How do I create variable names from string variables

If I have 2 variables, ID has a column of strings like 'height' or 'speed', data has a column of corresponding variables.

ie

ID = 'height' 'height' 'height' 'speed' 'speed'

data = 10;10;7;2.4;2.1

How do I create the variable 'height' and a variable speed with the corresponding data.

ie

height = 10;10;7

speed = 2.4;2.1

Answer 1

[Matt Kindig]

If you can, avoid doing this. This explains why: http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

Instead, make them fields of a structure. You can do something like this:

vars = struct();  %structure to hold your variables
ID = {'height' 'height' 'height' 'speed' 'speed'};
data = [10;10;7;2.4;2.1]; 
fields = unique(ID);   %get variable names as field names
for k=1:length(fields),  %for each unique variable
   fld= fields{k};         %field name
   tf = ismember(ID, fld);   %which corresponding data
   vars.(fld) = data(tf);  %assign to field
end
vars.height;  %height variables
vars.speed;   %speed variables

[selena]

Thanks, how would I assign a date stamp to the variables?

[Matt Kindig]

How do you mean? Do you have an additional field in 'ID' that is called 'date' or similar? I wrote this code to be extensible to an arbitrary set of fields, so I think that additional ID elements (with corresponding values in 'data') should work fine.

Answer 2

[Andrei Bobrov]

ID = {'height' 'height' 'height' 'speed' 'speed'};
data = [10;10;7;2.4;2.1];

[i0,i1,i1] = unique(ID);
vars = cell2struct(accumarray(i1(:),data(:),[],@(x){x}),i0,1);

[Matt Kindig]

I should have figured there was an easy way to do this using accumarray. Try as I might, I still can't get the hang of that function.