Running code via function

Hi,

I am using code to make a movie from string files (text files) via function and got and error message below;

Error using fscanf
Invalid file identifier. Use fopen to generate a valid file identifier.

Error in LISFLOOD_mov_v2>read_file (line 73)
A = fscanf(fin,'%s',1); ncols = fscanf(fin,'%f',1);           %#ok<NASGU>

Error in LISFLOOD_mov_v2 (line 49)
    [DEPTH, ncols, nrows, xllcorner, yllcorner, cellsize] = read_file (resfile)

I follow an example how to use function code because I took the code from this source; https://source.ggy.bris.ac.uk/wiki/LISFLOOD-FP_and_MATLAB. The function code is as followings;

function LISFLOOD_mov (resroot,fileex,vartype,num_snaps,snapint,dem,demCS,depthCS,framesPS,movQ) 

% LISFLOOD_mov generates movies of LISFLOOD-FP output
%
% LISFLOOD_mov (resroot,fileex,vartype,num_snaps,snapint,dem,demCS,depthCS,framesPS,movQ)
% 
% where 
% resroot is the LISFLOOD resroot (relative to m file or absolute)(string)
% fileex is the file extension '.wd' (can be chaned to plot WSE and flows)
% vartype is the name of the variable being plotted e.g. 'Depth'
% num_snaps is the number of snapshot times
% snapint is the time interval between each LISFLOOD-FP snapshot (seconds)
% dem is the name of the demfile (relative or absolute)
% demCS is the range of dem hights to be plotted e.g. demCS = [0,20];
% depthCS is the range of depth values to be plotted e.g. depthCS = [0,10];
% framesPS number of frames per second (each plot is a simgle frame)
% movQ is the movie quality between 1 and 100 (100 is best)
% 
% 8/11/2007. J Neal.
%
% EXAMPLE:
% LISFLOOD_mov ('C:\Experiment1\res22','.wd','Water depth',24,10000,...
% 'C:\Experiment1\dem10m.dem.ascii',[0,60], [0,10],1,100);
%%Movie maker
% read dem filenam is filename and 1 specifies the 0.00 should not be NaN's
[DEM, ncols, nrows, xllcorner, yllcorner, cellsize] = read_file (dem); %#ok<NASGU>
% generate empty .avi file
% A = [resroot,'.avi'];
% mov = avifile(A);
% loop through snapshots
for i = 1:num_snaps
    if i < 10
        resfile = [resroot,'-000',num2str(i),fileex];
    elseif i < 100
        resfile = [resroot,'-00',num2str(i),fileex];
    elseif i < 1000
        resfile = [resroot,'-0',num2str(i),fileex];
    else
        resfile = [resroot,'-',num2str(i),fileex];
    end
    % read in deoth file for resfile i (2 specifies the 0.00 should be NaN
    [DEPTH, ncols, nrows, xllcorner, yllcorner, cellsize] = read_file (resfile);
    % plot data as figure 1
    plotter (DEPTH, DEM, nrows, ncols, cellsize, xllcorner, yllcorner,demCS,depthCS,snapint,i,vartype);
    % get movie frame
    M(i) = getframe(gcf); %#ok<AGROW>
    hold off;
%     mov = addframe(mov,M(i));
    % close the figure
    close all
end 
% % close .avi file
% mov = close(mov);
% generate empty .avi file
disp('Generating .avi movie file');
A = [resroot,fileex,'.avi'];
movie2avi(M,A,'fps',framesPS,'quality',movQ);
disp(A);
%%Read LISFLOOD ascii files using filename
function [OUT, ncols, nrows, xllcorner, yllcorner, cellsize] = read_file (filename)
% read an ascii file
fin = fopen(filename,'r');
A = fscanf(fin,'%s',1); ncols = fscanf(fin,'%f',1);           %#ok<NASGU>
A = fscanf(fin,'%s',1); nrows = fscanf(fin,'%f',1);           %#ok<NASGU>
A = fscanf(fin,'%s',1); xllcorner = fscanf(fin,'%f',1);       %#ok<NASGU>
A = fscanf(fin,'%s',1); yllcorner = fscanf(fin,'%f',1);       %#ok<NASGU>
A = fscanf(fin,'%s',1); cellsize = fscanf(fin,'%f',1);        %#ok<NASGU>
A = fscanf(fin,'%s',1); nodata = fscanf(fin,'%f',1);          %#ok<NASGU>
OUT = fscanf(fin,'%f',[ncols, nrows]);
OUT = OUT';
fclose('all');
% convert nodata to NaN;
for ii = 1:nrows
    for jj = 1:ncols
        if OUT(ii,jj) == nodata
