MATLAB: String cell array inside a graph

Question

Say I have this:

C = {'a';'b';'c';'d';'e'}; 
s = [1 1 2 3 1];
t = [2 2 3 4 4];
G = graph(s,t);
G.Edges.Label = C;

With the following two commands I would expect to get the same output, but I get different, why with the second comand only one output is given?

C{[2 3]}
ans =
    'b'
ans =
    'c'
G.Edges.Label{[2 3]}
ans =
    'b'

Answer 1

I'm surprise no one give you get an answer. There is some subttle internal working needed to be explained.

The syntax

C{[2 3]}

returns a comma list. No function is called.

The second command

G.Edges.Label{[2 3]}

call a graph method (probably an overloaded subsref) and it returns on the LHS multiple output IF LHS it's provided. If not the default LHS and Matlab ANS (single "variable").

However if users provide 2 LHS they'll get them.

>> [bb,cc] = G.Edges.Label{[2 3]}
bb =
    'b'
cc =
    'c'
>> 

This behavior is very similar to any multiple-output function such as

>> [a,b]=meshgrid(1:3,1:2) % Get 2 LHSs
a =
     1     2     3
     1     2     3
b =
     1     1     1
     2     2     2
>> meshgrid(1:3,1:2) % get only the first LHS 
ans =
     1     2     3
     1     2     3

To digest all that think about the following result

 >> G.Edges.Label([2 3]) % parenthesis
ans =
  2×1 cell array
    {'b'}
    {'c'}
>> ans{:}
ans =
    'b'
ans =
    'c'
>>