MATLAB Answers

How do I create variable names from string variables

148 views (last 30 days)
selena
selena on 12 Aug 2013
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

  0 Comments

Sign in to comment.

Accepted Answer

Matt Kindig
Matt Kindig on 12 Aug 2013
Edited: Matt Kindig on 12 Aug 2013
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

  2 Comments

selena
selena on 12 Aug 2013
Thanks, how would I assign a date stamp to the variables?
Matt Kindig
Matt Kindig on 12 Aug 2013
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.

Sign in to comment.

More Answers (1)

Andrei Bobrov
Andrei Bobrov on 13 Aug 2013
Edited: Andrei Bobrov on 13 Aug 2013
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);

  1 Comment

Matt Kindig
Matt Kindig on 15 Aug 2013
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.

Sign in to comment.

Sign in to answer this question.