creating variables from structures in matlab

Question

I have the following example which expresses the type of problem that I'm trying to solve:

clear all
textdata = {'DateTime','St','uSt','Ln','W'};
data = rand(365,4);
Final = struct('data',data,'textdata',{textdata})
clear textdata data

From this, Final.data contains values which correspond to the headings in Final.textdata excluding the first ('DateTime') thus Final.data(:,1) corresponds to the heading 'St'... and so on. What I'm trying to do is to create a variable in the workspace for each of these vectors. So, I would have a variable for St, uSt, Ln, and W in the workspace with the corresponding values given in Final.data.

How could this be done?

macduff · Accepted Answer · 2012-02-20 15:05:34Z

3

Will this solve your problem:

    for ii=2:length( textdata )
      assignin('base',Final.textdata{ii},Final.data(:,ii-1));
    end

Let me know if I misunderstood.

edited Feb 20, 2012 at 15:05

answered Feb 20, 2012 at 14:32

macduff

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Emma Over a year ago

It is kind of what I was looking for, but the data that I have is stored in a structure, similar to 'Final' above (question amended).

Pursuit · Accepted Answer · 2012-02-20 15:08:19Z

2

The direct answer to your question is to use the assignin function, like so (edit: just like macduff suggested 10 minutes ago):

%Starting with a Final structure containing the data, like this
Final.textdata = {'DateTime','St','uSt','Ln','W'};
Final.data = rand(365,4);

for ix = 1:4
    assignin('base',Final.textdata{ix+1}, Final.data(:,ix));
end

However, I strongly discourage using dynamic variable names to encode data like this. Code that starts this way usually ends up as spaghetti code full of long string concatenations and eval statements. Better is to use a structure, like this

for ix = 1:4
    dataValues(Final.textdata{ix+1}) = Final.data(:,ix);
end

Or, to get the same result in a single line:

dataValues = cell2struct(num2cell(Final.data,1), Final.textdata(2:end),2)

edited Feb 20, 2012 at 15:08

answered Feb 20, 2012 at 14:43

Pursuit

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1 Comment

Emma Over a year ago

great method, but as stated above the data is originally in a structure so how would I apply this to my data (see amended question), i.e. how do I get to the different cells in textdata?

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