replace a random number in a line of a text file

how can I replace random number (with 'randi()' commond) in a text file? for example I want replace "1.035" in the below line with a random number:

"x coordinate = 1.035"

Answer 1

[Walter Roberson]

In the below, the isunix() branch is to put in example text since I do not have a file to work with. In your actual code, you would just have the fileread() without the if isunix()

filename = 'example.txt';
outfilename = 'modified.txt';

if isunix()
    S = sprintf('Number of nodes: 5\nx coordinate = 1.035\ny coordinate = -3.873\n')
else
    S = fileread(filename);
end

S = 
    'Number of nodes: 5
     x coordinate = 1.035
     y coordinate = -3.873
     '

newvalue = string(10*randn(1,1))

newvalue = "1.9462"

newS = regexprep(S, '(?<=x coordinate = )(-?[\d.]+)', newvalue)

newS = 
    'Number of nodes: 5
     x coordinate = 1.9462
     y coordinate = -3.873
     '

[fid, msg] = fopen(outfilename, 'w');
if fid < 0; error('could not open output file "%s" because "%s"', outfilename, msg); end
fwrite(fid, newS);
fclose(fid)

ans = 0

dbtype(outfilename)

1     Number of nodes: 5
2     x coordinate = 1.9462
3     y coordinate = -3.873

[sajad mhmzd]

thanks man

[sajad mhmzd]

I wrote my own code for replacing a Num in a string but there is a problem. in the second loop the number 12 replace with 132 insted of 13 and i've been confused.

F = 'bodyNameRefManager_1.setBodies(new NeoObjectVector(new Object[] {}));';

for i=12:13

str_e = sprintf('bodyNameRefManager_%0.0f',i);

new = regexprep(F,'bodyNameRefManager_(\w)', str_e)

F = new;

end