Error when running G= graph(s,t) in matlab
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Ahmad Aseeri
el 1 de Abr. de 2017
Comentada: lol
el 10 de Nov. de 2021
I want to calculate L = laplacian(G) from a graph dataset. I imported the dataset, from here , which contains two columns as shown below:
# Nodes: 3997962 Edges: 34681189
# FromNodeId ToNodeId
0 1
0 2
0 31
0 73
0 80
0 113619
0 2468556
0 2823829
0 2823833
0 2846857
0 2947898
0 3011654
0 3701688
0 3849377
0 4036524
0 4036525
0 4036527
0 4036529
0 4036531
0 4036533
0 4036534
0 4036536
0 4036537
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
To do so, I need to find G first so I use G = graph(FromNodeId, ToNodeId). When I did that, I got this error:
>> G = graph(fromNodeId,toNodeId)
Error using matlab.internal.graph.MLGraph
Source must be a dense double array of node indices.
Error in matlab.internal.graph.constructFromEdgeList (line 125)
G = underlyingCtor(double(s), double(t), totalNodes);
Error in graph (line 264)
matlab.internal.graph.constructFromEdgeList(...
I don't know why! Can I get a solution of that? Thank you.
2 comentarios
Respuesta aceptada
Steven Lord
el 2 de Abr. de 2017
Indices in MATLAB start at 1, not 0. Try adding 1 to your index vectors.
Más respuestas (1)
lol
el 10 de Nov. de 2021
THIS IS MY CODE:
filename = 'TABLA_AF1';
s = xlsread(filename,'A2:A25');
t = xlsread(filename,'B2:B25');
weights = xlsread(filename,'C2:C25');
G = graph(s,t,weights);
p = plot(G,'EdgeLabel',G.Edges.Weight);
[T,pred] = minspantree(G);
highlight(p,T)
AND THIS IS MY BASE DATA:
Nodo Inicial Nodo Final Distancia
A B 2
A E 16
A C 3
C F 3
C I 12
F E 7
F I 9
F H 6
I H 14
E H 2
E G 4
B E 8
B D 11
D E 2
D G 5
D J 7
G J 1
G L 6
H G 3
J L 12
H L 17
I K 7
H K 9
K L 17
AND I GET THIS ERROR:
Error using matlab.internal.graph.constructFromEdgeList (line 249)
Weight must have as many elements as edge list or be a scalar.
Can you tell me why please?
12 comentarios
Walter Roberson
el 10 de Nov. de 2021
filename = 'TABLA_AF1.xlsx';
[~, s] = xlsread(filename,'A2:A25');
[~, t] = xlsread(filename,'B2:B25');
weights = xlsread(filename,'C2:C25');
G = graph(s,t,weights);
p = plot(G,'EdgeLabel',G.Edges.Weight);
[T,pred] = minspantree(G);
highlight(p,T)
When you use xlsread() then the first output is always purely numeric. But you are trying to read a text column for s and t, and the numeric interpretation of those is all NaN. It happens that xlsread() trims out leading and trailing NaN columns and rows, so the column of NaN gets trimmed away entirely leaving you with empty entries for s and t.
My adjusted code here uses the second output instead, which is the text entries.
You would be better of using readtable(), which is able to automatically detect the data type of inputs.
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