How to call a specific element of a table

% find the rows where time equals 2 and perhexagon equals exactly 2.1667
rowidx = T.time == 2 & T.perhexagon == 2.1667; 
% use the row index to get the chosen radii
chosenRads = T.radius(rowidx); 

Note that if you have trouble matching the floating point decimals, you may have to build in a tolerance instead of requiring an exact match. Example below.

% Define tolerance
tol = 0.001; %accepted if perhexagon value is +/-tol from target
% find the rows where time equals 2 and perhexagon equals exactly 2.1667
rowidx = T.time == 2 & abs(T.perhexagon - 2.1667)<tol; 

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Zeynab Mousavikhamene 2019-8-29

编辑：Zeynab Mousavikhamene 2019-8-29

在 MATLAB Online 中打开

Thanks.

I tried:

% find the rows where time equals 2 and perhexagon equals exactly 2.1667
rowidx = Acc_cellcount.time == 2 & Acc_cellcount.perhexagon == 2.1667; 
% use the row index to get the chosen radii
chosenRads = Acc_cellcount.radius(rowidx);

and it came out:

chosenRads =
  0×1 empty double column vector

Adam Danz 2019-8-29

This is where my "note" comes in at the end of my answer. Your "perhexagon" values aren't really 2.1667. Those are just the first 4 decimal places. So you need to build in a tolerance. For example, accept any rows where perhexagon is within 0.0001 within the target value. I'll update my answer.

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Answer 2

Andrei Bobrov 2019-8-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/478141-how-to-call-a-specific-element-of-a-table#answer_389677

编辑：Andrei Bobrov 2019-8-29

在 MATLAB Online 中打开

data.mat

load data.mat
lo = ismembertol(T{:,{'time','perhexagon'}},[2,2.1667],'ByRows',true,...
                                                 'DataScale',[1 .00001]);
out_radius = T.radius(lo);

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Zeynab Mousavikhamene 2019-8-29

编辑：Zeynab Mousavikhamene 2019-8-29

Got this error:

Error using load

Unable to read file 'data.mat'. No such file or directory.

I run for the second time without "Error using load" and I got :

"out_radius =

0×1 empty double column vector"

Tried multiple 'DataScales': [1 .001] or [1 .1] or [1]

all gave empty out_radius.

Andrei Bobrov 2019-8-30

编辑：Andrei Bobrov 2019-8-30

在 MATLAB Online 中打开

You do not know how to download, sorry.

Exsample my laptop with Ubuntu (I from Russia :) ):

>> load '/home/andrei/Загрузки/data.mat'
>> lo = ismembertol(T{:,{'time','perhexagon'}},...
   [2,2.1667],'ByRows',true,'DataScale',[1 .00001]);
out_radius = T.radius(lo)
out_radius =
     1
     2
>>  