How can I extract data from a table and put it into a new one?

Question

Tessa Coenraad 2019-5-22

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回答： Peter Perkins 2019-5-22

Hi!

We made a loop to create a table where all our measurements can be put in. The problem is, that all the measurements are done 4 times(for 1 machine), and we want a new table with the four measurements (from one machine) put in seperate colums.

Our loop looks like this:

files=dir('*.log');

M=NaN(length(files),1);

Lek=M;

B=M;

C=M;

R=M;

PS=M;

TV=M;

For i=1:length(files)

out=textscan(files(i).name,'M%f_Lek%f_B%f_C%f_R%f_PS%f');

A = readcell(files(i).name); %data inladen

Z = string(A);

time = Z(7:end,1); %van time een vector maken

time = strrep(time, ',', '.'); %komma's in vector in punten veranderen

time = str2double(time);

flow = Z(7:end,2);

flow= strrep(flow, ',', '.');

flow = str2double(flow);

flow = flow./60;

flowpos = flow;

flow(flow<0)= 0;

RR=23;

volpos = trapz(time, flow);

TV(i)= (volpos./RR);

TV(i)= TV(i).*1000;

M(i)=out{1};

Lek(i)=out{2};

B(i)=out{3};

C(i)=out{4};

R(i)=out{5};

PS(i)=out{6};

end

T=table(M,Lek,B,C,R,PS,TV,'VariableNames',{'M','Lek','B','C','R','PS','TV'})

If M is 1, we want TV to be in column '1' of the new table, if M is 2, we want TV to be in column '2' of the new table, etc....

How can we do this?

We managed to create a new table just like above, but he wont fill in the TV's.

Thanks in advance, Tessa

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Answer 1

Luuk van Oosten 2019-5-22

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Beste Tessa,

You almost wrote it yourself already, if I understand your problem correctly....? You already wrote in pseudocode a perfect example of an elseif statement when you said:

"If M is 1, we want TV to be in column '1' of the new table, if M is 2, we want TV to be in column '2' of the new table, etc...."

% so you have some kind of M, lets say M is 2
M = 2
if M==1
yourcodeforputtingitincolumn1ofthetable
elseif M ==2
    yourcodeforputtingitincolumn2ofthetable
elseif M ==3
    yourcodeforputtingitincolumn3ofthetable
elseif M == N
    yourcodeforputtingitincolumnNofthetable
else
    disp('back to the drawing board')
end

If this is not what you meant, please clarify.

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Tessa Coenraad 2019-5-22

The problem is that we dont know how to write the code for putting it into the right column of a new table. Also i'm not sure if MATLAB "knows" it has to read out of the first table T....

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Answer 2

Peter Perkins 2019-5-22

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With no example, it's hard to understand what you have and what you want to end up with, but your description sounds very much like you want to use unstack.