How can I define the name of a variable that depends on the "i" of a for cycle

Hello MATLAB community,

I would like to improve my code and create different variables with names that depend on the “I” of a for cycle.

What I have is this:

………………………………………………………………………………………………………………………………………………………………

freq_i=1 %initial frequency

freq_d=1000 %final frequency

SEN=1

FRF_RZ_DAM0_KP2_SEN1(:,1)=E02(freq_i+freq_d*(SEN-1):freq_d*SEN); % Frequency [Hz]

SEN=2

FRF_RZ_DAM0_KP2_SEN2(:,1)=E02(freq_i+freq_d*(SEN-1):freq_d*SEN); % Frequency [Hz]

SEN=3

FRF_RZ_DAM0_KP2_SEN3(:,1)=E02(freq_i+freq_d*(SEN-1):freq_d*SEN); % Frequency [Hz]

………………………………………………………………………………………………

So, I get variables that depend on the number of SEN

For SEN=1 I get FRF_RZ_DAM0_KP2_SEN1(:,1)

For SEN=2 I get FRF_RZ_DAM0_KP2_SEN2(:,1)

For SEN=3 I get FRF_RZ_DAM0_KP2_SEN3(:,1)

For the sake of efficiency I would like to create a for loop that could name these variables automatically. For example

for SEN=1:1=30

FRF_RZ_DAM0_KP2_SEN?(:,1)

end for

I believe this is quite easy and have been over it for a while.

Thanks in advance for your help,

Hugo Policarpo

Invited Professor at Instituto Superior Técnico

University of Lisbon

Portugal

Answer 1

[Ameer Hamza]

"For the sake of efficiency I would like to create a for loop that could name these variables automatically."

This is one of the most inefficient things you can do with your code: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval. Most efficient way is to save values in numeric or cell arrays.

[Hugo Policarpo]

Dear Ameer Hamza,

thanks for you quick and useful reply.

However, what is the other way of doing it?

I think you can define a string and use it to name the variable.

But I am not able to apply it.

Any suggestions?

Thanks in advance

[Ameer Hamza]

The correct way to do this depends on dimensions of FRF_RZ_DAM0_KP2_SEN1, FRF_RZ_DAM0_KP2_SEN2, FRF_RZ_DAM0_KP2_SEN3, ... If all of them has equal number of columns then save them as columns of matrix

for SEN=1:1:30
    FRF_RZ_DAM0_KP2_SEN(:,SEN)
end

If they have different number of elements then use cell array

for SEN=1:1:30
    FRF_RZ_DAM0_KP2_SEN{SEN} = ...
end

[Hugo Policarpo]

Dear Ameer Hamza,

it works perfectly!

I adapted it to something like this:

for SEN=1:1:12
    FRF_RZ_DAM0_KP2_SEN{1,SEN}=E02(freq_i+freq_d*(SEN-1):freq_d*SEN)% Frequency [Hz]
    FRF_RZ_DAM0_KP2_SEN{2,SEN}=E03(freq_i+freq_d*(SEN-1):freq_d*SEN)% Rotation Z 
    FRF_RZ_DAM0_KP2_SEN{3,SEN}=E04(freq_i+freq_d*(SEN-1):freq_d*SEN)% Acelertion Z (derived from the rotations)
end

This way I store my data in an array of 12 lines and 3 columns in which each column corresponds to a different sensor.

If you have any suggestion of improvement it is more than welcome.

Thanks for your help!

King regards,

Hugo Policarpo

[Ameer Hamza]

I think this perfectly summarizes your data. This will be an optimal approach, in my opinion.

[Hugo Policarpo]

Dear Ameer Hamza,

tanhks for your help and support.

Kind regards,

Hugo Policarpo