Avoid restarting for-loop - matlab

Question

I have a folder with pictures. For each picture, I want to take the maximum value and add it to a new matrix (I created a zeros-matrix, so the zeroes will be replaced with the new values).
This is my code:
function handles = original(hObject, eventdata, handles)
handles.weed=handles.selected;
pic=imread(handles.me);
handles.pic=pic;
axes(handles.axes1)
imshow(pic);
num=max(pic(:))
zeroMat = zeros(1,70);
handles.zeroMat = zeroMat;
for i =1:3
if zeroMat(1,i)~= 0;
i=i+1
else
zeroMat(1,i)=num
break
end
end
zeroMat(1,i)=num
Every time I select a new picture, the zeromat restarts itself to a new zeros-matrix. I know why it happens, but unfortunately I don't know how to overcome it.
This is the output:
pic1:
zeroMat =
Columns 1 through 20
255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Columns 21 through 40
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Columns 41 through 60
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Columns 61 through 70
0 0 0 0 0 0 0 0 0 0
pic2:
Columns 1 through 20
203 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Columns 21 through 40
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Columns 41 through 60
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Columns 61 through 70
0 0 0 0 0 0 0 0 0 0

Answer 1

I can't tell how this function is being invoked, so can't advice how to change up the logic. A rough fix could be to include the line
if ~isfield(handles,'zeroMat')
handles.zeroMat = zeros(1,70);
end % if
which should create handles.zeroMat the first time the function is run. You could then do something like
firstNonzero = find(handles.zeroMat > 0, 1, 'first'); % 'first' not needed, default
handles.zeroMat(firstNonzero) = max(pic(:));