MATLAB: Struct for loop syntax difficulty

for loopsindexingloopsstructs

Not sure what I'm doing wrong with the following loop:

      for p=66:1:95;
      Site(p).Day = Data((Data(:,4) == p),:)
      end

I want Site(p) to contain all data from only the days (in column 4) that I am looking for, which should give a 1×29 struct, but at the moment Site(p) is a 1×95 struct where the first 65 entries are blank ([]). I assume the problem is in the first line, but when I make p the correct size (eg p=1:29) I get an error message about dimension mismatch. Also, if I set another vector, eg n=95-66 and p=1:n, I get the same error message. I can't see what I'm doing wrong.

Best Answer

Site(p-65).Day = Data((Data(:,4) == p),:)

Related Solutions

MATLAB: How to read only some lines and skip others

>> cssm('cssm.txt')
ans =
         0  -69.1127  -68.9000  -65.2096
    0.0270  -69.1062  -68.8937  -65.2083
    0.0540  -69.0996  -68.8874  -65.2069
    0.0810  -69.0931  -68.8811  -65.2056

where

function  out = cssm( filespec )
    fid = fopen( filespec );
    cac = textscan( fid, '%f%f%f%f%*[^\n]', 4, 'Delimiter',',' ...
                ,   'CollectOutput',true, 'Headerlines',1 );
    [~] = fclose( fid );
    out = cac{:};
end

and cssm.txt contains your data

MATLAB: How to access a structure array using a loop

First, note that with your example, at the end p is a structure with just one field 'p10'. To create the structure you want:

p = struct('p1', {p1}, 'p2', {p2}, 'p3', {p3}, ...)

Also note that you don't need to put the field contents into a cell array, unless this content is itself a cell array. so:

 p = struct('p1', p1, 'p2', p2, ...)

may work just as well.

Secondly, your for loop is not going to work, ['p1' 'p2' 'p3' ...] is exactly the same as 'p1p2p3....', and i will take in turn the values 'p', then '1', then 'p' again, then '2', etc. You need to use a cell array

Finally, to use dynamic field names, you enclose the variable holding the field name in round brackets ().

So:

p = struct('p1',{p1}, 'p2',{p2}, 'p3',{p3}, 'p4',{p4}), 'p5',{p5}, 'p6',{p6}, 'p7',{p7}, 
'p8',{p8}, 'p9',{p9}, 'p10',{p10});
for fn = {'p1', 'p2', 'p3', 'p4', 'p5', 'p6', 'p7', 'p8', 'p9', 'p10'}
%or better: for fn = fieldnames(p)'
   o = p.(fn{1});
end

Best Answer

Related Solutions

MATLAB: How to read only some lines and skip others

MATLAB: How to access a structure array using a loop

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