converting cell of strings in arry or cell of numbers

Question

Syed Zohaib Ali 2011-12-28

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https://ww2.mathworks.cn/matlabcentral/answers/24865-converting-cell-of-strings-in-arry-or-cell-of-numbers

评论： Oli Fairfax 2021-4-1

I have a cell of strings 'tsince' having dimension 143 by 1 as '4632' '0.00000000' '-1440.00000000' '-1438.00000000' '-1436.00000000' '-1434.00000000' '-1432.00000000' '-1430.00000000' '-1428.00000000' . . . . '1436.00000000' '1438.00000000' '1440.00000000'

 I want to convert it to an array or cell of numbers. I tried with str2num() but it gives the following error:

>> tsince2=str2num(tsince) ??? Error using ==> str2num at 33 Requires string or character array input.

I am new to matlab. somebody can please help out how to do this. Thanks in advance

Zohaib

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Answer 1

Jan 2011-12-28

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A surprisingly efficient method even for very large input:

C = {'4632', '0.00000000', '-1440.00000000', '-1438.00000000', ...
     '-1436.00000000', '-1434.00000000', '-1432.00000000' '-1430.00000000', ...
     '-1428.00000000', '1436.00000000', '1438.00000000', '1440.00000000'};
S = sprintf('%s ', C{:});
D = sscanf(S, '%f');

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Josh Philipson 2021-3-30

clever. Thanks Jan!

Oli Fairfax 2021-4-1

在 MATLAB Online 中打开

I had to make my cell array a single column then ensure empties were converted to NaN (otherwise they got lost) but this worked MUCH quicker than str2double for my example, thanks Jan!

C2 = reshape(C,[],1);
C2(cellfun(@isempty,C2)) = {'NaN'};
S = sprintf('%s ', C2{:});
D = sscanf(S, '%f');
Data = reshape(D, [], size(C,2));

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Answer 2

Nirmal Gunaseelan 2011-12-28

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STR2NUM requires a single string to work on. You need to loop around the individual cell elements and use STR2NUM. CELLFUN is a better way of doing the same - check out the doc.