Redefine subscripted assignment
A = subsasgn(A,S,B)
A = subsasgn(A,S,B) called by MATLAB® for
the syntax A(i) = B, A{i} = B,
or A.i = B when A is an object.
MATLAB uses the built-in subsasgn function
to interpret indexed assignment statements. Modify the indexed assignment
behavior of classes by overloading subsasgn in
the class.
Note
You must call subsasgn with an output argument. subsasgn does
not modify the object used in the indexing operation (the first input
argument). You must assign the output to obtain a modified object.
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Object used in indexing operation |
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Structure with two fields,
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Value being assigned (right side of assignment statement) |
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Result of the assignment statement, which is the modified object passed in as the first argument. If your implementation of a |
Argument values for the subsasgn for the
expression shown:
A(1:2,:) = B;
The syntax A(1:2,:) = B calls A
= subsasgn(A,S,B) where S is a structure
with S.type = '()' and S.subs = {1:2,':'}.
The colon character (':') indicates a colon used
as a subscript.
For the expression:
A{1:2} = B;The syntax A{1:2} = B calls A =
subsasgn(A,S,B) where S.type = '{}' and S.subs
= {[1 2]}.
For the expression:
A.field = B;
The syntax A.field = B calls A =
subsasgn(A,S,B) where S.type = '.' and S.subs
= 'field'.
For the expression:
A(1,2).name(3:5) = B;
Simple calls combine in a straightforward way for more complicated
indexing expressions. In such cases, length(S) is
the number of subscripting levels. For instance, A(1,2).name(3:5)
= B calls A = subsasgn(A,S,B) where S is
a 3-by-1 array of structures with the following values:
S(1).type = '()' | S(2).type = '.' | S(3).type = '()' |
S(1).subs = {1,2} | S(2).subs = 'name' | S(3).subs = {[3 4 5]} |
Within the subsasgn method defined by a class, MATLAB calls
the built-in subsasgn. Calling the built-in enables
you to use the default indexing behavior when defining specialized
indexing. For more information, see Built-In subsref and subsasgn Called in Methods.
In the assignment A(J,K,...) = B(M,N,...),
subscripts J, K, M, N,
and so on, can be scalar, vector, or arrays, when all the following
are true:
The number of subscripts specified for B,
excluding trailing subscripts equal to 1, does not exceed the value
returned by ndims(B).
The number of nonscalar subscripts specified for A equals
the number of nonscalar subscripts specified for B.
For example, A(5,1:4,1,2) = B(5:8) is valid because
both sides of the equation use one nonscalar subscript.
The order and length of all nonscalar subscripts specified
for A matches the order and length of nonscalar
subscripts specified for B. For example, A(1:4,3,3:9)
= B(5:8,1:7) is valid because both sides of the equation
(ignoring the one scalar subscript 3) use a 4-element
subscript followed by a 7-element subscript.