read struct from a file

[Hailin Shen]

Dear all,

Is there an easy way to read a structure,e.g. file header, from a file into
Matlab?

regards

Hailin

[Steven Lord]

Hailin Shen wrote:
> Dear all,
>
> Is there an easy way to read a structure,e.g. file header, from a
> file into Matlab?

It depends. What file format are you trying to read? If you're reading in
a plain text file, DLMREAD or TEXTREAD may help you out. Excel file? See
XLSREAD. Binary file for which you know the format? FSCANF and the
low-level I/O functions listed in the "Formatted file I/O" section of HELP
IOFUN will be useful. [Binary file for which you _don't_ know the format?
That's tricky.]

I'd suggest if none of these work to look through HELP IOFUN and see if one
of the functions listed therein works on your file format.

--
Steve Lord
sl...@mathworks.com

[Alex Dannenberg]

What is XLSREAD and where can it be found... I'm running version 5.2 plus
some toolboxes and I don't have it...

-Alex Dannenberg
Al...@PineMountainCapital.com

"Steven Lord" <sl...@mathworks.com> wrote in message
news:ap17vq$fmt$1...@news.mathworks.com...

[Ken Davis]

"Hailin Shen" <h.s...@umist.ac.uk> wrote in message
news:3db409a9$1...@news.umist.ac.uk...

Hello,

Here is a function that will read data from a file into a structure. The
rows of the file must be field and subfield names with the last entry of the
row being a value. For example, if the rows of myfile.txt file are:

test1 3.141
test2 test3 'pi'
test4 pi

The the command below will give the result shown:

>> s = readstruct('myfile.txt')

s =

test1: 3.141
test2.test3: 'pi'
test4: 'pi'

I hope this might be useful to you.

Regards,

Ken

Here's the function:

function s = readStruct(file)
% READSTRUCT(FILE) Reads structure from text file, FILE.
% The last entry in each row is the value. The previous
% entries are field (and subfield) names.

% Open the specified file.
fid = fopen(file);

% Read in the first line and set the line number.
line = fgetl(fid);

% The function, fgetl, returns a -1 when an end-of-file is encountered.
while ~isequal(line, -1);

% Initially, no items from this line
items = {};

% Number of items extracted from this line.
numberOfItems = 0;

% While there is still some path left, keep parsing nodes into a cell
array.
while line
numberOfItems = numberOfItems + 1;
[items{numberOfItems}, line] = strtok(line);
end

% Only process non-empty lines.
if numberOfItems > 1

% Last item on line is value of field. If first element of last item
is a letter,
% then assume that last item is a char array. Otherwise, assume it
is a number.
if isletter(items{end}(1))
value = ['''', items{end}, '''']; % Wrap quotes around string.
else
value = items{end};
end

% remove value from list of items (leaving only field names).
items = items(1:length(items)-1);

fieldname = 's'; % Initialize construction of field name.
for item = items
fieldname = [fieldname, '.', item{:}]; % Append subfield names
to field name.
end

% Construct command to assign value to field name.
command = [fieldname, ' = ', value, ';'];

eval(command);

elseif numberOfItems == 1;

error ('Every non-empty line must contain must contain at least one
field name and one value.')

end

line = fgetl(fid);

end

fclose(fid);

[Lars Gregersen]

On Mon, 21 Oct 2002 14:36:48 +0100, "Hailin Shen" <h.s...@umist.ac.uk>
wrote:

>Dear all,
>
>Is there an easy way to read a structure,e.g. file header, from a file into
>Matlab?

It most certainly depends on the structure :-) of the file. If the
structure is complex the command to read the file will probably be
complex too.

Perhaps a combination of fread and strread will help you?!?!

Lars

Lars Gregersen
www.rndee.dk
l...@rndee.dk