z i$nSrSSKrSSKJr SSKJr SSKJr SSKJ r SSK J r SSK J r "S S \5rg) z Creating Sabre starting layouts.N) AnalysisPass) CouplingMap)TranspilerError) VF2Layout)Target)ErrorMapcX^\rSrSrSrS U4SjjrSrSrSrSr Sr S r U=r $) SabrePreLayoutaChoose a starting layout to use for additional Sabre layout trials. Property Set Values Written --------------------------- ``sabre_starting_layouts`` (``list[Layout]``) An optional list of :class:`~.Layout` objects to use for additional Sabre layout trials. **References:** [1] Henry Zou and Matthew Treinish and Kevin Hartman and Alexander Ivrii and Jake Lishman. "LightSABRE: A Lightweight and Enhanced SABRE Algorithm" `arXiv:2409.08368 `__ c>X lX0lX@lXPlX`l[ U[ 5(a&XlURR5Ul O SUlXl [TU]-5 g)aqSabrePreLayout initializer. The pass works by augmenting the coupling map with more and more "extra" edges until VF2 succeeds to find a perfect graph isomorphism. More precisely, the augmented coupling map contains edges between nodes that are within a given distance ``d`` in the original coupling map, and the value of ``d`` is increased until an isomorphism is found. Intuitively, a better layout involves fewer extra edges. The pass also optionally minimizes the number of extra edges involved in the layout until a local minimum is found. This involves removing extra edges and running VF2 to see if an isomorphism still exists. Args: coupling_map (Union[CouplingMap, Target]): directed graph representing the original coupling map or a target modelling the backend (including its connectivity). max_distance (int): the maximum distance to consider for augmented coupling maps. error_rate (float): the error rate to assign to the "extra" edges. A non-zero error rate prioritizes VF2 to choose original edges over extra edges. max_trials_vf2 (int): specifies the maximum number of VF2 trials. A larger number allows VF2 to explore more layouts, eventually choosing the one with the smallest error rate. call_limit_vf2 (int): limits each call to VF2 by bounding the number of VF2 state visits. improve_layout (bool): whether to improve the layout by minimizing the number of extra edges involved. This might be time-consuming as this requires additional VF2 calls. Raises: TranspilerError: At runtime, if neither ``coupling_map`` or ``target`` are provided. N) max_distance error_ratemax_trials_vf2call_limit_vf2improve_layout isinstancertargetbuild_coupling_map coupling_mapsuper__init__)selfrr rrrr __class__s j/home/james-whalen/.local/lib/python3.13/site-packages/qiskit/transpiler/passes/layout/sabre_pre_layout.pyrSabrePreLayout.__init__)sbR)$,,, lF + +&K $ > > @D DK ,  cBURc [S5eSnSnX0R::aURU5upE[ USUR UR S9nXVRS'URU5 SUR;aURSnOUS- nX0R::aMUS:afUbbUR(aURX5nSUR;aU/URS'gURSRU5 ggg) zRun the SabrePreLayout pass on `dag`. The discovered starting layout is written to the property set value ``sabre_starting_layouts``. Args: dag (DAGCircuit): DAG to create starting layout for. NzSSabrePreLayout requires coupling_map to be used with eitherCouplingMap or a Target.seed max_trials call_limitvf2_avg_error_maplayoutsabre_starting_layouts) rrr _add_extra_edgesrrr property_setrunr_minimize_extra_edgesappend)rdagstarting_layout cur_distance augmented_mapaugmented_error_mappass_s rr)SabrePreLayout.runas1    $!+   ///151F1F|1T .M.... E 7J  2 3 IIcN5---"'"4"4X"> A L///" !  ;"""&"<"O!!":;!!":;BB?S!< rc\[URR5n[5nURRR 5Ul[ U5n[ R"URRR5S5HupVURRXV5nSUs=:aU::dM/O M3SSUR- U-- nURXV5 URXV4U5 URXe5 URXe4U5 M X44$)zAugments the coupling map with extra edges that connect nodes ``distance`` apart in the original graph. The extra edges are assigned errors allowing VF2 to prioritize real edges over extra edges. r) lenrgraphrcopyr itertools combinations node_indicesdistanceradd_edge add_error) rr;nqaugmented_coupling_mapr0xydrs rr'SabrePreLayout._add_extra_edgess ""(( )!,'+'8'8'>'>'C'C'E$&rl**4+<+<+B+B+O+O+QSTUDA!!**10A1   1t#61"<= &//5#--qfjA&//5#--qfjAV&::rc&[5nUR5nUR5HbnXERSnXERSnURR Xg5S:dMFXg:aXg4OXv4nUR U5 Md U$)z6Returns the set of extra edges involved in the layout.rr)setget_virtual_bits two_qubit_opsqargsrr;add) rr,r%extra_edges_used virtual_bitsnodep0p1 extra_edges r_get_extra_edges_used$SabrePreLayout._get_extra_edges_useds5..0 %%'Djjm,Bjjm,B  ))"1A5)+bXrh  $$Z0 (  rc[U5n[USSURS9nURU5 URR SS5$)z5Checks if there is a layout for a given set of edges.rrr r%N)rrrr)r(get)rr,edgescmr1s r _find_layoutSabrePreLayout._find_layoutsF  "1t?R?RS #!!%%h55rcL/n[R"URRR 5S5H:upEURR XE5nUS:XdM(UR XE45 M< Un/nURX5n U (a[[U 55n U RU 5 URXU-[U 5-5n U cUR U 5 O+URX5R[U55n U nU (aMU$)zMinimizes the set of extra edges involved in the layout. This iteratively removes extra edges from the coupling map and uses VF2 to check if a layout still exists. This is reasonably efficiently as it only looks for a local minimum. r4r)r8r9rr6r:r;r+rPnextiterremoverVlist differencerE) rr,r- real_edgesr@rArB best_layoutextra_edges_necessaryextra_edges_unprocessed_set edge_chosenr%s rr*$SabrePreLayout._minimize_extra_edgess  **4+<+<+B+B+O+O+QSTUDA!!**10AAv!!1&)V & !#&*&@&@&V#)t$?@AK ' . .{ ;&&"77$?Z:[[F~%,,[9 /3.H.H.U.`.`-./+% )*),r)rrrrr rr)r4g?dNT) __name__ __module__ __qualname____firstlineno____doc__rr)r'rPrVr*__static_attributes__ __classcell__)rs@rr r s? $6p+TZ;*  6++rr )rir8qiskit.transpiler.basepassesrqiskit.transpiler.couplingrqiskit.transpiler.exceptionsr*qiskit.transpiler.passes.layout.vf2_layoutrqiskit.transpiler.targetrqiskit._accelerate.error_maprr rrrss-'528@+1H\Hr