Subscript indices must either be real positive integers or logicals.while using indexing

Question

want2know 2014-2-17

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https://ww2.mathworks.cn/matlabcentral/answers/116442-subscript-indices-must-either-be-real-positive-integers-or-logicals-while-using-indexing

评论： want2know 2014-2-17

采纳的回答： Mischa Kim

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Hi all,

After performing some processing, now the variable 'a' contains [2 5 9].

Let say i have another variable 'b', variable 'b' is pre-initialized to be zero depending on a length of input, let say 10. b = [0 0 0 0 0 0 0 0 0 0];

What I want is, the elements that are stated in variable 'a' should be set ONE in variable 'b'. b= [0 1 0 0 1 0 0 0 1 0]

I did make sure variable 'a' contains only positive integers.

have added this line "a=round(a); b(a)=1;"

'a' can only be positive integers, I confirm and have checked.

I still I got the same error... Appreciate any idea, thanks

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Answer 1

Mischa Kim 2014-2-17

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https://ww2.mathworks.cn/matlabcentral/answers/116442-subscript-indices-must-either-be-real-positive-integers-or-logicals-while-using-indexing#answer_124641

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Use clear all and then copy-paste-execute

 a = [2 5 9];
 b = [0 0 0 0 0 0 0 0 0 0];
 b(a) = 1

Does that do the trick?

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want2know 2014-2-17

I tried by replacing this line a = zeros(1,10); with a =[];

still running to see if it works

want2know 2014-2-17

Thanks a lot, Mischa Kim

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Answer 2

Jos (10584) 2014-2-17

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https://ww2.mathworks.cn/matlabcentral/answers/116442-subscript-indices-must-either-be-real-positive-integers-or-logicals-while-using-indexing#answer_124640

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Are you sure they are positive and larger than zero ? … I am pretty sure they are not!

remove the semi-colon to see

a = round(a)
b(a) = 1

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want2know 2014-2-17

Thanks, sorry for my careless mistake, please forgive, there are zero which i overlooked.

As mentioned in the post, initially b = [0 0 0 0 0 0 0 0 0 0]; and variable 'a' is [2 5 9 0 0 0 0 0 0 0] after b(a)=1; variable 'b is now b= [0 1 0 0 1 0 0 0 1 0].

variable 'a' needs to be initialized with zeros at the beginning of m file, how could I avoid this? so that 'a' is [2 5 9] instead of [2 5 9 0 0 0 0 0 0 0]?

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