Searching for a matched string within nested cell and delivering the index

I have a nested cell array which is called values.

In this example, there are 5 sub cells. Usually this number is variable from 1 to 30.

Each cell has two subsub cells:

• the first one, or values{5,1}{1,1}, has always only one char value (in this example, TOTAL or MGS)
• the second one, or values{5,1}{2,1}, has matrix consisting from tow columns: on the left - tempearature values, on the right - physical properties.

My goal is twofold:

1. to find the sub cell containing the char value 'TOTAL' (values{5,1}) and somehow to get the index of the matrix (the output would be values{5,1}{2,1}).
2. to get from the matrix the physical property at 298,15. If the value for room temperature is missing, take the closest value to the RT (the output would be 7 or 6 (if the value at room temperature is missing))

To adress the 1st problem, I have written my handmade solution. This code works if there is in the char TOTAL in a{5,1}{1,1}. However, this string could be elsewhere. In this case, I have a problem.

To find a solution for the 2nd question, I created following script, which from my point of view could be simplier to read.

    for m = 1:numel(values)
        for n = 1:numel(values(m))
            a = values(m);
            if string(a{5,1}{1,1}) == 'TOTAL'
                k = a{5,1}{2,1}(:,1); %column with temp numbers
                n = 298.15;           %RT
                [~,~,idx] = unique(round(abs(k-n)));
                minVal = k(idx==1);
                valueAtRT = sprintf('%f', a{1,1}{5,1}(length(a{1,1}{5,1})+idx));
                break;
            end
        end
    end

How can I do this?

Thanks for any help.

[Stephen23]

@Nazar Adamchuk: please upload sample data in a mat file by clicking the paperclip button.

[Nazar Adamchuk]

Stephen Cobeldick done

Answer 1

[per isakson]

Assume there is ONE cell contaning 'TOTAL'

Try

%%
ix = find( cellfun( @(cac) strcmp(cac{1},'TOTAL'), values ) );
num = values{ix}{2};
fys = interp1( num(:,1), num(:,2), 298.15 );

The value of fys is

>> fys
fys =
       7.0931       

Better

%%
is = cellfun( @(cac) strcmp(cac{1},'TOTAL'), values );
num = values{is}{2};
fys = interp1( num(:,1), num(:,2), 298.15 );

[Nazar Adamchuk]

To find the closest value to 298.15 (if for example, the value at 298.15 K is missing and next value would be at 303.15 K):

instead of

fys = interp1( num(:,1), num(:,2), 298.15 );

I would use:

[ ~, ix ] = min( abs(num(:,1)-298.15 ) );
fys = num(ix,2);

And the correct output would be:

7.091815981

Is it correct @per isakson?

[per isakson]

Yes, but isn't

fys = interp1( num(:,1), num(:,2), 298.15, 'nearast', 'extrap' );

more readable?

[Nazar Adamchuk]

I replaced my code with you update. I receive through this error message (num variable you can see in attachment):

Error using interp1>sanitycheckmethod (line 285)
Invalid interpolation method.

Error in interp1>parseinputs (line 382)
        method = sanitycheckmethod(penultimate);

Error in interp1 (line 112)
        parseinputs(X,V,penultimate,last,nargin,ndataarg,pp);

Error in searchPropertyValue (line 18)
    fys = interp1( num(:,1), num(:,2), 298.15, 'nearast', 'extrap' );

[per isakson]

My interp1-statement runs without problem on R2018b.

>> load('num.mat')
>> fys = interp1( num(:,1), num(:,2), 298.15, 'nearast', 'extrap' );
>> fys
fys =
       7.0931       

Your error message isn't compatible with the source code of interp1 of R2018b. The function is refactored in a later release and the error checking is stricter.

I misspelled 'nearast'. Thus, Invalid interpolation method I assume. Should be 'nearest'

[Nazar Adamchuk]

Hello, there is some problem with the function while processing the values variable (I have attached it as values.mat).

I receive the error:

Non-scalar in Uniform output, at index 1, output 1. Set 'UniformOutput' to false.

Then I follow the advise from Matlab and add the 'UniformOutput, false and your solution looks like that:

is = cellfun( @(cac) strcmp(cac{1},'TOTAL'), 'uniformoutput',false );

Unfortunately, after rerunning the code to process values variable (I have attached it as values1.mat) which has different content from values.mat:

Error using cellfun
Input #2 expected to be a cell array, was char instead.

Can you help be find the solution which will pocess values.mat and values1.mat? Thanks!

[Nazar Adamchuk]

I call back my previous comment! Everything fine after I added 'uniformoutput',false