            OUT(ii,jj) = NaN;
        elseif OUT(ii,jj) == -99.000
            % lisflood uses -99.000 as nodat so will also remove these
            OUT(ii,jj) = NaN;
        else
            % do nothing
        end
    end
end
%%Plotter data for movie slide
function plotter (DEPTH, DEM, nrows, ncols, cellsize, xllcorner, yllcorner,demCS,depthCS,snapint,i,vartype)
% number of colors in colormap
num_colors = 64;
% DEM and variable color map
cmap = [gray(num_colors); jet(num_colors)];
% scale DEM and DEPTH data to fit with new colormap
demCS2 = demCS(2)-demCS(1);
dem_scalar = num_colors/demCS2;
DEM2 = DEM*dem_scalar;
depthCS2 = depthCS(2)-depthCS(1);
depth_scalar = num_colors/depthCS2;
DEPTH2 = (DEPTH*depth_scalar)+num_colors+1;
%Plot the DEM
figure1 = figure('PaperSize',[20.98 29.68],'Color',[1 1 1]);
colormap(cmap);
axes1 = axes('Parent',figure1,'YTickLabel',{yllcorner+(nrows*cellsize),yllcorner+cellsize},...
    'YTick', [1,nrows],...
    'YDir','reverse',...
    'XTickLabel',{xllcorner,xllcorner+(ncols*cellsize)-cellsize},...
    'XTick',[1,ncols],...
    'Layer','top');
box('on');
hold('all');
image(DEM2,'Parent',axes1);
axis('equal');axis('tight');
% Overlay the water depth (or other variable)
H = image(DEPTH2);
% code to make depth plot layer transparent
OP = ones(nrows,ncols);
for ii = 1:nrows
    for jj = 1:ncols
        if DEPTH(ii,jj) > 0
        else
            OP(ii,jj) = 0;
        end
    end
end
% make transparent. depth layer must be H
set(H,'AlphaData',OP);
% label colourbar
color_breaks = 5;
colorbreak = num_colors/color_breaks;
SCALE = zeros(color_breaks*2,1);
SCALE(1) = 0.0001;
for j = 1:color_breaks*2
    SCALE(j+1) = colorbreak*j;
end
SCALE(color_breaks+1) = num_colors+1;
VIS_SCALE = zeros(color_breaks*2,1);
VIS_SCALE(1) = demCS(1);
for j = 1:color_breaks-1
    VIS_SCALE(j+1) = ((demCS2/color_breaks)*j)+demCS(1);
end
VIS_SCALE(color_breaks+1) = depthCS(1);
for j = 1:color_breaks
    VIS_SCALE(j+1+color_breaks) = ((depthCS2/color_breaks)*j)+depthCS(1);
end
colorbar('YTick',SCALE,'YTickLabel',VIS_SCALE);
% Label axis
xlabel('BNG easting (m)');
ylabel('BNG northing (m)');
A = [vartype,' over DEM at time ',num2str((i*snapint)),'s'];
title(A);

I try it with typing above function and it seems like the code can run and produce some movie screens. Then it can't produce movie file as mentioned error above. As I understand, there may be an error relating to using ''fscanf'' to read text file. May be my understanding is wrong so that could any one help me to fix those error and what do exactly they mean?

Thanks Phat

[Walter Roberson]

It was not able to find your resfile to fopen()

You should always test whether the result of fopen() is < 0

[Walter Roberson]

Note that the code

      if i < 10
          resfile = [resroot,'-000',num2str(i),fileex];
      elseif i < 100
          resfile = [resroot,'-00',num2str(i),fileex];
      elseif i < 1000
          resfile = [resroot,'-0',num2str(i),fileex];
      else
          resfile = [resroot,'-',num2str(i),fileex];
      end

can be written much more simply as

     resfile = sprintf('%s-%04d%s', resroot, i, fileex);

Answer 1

[Steven Lord]

Whenever you call fopen in a function I strongly recommend you call it with two outputs and check the first output. If that first output is -1 (indicating fopen was unable to open the file) check the second output. In that case the second output should contain a message offering more information about why fopen was unable to open the file.

The message may give you enough information to determine how to modify your code to avoid the problem. If it doesn't, posting the message here may give the readers enough information to offer suggestions.