Convert (seg2read) to (seg2write)

Hi,I have MATLAB code formatted in (seg2read) and I need to modify it to (seg2write); thus, I am asking for your help.

function varargout=seg2read(sg2file, varargin) 
% SEG2READ   Reads SEG-2 format geophysical data (typically Seismic or GPR) 
% Read all wiggles at once 
%   alldata = seg2read(filename); 
% Read every third trace 
%   alldata = seg2read(filename,'traces', [1 3 inf]);  % min, increment, max 
% Various headers are available if wanted. 
%   'data'      2-D maxtrix (trace,sample) of data [default] 
%   'filehdr'   file header (binary) as a structure 
%   'filetxt'   file header (text) as a structure 
%   'trchdr'    trace headers (binary) as a vector of structures 
%   'trctxt'    trace headers (text) as a vector of structures 
%    [filehdr,filetxt,trchdr,data] = seg2read(filename, 'want','filehdr,filetxt,trchdr,data'); 
% Author: Henry Bland, CREWES, University of Calgary 
%
property_strings = ... 
    {'traces','want','verbose'}; 
argout=0; 
verbose = FindValue('verbose',property_strings,varargin{:}); 

if nargin == 0 || isempty(sg2file) 
    [name,path]=uigetfile('*.SG2'); 
    sg2file = fullfile(path,name); 
end 

if ~ischar(sg2file) 
    error('First argument must be a file name'); 
end 

want = FindValue('want',property_strings,varargin{:}); 
if isempty(want) 
    want = 'data'; 
end 



fileinfo = dir(sg2file); % Fileinfo is a structured array of file information. 

if isempty(fileinfo) 
    error(['The file ', sg2file, ' does not exist.']) 
end 

fileinfo.bytes; % Pull the size of the file out of fileinfo. 

gotDataFormat = 0; 
byteOrder = 'le';   % Big-endian byte order 

fid = fopen(sg2file, 'r', ['ieee-' byteOrder]);% Open the segy file for reading. 

if fid == -1 
    error('Unable to open file.') 
end 

filehdr = readFileDescriptor(fid); 
if filehdr.file_descriptor_id ~= hex2dec('3a55'); 
    error(['Invalid file descriptor: corrupted file? ' sg2file]); 
end 

ntraces = filehdr.number_of_traces_in_file; 

traceDescPtr = readTraceDescriptorPointers(fid, ntraces); 

filetxt = readFileParams(fid, filehdr.size_of_trace_pointer_subblock); 

% If we want to get traces in some funny order, or skip some, 
% we just use a different "wantedTraces" (e.g. 1:3:128) 
traces = FindValue('traces',property_strings,varargin{:}); 
if isempty(traces)  
    wantedTraces = 1:ntraces; 
else 
    if length(traces) < 2 
        traces(2) = 1; 
    end 
    if length(traces) < 3 
        traces(3) = inf; 
    end 
    wantedTraces = traces(1):traces(2):min(ntraces,traces(3)); 
end 

% Here, trace is the sequence number in the ensemble 
for seqno=1:length(wantedTraces) 
    traceInFile = wantedTraces(seqno);   % often the same thing as seqno 
    th = readTraceHeader(fid, traceDescPtr(traceInFile)); 
    trchdr(seqno) = th; 
    if trchdr(seqno).trace_descriptor_id ~= hex2dec('4422'); 
        error(['Invalid trace descriptor: corrupted file? ' sg2file]); 
    end 
    trctxt(seqno) = readParamStrings(fid); 
    advanceToNextWord(fid); 
    switch trchdr(seqno).data_format_code 
        case 1 
            data(:,seqno) = fread(fid,trchdr(seqno).number_of_samples,'int16=>double'); 
        case 2 
            data(:,seqno) = fread(fid,trchdr(seqno).number_of_samples,'int32=>double'); 
        case 3 
            error(['seg2read does not support 20 bit floating point data']); 
        case 4 
            data(:,seqno) = fread(fid,trchdr(seqno).number_of_samples,'float=>double'); 
        case 5 
            data(:,seqno) = fread(fid,trchdr(seqno).number_of_samples,'double=>double'); 
        otherwise 
            error(['data format 'trchdr(seqno).data_format_code ' is not supported']); 
    end 
end 
fclose(fid); 

[wanted, want] = strtok(want,','); 
arg=1; 
while ~isempty(wanted) || ~isempty(want) 
    switch wanted 
        case 'data' 
            varargout{arg} = data; 
        case 'trchdr' 
            varargout{arg} = trchdr; 
        case 'trctxt' 
            varargout{arg} = trctxt; 
        case 'filehdr' 
            varargout{arg} = filehdr; 
        case 'filetxt' 
            varargout{arg} = filetxt; 
        otherwise 
            error('invalid value for "want" parameter. Must be one of: data,trchdr,trctxt,filehdr,filetxt'); 
    end 
    arg = arg+1;     
    [wanted, want] = strtok(want,','); 
end 

    function advanceToNextWord(fid) 
        % advances the file pointer to a 32bit word-aligned  
        % position in file (a position evenly divisible by 4) 
        pos = ftell(fid); 
        inc = mod(4-mod(pos,4),4); 
        if inc 
            fseek(fid, pos+inc, 'bof'); 
        end 
    end 


