_closures_matroid import CircuitClosuresMatroid
 from .basis_matroid import BasisMatroid
-from .flats_matroid import FlatsMatroid, LatticeOfFlatsMatroid
+from .flats_matroid import FlatsMatroid
 from .linear_matroid import LinearMatroid, RegularMatroid, BinaryMatroid, TernaryMatroid, QuaternaryMatroid
 from .utilities import setprint, newlabel, get_nonisomorphic_matroids, lift_cross_ratios, lift_map
 from . import lean_matrix

src/sage/matroids/basis_exchange_matroid.pxd

@@ -4,11 +4,10 @@ from .matroid cimport Matroid
 from .set_system cimport SetSystem
 
 cdef class BasisExchangeMatroid(Matroid):
-    cdef long _groundset_size, _matroid_rank, _bitset_size
+    cdef long _groundset_size, _bitset_size
     cdef bitset_t _current_basis, _inside, _outside, _input, _input2, _output, _temp
     cdef tuple _E
     cdef dict _idx
-    cdef frozenset _groundset
 
     cdef _bcount
     cdef _weak_invariant_var, _strong_invariant_var, _heuristic_invariant_var

src/sage/matroids/circuit_closures_matroid.pxd

@@ -1,9 +1,7 @@
 from sage.matroids.matroid cimport Matroid
 
 cdef class CircuitClosuresMatroid(Matroid):
-    cdef frozenset _groundset  # _E
-    cdef dict _circuit_closures  # _CC
-    cdef int _matroid_rank  # _R
+    cdef dict _circuit_closures
     cpdef frozenset groundset(self)
     cpdef int _rank(self, frozenset X)
     cpdef full_rank(self)

src/sage/matroids/circuits_matroid.pxd

@@ -2,8 +2,6 @@ from .matroid cimport Matroid
 from .set_system cimport SetSystem
 
 cdef class CircuitsMatroid(Matroid):
-    cdef frozenset _groundset
-    cdef int _matroid_rank
     cdef set _C  # circuits
     cdef dict _k_C  # k-circuits (k=len)
     cdef list _sorted_C_lens

src/sage/matroids/constructor.py

@@ -105,6 +105,7 @@
 # ****************************************************************************
 
 from itertools import combinations
+from sage.combinat.posets.lattices import FiniteLatticePoset
 from sage.matrix.constructor import Matrix
 from sage.structure.element import is_Matrix
 from sage.rings.integer_ring import ZZ
@@ -116,16 +117,10 @@
 import sage.matroids.basis_exchange_matroid
 from .rank_matroid import RankMatroid
 from .circuits_matroid import CircuitsMatroid
-from .flats_matroid import (FlatsMatroid, LatticeOfFlatsMatroid)
+from .flats_matroid import FlatsMatroid
 from .circuit_closures_matroid import CircuitClosuresMatroid
 from .basis_matroid import BasisMatroid
-from .linear_matroid import (
-    LinearMatroid,
-    RegularMatroid,
-    BinaryMatroid,
-    TernaryMatroid,
-    QuaternaryMatroid
-)
+from .linear_matroid import LinearMatroid, RegularMatroid, BinaryMatroid, TernaryMatroid, QuaternaryMatroid
 from .graphic_matroid import GraphicMatroid
 import sage.matroids.utilities
 
@@ -194,7 +189,7 @@ def Matroid(groundset=None, data=None, **kwds):
     - ``circuits`` -- The list of circuits of the matroid.
     - ``nonspanning_circuits`` -- The list of nonspanning circuits of the
       matroid.
-    - ``flats`` -- The dictionary or list of flats of the matroid.
+    - ``flats`` -- The dictionary, list, or lattice of flats of the matroid.
     - ``graph`` -- A graph, whose edges form the elements of the matroid.
     - ``matrix`` -- A matrix representation of the matroid.
     - ``reduced_matrix`` -- A reduced representation of the matroid: if
@@ -247,7 +242,6 @@ def Matroid(groundset=None, data=None, **kwds):
         :class:`BasisMatroid <sage.matroids.basis_matroid.BasisMatroid>`,
         :class:`CircuitsMatroid <sage.matroids.circuits_matroid.CircuitsMatroid>`,
         :class:`FlatsMatroid <sage.matroids.flats_matroid.FlatsMatroid>`,
-        :class:`LatticeOfFlatsMatroid <sage.matroids.flats_matroid.LatticeOfFlatsMatroid>`,
         :class:`CircuitClosuresMatroid <sage.matroids.circuit_closures_matroid.CircuitClosuresMatroid>`,
         :class:`LinearMatroid <sage.matroids.linear_matroid.LinearMatroid>`,
         :class:`BinaryMatroid <sage.matroids.linear_matroid.LinearMatroid>`,
@@ -343,32 +337,30 @@ def Matroid(groundset=None, data=None, **kwds):
 
         Strange things can happen if the input does not satisfy the circuit
         axioms, and these can be caught by the
-        :meth:`is_valid() <sage.matroids.matroid.Matroid.is_valid>` method. So
-        always check whether your input makes sense!
+        :meth:`is_valid() <sage.matroids.circuits_matroid.CircuitsMatroid.is_valid>`
+        method. So please check that your input makes sense!
 
