temporarily remove an edge from the graph

[Srirama Bhamidipati]

Hi,

I was wonder what is a good way to remove an edge agent from the graph calculations temporarily ? The removal is based on a threshold value of an attribute of the edge. If the attribute regains it value below a threshold value, i would like that it is reconsidered in the graph calculations. 

I checked "remove", it shows a way to remove items from a list, but I do not know how to add an agent  back to the graph.

regards,

Srirama

[Patrick Taillandier]

Hi,

maybe, the simplest way is to do a copy of your graph:

graph g <- generate_complete_graph(nodeSpecy,edgeSpecy,net_size,false);

graph g_c <- copy(g);

remove edge: one_of (g_c.edges) from: g_c;

cheers,

Patrick

2014-04-29 12:45 GMT+02:00 Srirama Bhamidipati <b.sr...@gmail.com>:

Hi,

I was wonder what is a good way to remove an edge agent from the graph calculations temporarily ? The removal is based on a threshold value of an attribute of the edge. If the attribute regains it attribute value below a threshold value, i would like that it is reconsidered in the graph calculations. 

I checked "remove", it shows a way to remove items from a list, but I do not know how to add an agent  back to the graph.

regards,

Srirama

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[Srirama Bhamidipati]

Thank you Patrick, but if I remove, how do I add it back ? at the same place, same connections as before. For example, when the edge is taken off, traffic cannot move along it. Later when fixed, traffic can move on it. 

[Alexis Drogoul]

An option in this case could be to leave your graph intact and change the weight of the edge to a very large number.

Le 29 avr. 2014 à 18:39, Srirama Bhamidipati <b.sr...@gmail.com> a écrit :

> Thank you Patrick, but if I remove, how do I add it back ? at the same place, same connections as before. For example, when the edge is taken off, traffic cannot move along it. Later when fixed, traffic can move on it.
>

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[Patrick Taillandier]

You can add and remove edges and nodes quite easily in a graph:

add node: a_node to: my_graph;

add edge: node_s::node_t to: my_graph;

remove node: a_node from: my_graph;

remove edge: node_s::node from: my_graph;

There are also some specific operators: add_node and add_edge

Cheers, 

Patrick

PS : the solution of Alexis is good as well

2014-04-29 13:39 GMT+02:00 Srirama Bhamidipati <b.sr...@gmail.com>:

Thank you Patrick, but if I remove, how do I add it back ? at the same place, same connections as before. For example, when the edge is taken off, traffic cannot move along it. Later when fixed, traffic can move on it. 

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[Philippe Caillou]

Hi,

A related stupid quick question I could'nt answer: how do you change the weight of an edge?

Sorry for the topic-intrusion :)

Philippe

[Alexis Drogoul]

Hi,

I think, but I maybe wrong as I havent touched the graphs for a long time, that something like

g <- g with_weights([edge::w1, edge2::w2]);


should work.

Alexis

[Srirama Bhamidipati]

Oki I will try the options. 

Weight can be changed with the as_map operator mapping each edge  to a variable and then using the with_weights as Alexis suggested. I think there is tutorial

[Srirama Bhamidipati]

I think I should use the visible bool for a visual effect while in the background I should increase the weight of an edge. I will try. 

Thanks

Srirama

[Patrick Taillandier]

To change the weight, as Alexis said, you can use the "graph with_weights weights_map" operator.

The as_map operator is usefull when you need to change the weights of all the edges ;) .

g <- g with_weights([edge::w1, edge2::w2]); // change only the weights of edge1 and edge2

g <- g with_weights(road as_map (each::each.shape.perimeter * coeff)); // change the weights of all the road edges.

2014-04-29 14:05 GMT+02:00 Srirama Bhamidipati <b.sr...@gmail.com>:

Oki I will try the options. 

Weight can be changed with the as_map operator mapping each edge  to a variable.

[Philippe Caillou]

thank you!