After a call to thisįunction, the graph cannot be modified, and therefore no more nodes can be Nodes as possible until cycles block more progress. Get_ready() can still be used to obtain as many Is detected, CycleError will be raised, but Mark the graph as finished and check for cycles in the graph. Raises ValueError if called after prepare(). Provided before is included among predecessors it will be automaticallyĪdded to the graph with no predecessors of its own. Provided) or to provide a dependency twice. It is possible to add a node with no dependencies ( predecessors is not If called multiple times with the same node argument, the set ofĭependencies will be the union of all dependencies passed in. Both the node and allĮlements in predecessors must be hashable. done ( node ) add ( node, * predecessors ) ¶Īdd a new node and its predecessors to the graph. After calling 'done()', we loop back to call 'get_ready()' # again, so put newly freed nodes on 'task_queue' as soon as # logically possible. # The definition of 'is_active()' guarantees that, at this point, at # least one node has been placed on 'task_queue' that hasn't yet # been passed to 'done()', so this blocking 'get()' must (eventually) # succeed. put ( node ) # When the work for a node is done, workers put the node in # 'finalized_tasks_queue' so we can get more nodes to work on. get_ready (): # Worker threads or processes take nodes to work on off the # 'task_queue' queue. is_active (): for node in topological_sorter. Topological_sorter = TopologicalSorter () # Add nodes to 'topological_sorter'. In the general case, the steps required to perform the sorting of a given Have edges that point to the value in the key). Representing a directed acyclic graph where the keys are nodes and the valuesĪre iterables of all predecessors of that node in the graph (the nodes that If the optional graph argument is provided it must be a dictionary Ordering is possible if and only if the graph has no directed cycles, that Ordering is just a valid sequence for the tasks. One task must be performed before another in this example, a topological Represent tasks to be performed, and the edges may represent constraints that For instance, the vertices of the graph may Provides functionality to topologically sort a graph of hashable nodes.Ī topological order is a linear ordering of the vertices in a graph such thatįor every directed edge u -> v from vertex u to vertex v, vertex u comesīefore vertex v in the ordering. If you need to export these, copy them into into custom properties with IGEdgeMap and IGVertexMap.Graphlib - Functionality to operate with graph-like structures ¶Ĭlass graphlib. IGExport will not include Mathematica-specific properties such as VertexStyle or VertexCoordinates. Notice the correct XML schema and the appropriate attribute types ( string and double). Here's what IGraph/M's IGExport function produces: IGExportString No other software than Mathematica will read this, so it's rather useless. It exports vertex coordinates as List, again put in a string. Even if the target software has a feature to convert string attributes into numbers, it will probably trip up on this `. Moreover, they will have a ` sign appended. Some software is forgiving, but your number will still come out as strings. string would be valid, but String is not. Here's what Export produces: ExportStringĭoes not specify the schema, so about half of the software out there does not even recognize this as GraphML.Įverything has attr.type='String'. You do not need to do anything else than add the properties to the graph before export.Įxample: "Alice"], Property}, This is why IGraph/M includes a separate GraphML exporter. The GraphML specification is quite clear about what data types are allowed and how they should be stored. Even those that do read it, often cannot use the properties because they are in the form of Mathematica expressions converted into strings. Many other systems will plainly refuse to read Mathematica-written GraphML. Mathematica does not produce standards compliant GraphML files.
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