         ::
 
             sage: M = Matroid('abcd', circuits=['ab', 'acd'])
             sage: M.is_valid()
             False
 
-    #.  Dictionary or list of flats:
+    #.  Flats:
 
         Given a dictionary of flats indexed by their rank, we get a
-        :class:`FlatsMatroid <sage.matroids.circuits_matroid.FlatsMatroid>`::
+        :class:`FlatsMatroid <sage.matroids.flats_matroid.FlatsMatroid>`::
 
             sage: M = Matroid(flats={0: [''], 1: ['a', 'b'], 2: ['ab']})
-            sage: M.is_valid()
+            sage: M.is_isomorphic(matroids.Uniform(2, 2)) and M.is_valid()
             True
             sage: type(M)
             <class 'sage.matroids.flats_matroid.FlatsMatroid'>
 
-        If instead we simply provide a list of flats, then we get a subclass
-        :class:`LatticeOfFlatsMatroid <sage.matroids.circuits_matroid.LatticeOfFlatsMatroid>`
-        of :class:`FlatsMatroid <sage.matroids.circuits_matroid.FlatsMatroid>`.
-        This class computes and stores the lattice of flats upon definition.
-        This can be time-consuming, but after it's done we benefit from some
-        faster methods (e.g., ``is_valid``)::
+        If instead we simply provide a list of flats, then the class computes
+        and stores the lattice of flats upon definition. This can be
+        time-consuming, but after it's done we benefit from some faster methods
+        (e.g., :meth:`is_valid() <sage.matroids.flats_matroid.FlatsMatroid.is_valid>`)::
 
             sage: M = Matroid(flats=['', 'a', 'b', 'ab'])
             sage: for i in range(M.rank() + 1):  # print flats by rank
@@ -379,7 +371,18 @@ def Matroid(groundset=None, data=None, **kwds):
             sage: M.is_valid()
             True
             sage: type(M)
-            <class 'sage.matroids.flats_matroid.LatticeOfFlatsMatroid'>
+            <class 'sage.matroids.flats_matroid.FlatsMatroid'>
+
+        Finally, we can also directly provide a lattice of flats::
+
+            sage: from sage.combinat.posets.lattices import LatticePoset
+            sage: flats = [frozenset(F) for F in powerset('ab')]
+            sage: L_M = LatticePoset((flats, lambda x, y: x < y))
+            sage: M = Matroid(L_M)
+            sage: M.is_isomorphic(matroids.Uniform(2, 2)) and M.is_valid()
+            True
+            sage: type(M)
+            <class 'sage.matroids.flats_matroid.FlatsMatroid'>
 
     #.  Graph:
 
@@ -846,6 +849,8 @@ def Matroid(groundset=None, data=None, **kwds):
             key = 'matroid'
         elif isinstance(data, str):
             key = 'lex'
+        elif isinstance(data, dict) or isinstance(data, FiniteLatticePoset):
+            key = 'flats'
         elif data is None:
             raise TypeError("no input data given for Matroid()")
         else:
@@ -920,11 +925,10 @@ def Matroid(groundset=None, data=None, **kwds):
                 for i in data:
                     for F in data[i]:
                         groundset.update(F)
-                M = FlatsMatroid(groundset=groundset, flats=data)
-            else:
+            else:  # iterable of flats (including lattice)
                 for F in data:
                     groundset.update(F)
-                M = LatticeOfFlatsMatroid(groundset=groundset, flats=data)    
+        M = FlatsMatroid(groundset=groundset, flats=data)
 
     # Graphs:
     elif key == 'graph':

src/sage/matroids/flats_matroid.pxd

@@ -1,29 +1,25 @@
 from .matroid cimport Matroid
-from sage.combinat.posets.lattices import FiniteLatticePoset
 from .set_system cimport SetSystem
 
 cdef class FlatsMatroid(Matroid):
-    cdef frozenset _groundset  # _E
-    cdef int _matroid_rank  # _R
     cdef dict _F  # flats
+    cdef object _L  # lattice of flats
     cpdef frozenset groundset(self)
+
     cpdef int _rank(self, frozenset X)
-    cpdef full_rank(self)
     cpdef frozenset _closure(self, frozenset X)
     cpdef bint _is_closed(self, frozenset X)
 
+    cpdef full_rank(self)
+
     # enumeration
     cpdef SetSystem flats(self, long k)
+    cpdef list whitney_numbers(self)
     cpdef list whitney_numbers2(self)
 
     # isomorphism and relabeling
     cpdef _is_isomorphic(self, other, certificate=*)
-    cpdef relabel(self, mapping)
+    cpdef Matroid relabel(self, mapping)
 
     # verification
     cpdef bint is_valid(self)
-
-cdef class LatticeOfFlatsMatroid(FlatsMatroid):
-    cdef object _L  # lattice_of_flats
-    cpdef list whitney_numbers(self)
-    cpdef bint is_valid(self)