how to extract coordinates from g code files

Hi, I asked another question similar to extraction of external edges coordinates from g code files - MATLAB Answers - MATLAB Central (mathworks.com) why I was not clear enough.

I have this text file (g code), with several lines. What I would like to do is read the lines considering only some of them and extract the X Y E coordinates from them. In particular, the text is divided into "sections": it contains the coordinates for 3D printing of 3 parts (3 types of MESH) and for each part the external wall (WALL-OUTER) and the internal matrix are identified. This is for each single LAYER deposited by the extruder. (MESH, WALL-OUTER and LAYER are keywords present in the text)

My goal is to extract the coordinates X Y E referred to

MESH: lattice1, dim elem 0.98, rotaz 30.stl

TYPE: WALL-OUTER

and this for every single LAYER

I want to extract coordinates from G lines between these keywords

I tried to use this script but there is something wrong

filename = 'file g.gcode';
output = strcat('modified', filename);
fid = fopen (filename, 'r');
fod = fopen (output, 'wt');
rgx = [';LAYER ^M\s+S(\S+) ;TYPE:WALL-OUTER ;MESH:lattice1, dim elem 0.98, rotaz 30.stl ^G1\s+X(\S+)\s+Y(\S+)\s+E(\S+)'];

percent = 0.2
text = readlines(filename);

while ~feof (fid);
    str = fgetl(fid);
    [spl, tkn] = regexp (str, rgx, 'split', 'tokens', 'once'); %seperates numbers from text
    vec = str2double(tkn);%converts number (text) into number values
    if numel(vec);
        vec = vec + percent*numel(vec);
        mod = sprintf ('G1 X%g Y%g E%g', vec);
        fprintf ('og: %s\nnew: %s\n\n', str, mod);
        spl {2, 1} = mod;
        spl(cellfun(@isempty, spl)) = [];
    end
    fprintf (fod, '%s\n', spl{:})
end

[Federico Paolucci]

@Walter Roberson Good Morning, in your opinion can I modify to script above to obtain the result that I want? Grazie

[Walter Roberson]

rgx has four (\S+) so it should be outputing four tokens, so vec should have four entries if the line matched. But your sprintf line only has three %g formats, so the format would have to be repeated automatically for the 4th entry. Are you sure that is what you want? And if it is, why not just code the 4th %g format for clarity ?

[Federico Paolucci]

Ok I correct, only that the script does not work because it continues to output the same lines as the input g file, while I would like to extract the X Y E coordinates corresponding to the type WALL-OUTER of the part to be printed "lattice1, dim elem 0.98, rotaz 30.stl "and this for each LAYER

[Federico Paolucci]

@Walter Roberson I extracted ALL the coordinates X Y E from the gcode file with this script

str = fileread('file g.gcode');
rgx = sprintf('\\s+%c([+-]?\\d+\\.?\\d*)','XYE');
tkn = regexp(str,rgx,'tokens');
mat = str2double(vertcat(tkn{:}))

but I want ONLY the coordinates that are written under the lines:

;MESH: lattice1, dim elem 0.98, rotaz 30.stl

;TYPE: WALL-OUTER

Answer 1

[Mathieu NOE]

hello

tried a few things , this is my suggestion for the time being . Not 100% sure it's the best code , maybe someone else will see potential improvements.

have identified 75 "valid" sections as I assumed what we are loocking for are the data that follows the two lines (in that specific order) :

;TYPE:WALL-OUTER

;MESH:lattice1, dim elem 0.98, rotaz 30.stl

those 75 sets are stored individually in a cell array (mat)

hope it helps !

clc
clearvars

D=readlines('file g.gcode');                                             % read as string array

ixMESH=find(contains(D,';MESH:lattice1, dim elem 0.98, rotaz 30.stl'));     % find the "MESH" lines
ixTYPE=find(contains(D,';TYPE:WALL-OUTER'));                                % find the "TYPE:WALL-OUTER" lines

eof = numel(D); 

% I want ONLY the coordinates that are written under the lines:
% ;MESH: lattice1, dim elem 0.98, rotaz 30.stl 
% ;TYPE: WALL-OUTER

% In fact portion of data is organized either after two consecutives lines :
% 
% ;TYPE:WALL-OUTER
% ;MESH:lattice1, dim elem 0.98, rotaz 30.stl

