Compress variable assignment into for loop in matlab [duplicate] - matlab

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I want to compress part of my code into a for loop. The code looks like this:
dataMixSp1 = [dataSp1{1}; dataSp1{2}; dataSp1{3}; dataSp1{4};];
dataMixSp2 = [dataSp2{1}; dataSp2{2}; dataSp2{3}; dataSp2{4};];
dataMixSp3 = [dataSp3{1}; dataSp3{2}; dataSp3{3}; dataSp3{4};];
dataMixSp4 = [dataSp4{1}; dataSp4{2}; dataSp4{3}; dataSp4{4};];
dataMixSp5 = [dataSp5{1}; dataSp5{2}; dataSp5{3}; dataSp5{4};];
dataMixSp6 = [dataSp6{1}; dataSp6{2}; dataSp6{3}; dataSp6{4};];
dataMixSp7 = [dataSp7{1}; dataSp7{2}; dataSp7{3}; dataSp7{4};];
dataMixSp8 = [dataSp8{1}; dataSp8{2}; dataSp8{3}; dataSp8{4};];
dataMixSp9 = [dataSp9{1}; dataSp9{2}; dataSp9{3}; dataSp9{4};];
dataMixSp10 = [dataSp10{1}; dataSp10{2}; dataSp10{3}; dataSp10{4};];
The problem is that I don't know how to dynamically create variables inside the for loop.
I tried this but it is not working:
a = 'dataMixSp';
for idx = 1:10
[a num2str(idx)] = [['dataSp', num2str(idx), '{1}']; ['dataSp' num2str(idx) '{2}']; ['dataSp' num2str(idx) '{3}']; ['dataSp' num2str(idx) '{4}']; ];
end

Answer 1

To have Matlab evaluate an instruction in a string, use the eval function. For the problem you show, this could be done as:
root = 'dataMix';
part = 'dataSp';
for k=1:10
target = sprintf('%s%d', root,k); % creates strings 'dataMix1', 'dataMix2', ...
thisPart = sprintf('%s%d', part,k); %creates strings 'dataSp1, 'dataSp2', ...
rhs = '['; % the opening of the right-hand-side of the assignment
for n=1:4
rhs=sprintf('%s%s{%d};',rhs,thisPart,n);%appends 'dataSp1{1}, dataSp1{2}...
end
rhs=strcat(rhs(1:end-1),']');% close the right-hand-side
% note the (1:end-1) to remove the ';' between the last variable and the ']'
instruction = sprintf('%s = %s;',target,rhs); % create a Matlab instuction
eval(instruction) % have Matlab evaluate the instruction
end
Although, as #tryman said, sometimes the problem is easier to solve saving the data in a different way.
Hope this helps
JAC

Answer 2

for idx = 1:10
eval( [ 'dataMixSp' num2str(idx) '= [ dataSp' num2str(idx), '{1}; dataSp' num2str(idx) '{2}; dataSp' num2str(idx) '{3}; dataSp' num2str(idx) '{4} ];' ] )
end
Will execute the following code:
dataMixSp1= [ dataSp1{1}; dataSp1{2}; dataSp1{3}; dataSp1{4} ];
dataMixSp2= [ dataSp2{1}; dataSp2{2}; dataSp2{3}; dataSp2{4} ];
dataMixSp3= [ dataSp3{1}; dataSp3{2}; dataSp3{3}; dataSp3{4} ];
dataMixSp4= [ dataSp4{1}; dataSp4{2}; dataSp4{3}; dataSp4{4} ];
dataMixSp5= [ dataSp5{1}; dataSp5{2}; dataSp5{3}; dataSp5{4} ];
dataMixSp6= [ dataSp6{1}; dataSp6{2}; dataSp6{3}; dataSp6{4} ];
dataMixSp7= [ dataSp7{1}; dataSp7{2}; dataSp7{3}; dataSp7{4} ];
dataMixSp8= [ dataSp8{1}; dataSp8{2}; dataSp8{3}; dataSp8{4} ];
dataMixSp9= [ dataSp9{1}; dataSp9{2}; dataSp9{3}; dataSp9{4} ];
dataMixSp10= [ dataSp10{1}; dataSp10{2}; dataSp10{3}; dataSp10{4} ];
Arno