Can I use for loop to do the same process to four tables?

Question

Lorna Belford 2019-6-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/469340-can-i-use-for-loop-to-do-the-same-process-to-four-tables

评论： Lorna Belford 2019-6-28

Hiya, Im trying to execute this for loop, but as well as changing the index, I also want to chnage the table that the original for loop is acting on.

I have four tables each with a different club name-

FMData_Test_BBSH_reordered

FMData_Test_NewCal_reordered

FMData_Test_3Wood_reordered

FMData_Test_Wooden_reordered

My original loop below works,

  for i=1:13   
%Use rotation matrix to rotate the offline (x) and Carry distance (y)
BBSH_x(i)=(FMData_Test_BBSH_reordered{i,3}.*cos(Theta_carry(1,1)))-(FMData_Test_BBSH_reordered{i,4}*sin(Theta_carry(1,1)));
BBSH_y(i)=(FMData_Test_BBSH_reordered{i,3}.*sin(Theta_carry(1,1)))+(FMData_Test_BBSH_reordered{i,4}*cos(Theta_carry(1,1)));
end

but rather than write this code out four times, each time changing the club name e.g.BBSH to the next club I was wondeirng if i could create another for loop to do this.

I have tried :

Club_names={'BBSH','New Cal','Ping 3 Wood','Wooden'}; 
for ii=Club_names 
    for i=1:13   
%Use rotation matrix to rotate the offline (x) and Carry distance (y)
ii_x(i)=(FMData_Test_ii_reordered{i,3}.*cos(Theta_carry(1,1)))-(FMData_Test_ii_reordered{i,4}*sin(Theta_carry(1,1)));
ii_y(i)=(FMData_Test_ii_reordered{i,3}.*sin(Theta_carry(1,1)))+(FMData_Test_ii_reordered{i,4}*cos(Theta_carry(1,1)));
end
    end 

but this doesnt work as Matlab says the varibale FMData_Test_ii_reordered is not defined.

Any suggestions greatly appreciated.

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Stephen23 2019-6-28

编辑：Stephen23 2019-6-28

"Any suggestions greatly appreciated. "

Do NOT put meta-data (e.g indices, club names, etc.) into variable names.

Why not?

Because then what happens is that you will try to access those names dynamically... and dynamically accessing variable names is one way that beginners force themselves into writing slow, complex, buggy code that is hard to debug. Read this to know why:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Meta-data is data, and data should be stored in a variable, not in a variable's name.

Your task would be trivial if you had stored this data in one array (e.g. a cell array, a table, etc.) and then just used simple, efficient indexing.

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Answer 1

Bob Thompson 2019-6-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/469340-can-i-use-for-loop-to-do-the-same-process-to-four-tables#answer_381185

To the best of my knowledge it is not possible to dynamically loop through variables. I would suggest combining the tables into one variable, perhaps a structure, and then looping through the index of that new variable.

structure = struct('table',{FMData_Test_BBSH_reordered, FMData_Test_NewCal_reordered, FMData_Test_3Wood_reordered, FMData_Test_Wooden_reordered});
for i = 1:length(structure)
    % Do you stuff here. Call each table with structure(i).table
end