% the other case being : 
 % example 1 : 
%  ;MESH:lattice1, dim elem 0.98, rotaz 30.stl
% G0 F1285.7 X186.285 Y123.676
% G0 X184.711 Y123.546
% G0 X181.241 Y123.546
% G0 X174.446 Y123.619
% G0 X171.19 Y123.546
% M204 S1000
% ;TYPE:WALL-OUTER

% example 2
% ;MESH:lattice1, dim elem 0.98, rotaz 30.stl
% G0 F9000 X184.711 Y123.684
% G0 X181.241 Y123.684
% G0 X174.431 Y122.806
% G0 X170.914 Y123.684
% ;TYPE:WALL-OUTER

% notice the distance between the two lines vary in case 2 which makes
% things a bit more complicated

%% for the time being the code below works (hopefully) for case 1 where lines come in this order (and consecutives)
% ;TYPE:WALL-OUTER
% ;MESH:lattice1, dim elem 0.98, rotaz 30.stl

ixTYPE(ixTYPE>ixMESH(end)) = []; % remove ixTYPE greater than last value of ixMESH
ixMESH(ixMESH<ixTYPE(1)) = []; % remove ixMESH below fist value of ixTYPE

% define which sections are candidates (mst have the two lines in
% consecutive order) :
ixTYPE_select = [];

for ci = 1:numel(ixTYPE)
    ind = find(ixMESH>ixTYPE(ci),1,'first');
    delta = ixMESH(ind) - ixTYPE(ci) ;
    if delta == 1
        ixTYPE_select = [ixTYPE_select ; ixTYPE(ci)];
    end
end

% loop over the selected portion of file
for ci = 1:numel(ixTYPE_select)
    if ci == numel(ixTYPE_select) % last file section until EOF
         str = convertStringsToChars(D(ixTYPE_select(ci):eof,1)); % selected portion of text 
    else  % previous sections
        str = convertStringsToChars(D(ixTYPE_select(ci):ixTYPE_select(ci+1),1)); % selected portion of text 
    end
    % your code expanded below
    rgx = sprintf('\\s+%c([+-]?\\d+\\.?\\d*)','XYE');
    tkn = regexp(str,rgx,'tokens');
    % remove empty cells
    emptyCells = cellfun('isempty', tkn);
    tkn(emptyCells) = [];
    % convert cell array of cells to one array 
    A = vertcat(tkn{:});
    B = vertcat(A{:});
    mat{ci,1} = str2double(B); % finally ! store the array in one cell (or whatever structure you prefer

    
end

[Federico Paolucci]

Hi @Mathieu NOE thanks for your script! Below, I report a more accurate description of that I want (maybe my previous description is not 100% clear)

I want to obtain is a script capable of loading the g code and dividing it into a structure with cells containing the individual commands: I want to find the strings in which the outer contour of all layers is drawn, initialized by ;TYPE: WALL-OUTER, as a result of which all commands containing the token G1 at the beginning of the command are stored, followed by the X Y Z E coordinates of displacement and possibly also from F. Then, also commands with the token G0 are stored. I should therefore extract the absolute position coordinates, saved in a structure cataloged by layer to which it belongs. the points extracted from the g code must be ordered in order to have a closed path that can be represented by a polygon. the passage from one layer to the next must be indicated by the ;LAYER string, followed by the layer number starting from 0 and the height expressed in mm must be indexed in the first strings of the file through the comment; layer height, for example 0.2 mm. In the g code file there are the coordinates for each piece to be printed, they are distinguishable as the construction of the layer is preceded by the string ;MESH. In particular I want to extract the coordinates for the piece "lattice1, dim elem 0.98, rotaz 30", so it is necessary to locate the string ;MESH: lattice1, dim elem 0.98, rotaz 30.stl

[Mathieu NOE]

hello Federico

ok - need more time to diggest all these infos - but this gonna take a while to be finalized and checked ... this is probably a work for a subcontractor rather than some hobbyist (like myself) that spend a few minutes per day on this forum.

[Federico Paolucci]

Thank you for your availability!

[Mathieu NOE]

maybe one thing you could do is paste your g code in word or excel and put some color where you want the data

that would help to visualize which sections you want to retrieve (sometimes more efficient than a long description)