structcut

 structure=structcut(structure,i)

 I find I often want to shrink a structure
 of the form

   s.a(n)
   s.b(n)
   s.c(n)
 
 according to some matrix of indices i.
 For example it's a pain to do:

   x=s.a>1;
   s.a=s.a(x);
   s.b=s.b(x);
   s.c=s.c(x);

 and if I add another field I have to change
 the code in multiple places.

 This function automatically cuts all fields
 so the code becomes:

   x=s.a>1;
   s=structcut(s,x);

 and continues to work if fields are added.

 Now extended so that fields can be 2D - will try to figure
 out which dimension to cut over by looking for the dim which is
 equal length for all fields. If all are same cut will occur over
 rows.

0001 function s=structcut(s,x)
0002 % structure=structcut(structure,i)
0003 %
0004 % I find I often want to shrink a structure
0005 % of the form
0006 %
0007 %   s.a(n)
0008 %   s.b(n)
0009 %   s.c(n)
0010 %
0011 % according to some matrix of indices i.
0012 % For example it's a pain to do:
0013 %
0014 %   x=s.a>1;
0015 %   s.a=s.a(x);
0016 %   s.b=s.b(x);
0017 %   s.c=s.c(x);
0018 %
0019 % and if I add another field I have to change
0020 % the code in multiple places.
0021 %
0022 % This function automatically cuts all fields
0023 % so the code becomes:
0024 %
0025 %   x=s.a>1;
0026 %   s=structcut(s,x);
0027 %
0028 % and continues to work if fields are added.
0029 %
0030 % Now extended so that fields can be 2D - will try to figure
0031 % out which dimension to cut over by looking for the dim which is
0032 % equal length for all fields. If all are same cut will occur over
0033 % rows.
0034 
0035 % first let's check if it even needs to be cut.
0036 if(length(x)==1)
0037   if(x==0)
0038     s = [];
0039   else
0040     s = s;
0041   end
0042   return;
0043 end
0044 
0045 names=fieldnames(s);
0046 
0047 % Get sizes of fields
0048 for i=1:length(names)
0049   d(i,:)=size(getfield(s,char(names(i))));
0050 end
0051 
0052 if(all(d(:,1)==d(1,1)) & d(1,1)~=1)
0053   for i=1:length(names)
0054     d=getfield(s,char(names(i)));
0055     d=d(x,:);
0056     s=setfield(s,char(names(i)),d);
0057   end
0058 else
0059   if(all(d(:,2)==d(1,2)) & d(1,2)~=1)
0060     for i=1:length(names)
0061       d=getfield(s,char(names(i)));
0062       d=d(:,x);
0063       s=setfield(s,char(names(i)),d);
0064     end
0065   else
0066     error('Dont know which array dim to cut over');
0067   end
0068 end