Access value in cell arrays

A{1,1}.str = 1;
A{2,1}.str = 2;
... (so on)
A{10,1}.str = 10;
Can I say:
B = A{:,1}.str;
so that:
B=[1 2 3 4 5 6 7 8 9 10];
Thanks very much

2 commentaires

per isakson
per isakson le 29 Juin 2013
Is A supposed to be a cell arrays of structures?
A field named "str" holding a numerical value isn't that confusing?
TN
TN le 29 Juin 2013
Yes... A is a cell arrays. Each cell array is a structure.
'str' is just a name. It does not mean to be a string. Sorry for the confusion.

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 Réponse acceptée

per isakson
per isakson le 29 Juin 2013
Modifié(e) : per isakson le 29 Juin 2013

3 votes

What you look for can be achieved with cellfun, see below.
Indexing like C{:}.field is not supported (AFAIK).
The script
S1.field=1;
S2.field=2;
S3.field=3;
C = { S1, S2, S3 };
C{1}.field
C{2}.field
C{3}.field
C{:}.field
returns
ans =
1
ans =
2
ans =
3
Bad cell reference operation.
And
vec = cellfun( @(S) S.field, C, 'uni', true )
returns
ans =
1 2 3
.
EDIT
The single command with cellfun is justified in case the cells of the cell array contain structures with only some fields in common.
Example:
S1.field=1;
S2.field=2;
S3.field=3;
S1.field1=1;
S2.field2=2;
S3.field3=3;
C = { S1, S2, S3 };
vec = cellfun( @(S) S.field, C, 'uni', true )
returns
vec =
1 2 3

4 commentaires

TN
TN le 29 Juin 2013
Thanks for your response. I am looking for a single command like the way Matlab handling the normal matrix array instead of using the "for" loop.
Matt J
Matt J le 29 Juin 2013
per gave you a single command solution
vec = cellfun( @(S) S.field, C, 'uni', true )
TN
TN le 29 Juin 2013
Thanks very much, Per and Matt. That's it. Sorry... somehow i didn't see the few last lines from "Per". You are all genious!
Matt J
Matt J le 29 Juin 2013
You can Accept-click per's Answer, then, since that was what you were looking for.

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Plus de réponses (2)

Matt J
Matt J le 29 Juin 2013
Modifié(e) : Matt J le 29 Juin 2013

1 vote

No. You can do this instead
A(1).str = 1;
A(2).str = 2;
...
A(10).str = 10;
B=[A(:).str]

3 commentaires

TN
TN le 29 Juin 2013
Hi Matt, Thanks for your response... but my problem is when A is a cell "{}" array (not a matrix "()" array).
Matt J
Matt J le 29 Juin 2013
It would not make sense to hold structures having the same fields inside cells. It just makes them harder to get to (as you've discovered).
per isakson
per isakson le 29 Juin 2013
Modifié(e) : per isakson le 29 Juin 2013
I agree.
However, for some reason the cell array may contain structures with only some fields in common.

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James Tursa
James Tursa le 29 Juin 2013

1 vote

Another variation:
x = [A{:,1}];
B = [x.str];

2 commentaires

TN
TN le 29 Juin 2013
Yes... thanks very much, James. Your solution works great for me too!
Matt J
Matt J le 30 Juin 2013
TN, if James solution works for you, there is really no reason to be carrying around A. You may as well just use x. As per said, it might make sense if A{i} were structs with different fields, but James' approach will not work if that is the case.

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