    function trchdr = readTraceHeader(fid, ptr) 
        fseek(fid, ptr, 'bof'); 
        trchdr.trace_descriptor_id = fread(fid, 1, 'uint16')'; 
        trchdr.size_of_this_block = fread(fid, 1, 'uint16'); 
        trchdr.size_of_following_data_block = fread(fid, 1 ,'uint32'); 
        trchdr.number_of_samples = fread(fid, 1 ,'uint32'); 
        trchdr.data_format_code = fread(fid, 1, 'uint8'); 
        trchdr.reserved = fread(fid, 19, 'uint8'); 
    end 


    function fileParams = readFileParams(fid, size_of_trace_pointer_subblock) 
        size_of_file_header = 32; 
        fseek(fid, size_of_trace_pointer_subblock + size_of_file_header, 'bof'); 
        fileParams = readParamStrings(fid); 
    end 

    function traceDescPtr = readTraceDescriptorPointers(fid, ntraces) 
        traceDescPtr = fread(fid, ntraces, 'uint32'); 
    end 

    function params = readParamStrings(fid); 
        len = fread(fid, 1, 'int16'); 
        params = struct(); 
        while len > 0 
            s = fread(fid, len - 2, 'char=>char')'; 
            [name, value] = processParamString(s); 
            params = setfield(params, lower(name), value); 
            len = fread(fid, 1, 'int16'); 
        end 
    end 

    function [name, value] = processParamString(s) 
        [name, value] = strtok(s,' '); 
        value(1) = []; 
    end 

    function filehdr = readFileDescriptor(fid) 
        filehdr.file_descriptor_id = fread(fid, 1, 'uint16')'; 
        filehdr.revision_number = fread(fid, 1, 'uint16'); 
        filehdr.size_of_trace_pointer_subblock = fread(fid, 1 ,'uint16'); 
        filehdr.number_of_traces_in_file = fread(fid, 1 ,'uint16'); 
        filehdr.size_of_string_terminator = fread(fid, 1, 'uint8'); 
        filehdr.first_string_terminator = fread(fid, 1, 'uint8'); 
        filehdr.second_string_terminator = fread(fid, 1, 'uint8'); 
        filehdr.size_of_line_terminator = fread(fid, 1, 'uint8'); 
        filehdr.first_line_terminator = fread(fid, 1, 'uint8'); 
        filehdr.second_line_terminator = fread(fid, 1, 'uint8'); 
        filehdr.reserved = fread(fid, 18, 'uint8=>uint8'); 
    end 

% ----------------------- 
    function value = FindValue( property_name, property_strings, varargin ) 
        
        value = []; 
        for i = 1:((nargin-2)/2) 
            current_name = varargin{2*i-1}; 
            if ischar(current_name) 
                imatch = strmatch(lower(current_name),property_strings); 
                nmatch = length(imatch); 
                if nmatch > 1 
                    error(['Ambiguous property name ' current_name '.']); 
                end 
                if nmatch == 1 
                    canonical_name = property_strings{imatch}; 
                    if strcmp(canonical_name, property_name) 
                        if isempty(value) 
                            if isempty(varargin{2*i}) 
                                error(['Empty value for ' property_name '.']); 
                            end 
                            value = varargin{2*i}; 
                        else 
                            error(['Property ' property_name ' is specified more than once.']); 
                        end 
                    end 
                end 
            end 
        end 
    end 
%--------------------- 

    function value = BooleanValue(x) 
        
        if ischar(x) 
            x = lower(x); 
            value = strcmp(x,'yes') | strcmp(x, 'on') | strcmp(x, 'true'); 
        elseif ~isempty(x) & isnumeric(x) 
            value = (x ~= 0); 
        else 
            value = 0; 
        end 
    end 

end

[dpb]

That's a little more than asking for some help to offload the entire task...

I'd think the folks who wrote this function would have the complement as well; I'd suggest there would be the place to start.

[dpb]

Well, it appears Mr Bland has moved on from U of Calgary and a (very quick) search there didn't uncover anything (not that it isn't there, I certainly didn't search thoroughly).

Mr Gargle located https://ge0mlib.com/software.htm#FreeMatLabGeoNav that may be useful starting point or may just have something can use directly, who knows?

I also saw some links that indicate there may be some other functions at the FileExchange.

[Jan]

What have you tried so far? What exactly is your question?

Some hint to the shown code:

• Do not use "path" as name of a local variable, because it is an important Matlab function. During debugging this could damage your setup.
• Avoid including file names in error message directly:

error(['The file ', sg2file, ' does not exist.'])

Remember that the char vector is interpreted and if it contains a % character strange thing will happen. Safer:

error('The file %s does not exist.', sg2file)

Answer 1

[Mohammed Adam]

Currently, my data is in (.dat) format, and I need to use this code to call the (.dat) in order to convert it to (seg2) format.

[Jan]

Pleae post comments in the sections for comments, not as an answer.

There is no specific ".dat" format, therefore "my data is in (.dat) format" does not clarify anything.

Did you search for specifications of the seg2 format in the internet already? Then it would be useful, if you post a link instead of letting the readers search by their own.

It is unlikely that somebody implements the code for you. This is more work than usually spent to write an answer. In addition there wil be many exceptions, e.g. Unicode characters in the comments etc. Without knowing what you exactly need, it is impossible to write a reliable code.

So either try it by your onw and ask specific questions here, or hire a professional programmer.