Assign Multiple Variables

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Zach
Zach 2011-9-28
评论： Walter Roberson 2023-4-15
I have a array for example [1,2,3,4]. I want to assign a variable to each number in the array such that a=1, b=2, c=3, and d=4. I know I can do each one separately but I want to know if it is possible to this in one line.
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Image Analyst
Image Analyst 2011-9-29
Kind of reminded me of the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F though I'm not saying you don't have a valid reason for doing that - you may well have.

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采纳的回答

Walter Roberson
Walter Roberson 2011-9-28
It is not possible in one statement. It is possible in two statements, which you could combine on one line.
t = num2cell([1,2,3,4]);
[a,b,c,d] = deal(t{:});
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Fangjun Jiang
Fangjun Jiang 2023-4-14
Ran in:
t = num2cell([1,2,3,4]);
[a,b,c,d] = deal(t{:})
a = 1
b = 2
c = 3
d = 4
[a,b,c,d] = t{:}
a = 1
b = 2
c = 3
d = 4
Walter Roberson
Walter Roberson 2023-4-15
Ran in:
Back in 2011 it was not possible in one statement, at least not without an inline subsref(). A few years ago, however, a hack became available:
[a,b,c,d] = struct('x', num2cell([1,2,3,4])).x
a = 1
b = 2
c = 3
d = 4

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更多回答（4 个）

Raziman Thottungal Valapu
It is now possible to do this in one line cleanly
[a,b,c] = deal(1, "test", [1:5])
Gives me
a =
1
b =
"test"
c =
1 2 3 4 5
As expected
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Stephen23
Stephen23 2020-10-1
@Raziman Thottungal Valapu: no, that is not what the question is about. The question specifies that there is only one input array, but your code uses multiple separate inputs to deal. Not the same thing at all.

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Jeff Miller
Jeff Miller 2018-8-15
matsplit does this.
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Brent F
Brent F 2021-6-19
Much cleaner than deal(a(1), a(2), a(3), a(4), ...)

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Viktor
Viktor 2018-9-1
编辑：Viktor 2018-9-1
The one-liner I have been using is the following:
[a,b,c,d] = feval(@(x) x{:}, num2cell([1,2,3,4]));
(Don't claim it is my original idea, just felt it belongs to this thread. If it is posted elsewhere feel free to link it.)
  2 个评论
Daniel Birch
Daniel Birch 2018-9-12
Additionally, you can replace num2cell with any cell array of the right size, even one containing multiple data types. For example,
[a,b,c,d] = feval(@(x) x{:}, {rand(2), 5, 'hello', pi});
a
a =
0.9502 0.4387
0.0344 0.3816
b
b =
5
c
c =
hello
d
d =
3.1416
Stephen23
Stephen23 2018-9-12
编辑：Stephen23 2018-9-12
That is just subsref wrapped up in an anonymous function, which is then called by feval.
Here it is with subsref called directly:
>> [a,b,c,d] = subsref({rand(2), 5, 'hello', pi}, substruct('{}',{':'}))
a =
0.103676 0.814128
0.208758 0.092132
b = 5
c = hello
d = 3.1416

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Dan Erwin
Dan Erwin 2023-4-14
编辑：Walter Roberson 2023-4-14
The thing we are trying to do is emulate the very useful Python idiom e.g.
a,b,c,d = [1,2,3,4]
In Matlab, if you create a function assignList.m as follows:
function varargout = assignList( inputArray )
for i = 1:length( inputArray)
varargout{i} = inputArray(i);
end
end
then you can do for example
[a,b,c,d] = assignList( [1,2,3,4] )
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Fangjun Jiang
Fangjun Jiang 2023-4-14
@Stephen23, not with array input directly. See my comments at the answer by @Walter Roberson. My point is that this funciton is uncessary. Plus, I can't resist the "Deal or No deal" pun, now that I realized it.
Dan Erwin
Dan Erwin 2023-4-15
I would not have written my post if I had noticed the earlier answer which recommended the contributed function matsplit, which is similar to mine but is more flexible when using multidimensional arrays.

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