Comma-separated assignment to a table variable

2026 6 19
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更新时间：2026 6 19
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The code below tests assignment by comma-separated expansion to a cell array in 3 different scenarios. In the specific case when the cell array X is the variable of a table, it fails. Why is that?
X=cell(1,3);
S.X=X;
T=table(X);
[X{:}]=deal(1,2,3) %Case (1) : works fine
X = 1×3 cell array
{[1]} {[2]} {[3]}
[S.X{:}]=deal(1,2,3) %Case (2) : works fine
S = struct with fields:
X: {[1] [2] [3]}
[T.X{:}]=deal(1,2,3) %Case (3) : fails
Error using deal (line 37)
The number of outputs should match the number of inputs.

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Stephen23
Stephen23 29 minutes 前
Table overloads both subsref and subsasgn. Its indexing is nothing like any other class.
Paul
Paul about 5 hours 前
移动：Paul about 4 hours 前
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Ran in:
Why does the second call to deal result in three copies of the same displayed output?
X = cell(1,3);
T = table(X);
[X{:}] = deal(1,2,3)
X = 1×3 cell array
{[1]} {[2]} {[3]}
[T.X{1},T.X{2},T.X{3}] = deal(1,2,3)
T = table
X _______________________ {[1]} {[2]} {[3]}
T = table
X _______________________ {[1]} {[2]} {[3]}
T = table
X _______________________ {[1]} {[2]} {[3]}
Matt J
Matt J about 4 hours 前
Table overloads both subsref and subsasgn.
Does that explain why comma-separated assignment would not be supported?
Matt J
Matt J about 3 hours 前
编辑：Matt J about 3 hours 前
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Ran in:
Why does the second call to deal result in three copies of the same displayed output?
@Paul It is normal for unsuppressed output of CSL assignment to make nargout displays if it thinks the outputs are separate and unrelated variables, e.g.,
[a,b]=deal(1,2)
a = 1
b = 2
When you assign to separately indexed regions of the same variable, it apparently cannot tell they are related,
[X{1},X{2}] = deal(4,5)
X = 1×2 cell array
{[4]} {[5]}
X = 1×2 cell array
{[4]} {[5]}
as distinct from,
[X{1:2}]=deal(6,7)
X = 1×2 cell array
{[6]} {[7]}

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回答（1 个）

dpb
dpb about 5 hours 前
编辑：dpb about 5 hours 前
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As @Stephen23 notes, table addressing is its own animal...
The table is a one-row cell array in one vairable so it can be assigned directly as a cell can be...
X=cell(1,3);
T=table(X)
T = table
X ____________________________________________ {0×0 double} {0×0 double} {0×0 double}
T.X={1 2 3}
T = table
X _______________________ {[1]} {[2]} {[3]}
No need for deal() here as the dot-X notation returns the cell array in its entirety. Of course, in a table cell, it can contain anything any other cell can
T.X(1:2)={1 2};
T.X(3)={'Fred Flintstone'}
T = table
X _____________________________________ {[1]} {[2]} {'Fred Flintstone'}
T.X
ans = 1×3 cell array
{[1]} {[2]} {'Fred Flintstone'}

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Matt J
Matt J
about 13 hours 前

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Matt J
Matt J
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