Accessing elements of lists within lists

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Aleem Andrew 2020-10-8

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/608723-accessing-elements-of-lists-within-lists

评论： Stephen23 2020-10-9

I have created a list which contains several lists in the following code.

a = [{'poh',3,4},{'v',5}]
a=[{'poh',3,4},{'v',5}]
a =
 1×5 cell array
 {'poh'}    {[3]}    {[4]}    {'v'}    {[5]}

Matlab interprets the elements as cells, but they should be treated as strings or integers/floats. Also, I want a(1) to equal {'poh',3,4} not 'poh' so elements within the sublist can be accessed by referencing it, for example, a(1)(2) = 3. Does anyone have suggestions regarding how this can be done?

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Walter Roberson 2020-10-9

Matlab interprets the elements as cells, but they should be treated as strings or integers/floats.

You are being confused by the display format that MATLAB uses to emphasize that you are dealing with a cell.

 1×5 cell array
 {'poh'}    {[3]}    {[4]}    {'v'}    {[5]}

is saying that a(1) is {'pho'}, which is correct: when you use () indexing on a cell array, you get back a cell array rather than the contents.

There were a lot of releases in the past where it would have presented the output as

'pho' [3] [4] 'v' [5]

which is just a choice of formatting.

The display is not telling you that a{1} is {'pho'} but rather that a(1) is {'pho'}

Stephen23 2020-10-9

"I have created a list which contains several lists ..."

MATLAB does not have "list" class. What you show is one single cell array formed by concatenating two cell arrays together (because the square brackets [] are a concatenation operator, not a "list" operator (which does not exist)).

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Answer 1

Mohammad Sami 2020-10-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/608723-accessing-elements-of-lists-within-lists#answer_509079

In Matlab cell arrays are the only type that can store heterogeneous data.

Just change the outside [] to {} if you want to have nested cell arrays.

a={{'poh',3,4},{'v',5}}
a{1}{2} 

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Aleem Andrew 2020-10-9

编辑：Aleem Andrew 2020-10-9

Thanks for your answer Is there a way to perform operations on the elements or compare their values, for example, to add element 2 to element 3 by typing something like a{1}{2}+a{1}{3} which should output the integer/double 7? And a{1}{1} == '0' should equal false?

Mohammad Sami 2020-10-9