how to solve "Subscripted assignment dimension mismatch" error?

Hi everyone, any help on this will be highly appreciated!!

Here is my program:

fid = fopen('test.cal'); 

[paramlist l] = textscan(fid, '%s %s %s %s %s'); %paramlist is a variable

fclose(fid);

[len wid] = size(paramlist{1}); %len=3, wid=4

chanlist = zeros(3,4); %chanlist is a variable

chanlist(1,1:4) = [paramlist{2}{1},paramlist{3}{1},paramlist{4}{1},paramlist{5}{1}]; %write the info from the test.cal into the 1st row of matrix, chanlist. Error happen due to this line.

Here is the "test.cal" file:

channel DIGOUT 0 0 shutter1 

channel DIGOUT 0 1 shutter2 

channel DIGOUT 0 2 shutter3

When I run the program, the error "subscripted assignment dimension mismatch" will show up, I really dont know how resolve it.

[Jan]

Are there empty lines between the lines in your file?

[Walter Roberson]

It turns out not to matter if there are blank lines if you are using %s format: %s skips leading whitespace (just like the number formats do), so textscan() would skip over the blank lines.

[Jan]

@Walter: Correct. I just wanted to be sure, that we are talking about the same problem.

@Yu Wang: The problem gets obvious, if you try to run your program line by line. Most of all running "[paramlist{2}{1},paramlist{3}{1},paramlist{4}{1},paramlist{5}{1}]" in the command window reveals the error.

It is a good idea to perform some debugging, when a problem occurs...

Answer 1

[Walter Roberson]

chanlist = zeros(3,4); defines chanlist to be a numeric variable.

paramlist{2}{1} extracts the string from paramlist{2}{1}, which should be 'DIGOUT' . Strings in MATLAB are row vectors of characters.

[paramlist{2}{1},paramlist{3}{1},paramlist{4}{1},paramlist{5}{1}] likewise extracts all the strings from remaining cells. So at this point you are constructing

['DIGOUT','0','0','shutter1']

The result of applying the [] list-building operator to a series of row vectors of characters, is a row vector containing all of the characters, so this expression is going to construct

'DIGOUT00shutter1'

and then you attempt to assign these 16 characters in to the 4 numeric locations chanlist(1,1:4) . Assigning characters to numeric locations is well-defined, with each character corresponding to the value of the character's ordinal number (e.g., '0' happens to be ordinal 48, char(48) == '0'), so the character to numeric assignment is merely going to startle you rather than crash your code -- but you need as many storage locations as you have characters.

It is difficult to tell what you want to do, but I suspect it would be

chanlist = cell(size(paramlist) - [0 1]);
for K = 1:size(paramlist,1)
  chanlist(K,:) = paramlist(K,2:end);
end

Which could be done more simply as

chanlist = paramlist(:,2:end);

[Yu Wang]

Thank you very much. In fact what I am trying to do is write all the info of "test.cal" file into a single variable so that I could use the info of it when this m-file is called by another m-file (im a totally a rookie, I guess). It could be anything, and in this case, I used matrix of zeroes which seems not be a wise choice. Could you give me any advice on this? Thank you very much.

[Walter Roberson]

chanlist = paramlist(:,2:end);

copies all of the information except the "channel" word.

What format does the second m-file expect to receive the data in?

Do each of the string fields have a limited number of possible values? If so then do you want to encode the string for that field as a numeric value that represents which of the strings was read? If so then the file contents could plausibly be encoded to a numeric matrix.

For example,

[tf, caldirs] = ismember(paramlist{2}, {'DIGIN', 'DIGOUT'});

calfield3 = str2double(paramlist{3});

calfield4 = str2double(paramlist{4});

[tf, calshut] = ismember(paramlist{5}, {'shutter1', 'shutter2', 'shutter3', 'shutter4', 'shutter5'});

chanlist = [caldirs(:), calfield3(:), calfield4(:), calshut(:)];

and then chanlist would be a something-by-4 numeric matrix, with 1 in the first column meaning 'DIGIN', 2 there indicating 'DIGOUT', and so on.