How to call a specific element of a table

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Zeynab Mousavikhamene
编辑： Andrei Bobrov 2019-8-30
I want to
find the "radius" in which "time" is 2 and p"erhexagon" is 2.1667. There might be more than one radius that matches this criteria.
Any suggestion?
  2 个评论
KALYAN ACHARJYA
KALYAN ACHARJYA 2019-8-29
编辑：KALYAN ACHARJYA 2019-8-29
Have you check here?
Still unable to resolve it, please attach the table.
madhan ravi
madhan ravi 2019-8-29
Learn to attach data as .mat file as shown by Andrei below, attaching a screenshot is useless!

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采纳的回答

Adam Danz
Adam Danz 2019-8-29
编辑：Adam Danz 2019-8-29
Assuming your table is named "T",
% 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;
  2 个评论
Zeynab Mousavikhamene
Zeynab Mousavikhamene 2019-8-29
编辑：Zeynab Mousavikhamene 2019-8-29
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
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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更多回答（1 个）

Andrei Bobrov
Andrei Bobrov 2019-8-29
编辑：Andrei Bobrov 2019-8-29
load data.mat
lo = ismembertol(T{:,{'time','perhexagon'}},[2,2.1667],'ByRows',true,...
'DataScale',[1 .00001]);
out_radius = T.radius(lo);
  2 个评论
Zeynab Mousavikhamene
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
Andrei Bobrov 2019-8-30
编辑：Andrei Bobrov 2019-8-30
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
>>

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