Question

Function / File Read (USING MATLAB)

A) create a user-defined function :

[maxsample , maxvalue , numsamples]=writetofile(sname,strgth) to do the following:

The user-defined function shall:

-Accept as the input a provided string for the sample name (sname) and number for strength (strgth)

- open a text file named mytensiledata.txt, with permission to read or append the file.

- Make sure to capture any error in opening the file

- Write sname and strgth to the file

- Close the file

- Open the file again with read access and read the data into memory

- Of the values read, calculate the maximum the strength values and assign the variable : maxvalue

- Assign the sample name with the max strength to the variable: maxsample

- Assign the total number of samples read to the variables : numsamples

B) Calling Script

Create a calling script and call the user function you created (writetofile) four separate times to write the data for each sample to the file mytensildata.txt one at a time. Display the output of writetofile after each call to the function

NOTE: You don't need to use the input() command bring these data in memory

SAMPLE 1, 50.4

SAMPLE 2, 70.5

SAMPLE 3 , 65.3

SAMPLE 4, 100.8

You will likely need to delete mytensildata.txt and run the program one final time to obtain the correct data in the text file. If you get an error while trying to delete .Type close('all') in the command window.

Answer 1

% function writetofile.m
function [maxsample , maxvalue , numsamples] = writetofile(sname,strgth)
fileExists = false;
if(exist('mytensiledata.txt','file'))
fileExists = true;
end
[fid,msg] = fopen('mytensiledata.txt','a+');
if (~isempty(msg))
disp('Error in open file mytensiledata.txt');
else
if(fileExists)
fprintf(fid,'\n%s %f',sname,strgth);
else
fprintf(fid,'%s %f',sname,strgth);
end
fclose(fid);
fid = fopen('mytensiledata.txt','r');
data = textscan(fid,'%s%f');
fclose(fid);
maxsample = data{1}{1};
maxvalue = data{2}(1);
numsamples = 1;
  
for i=2:length(data{1})
numsamples = numsamples + 1;
if(data{2}(i) > maxvalue)
maxvalue = data{2}(i);
maxsample= data{1}{i};
end
end
end
  
end

%end of function

%main script

[maxsample , maxvalue , numsamples] = writetofile("SAMPLE1",50.4);
fprintf('MaxSample : %s MaxValue : %.1f Number of samples : %d\n',maxsample,maxvalue,numsamples);
[maxsample , maxvalue , numsamples] = writetofile("SAMPLE2",70.5);
fprintf('MaxSample : %s MaxValue : %.1f Number of samples : %d\n',maxsample,maxvalue,numsamples);
[maxsample , maxvalue , numsamples] = writetofile("SAMPLE3",65.3);
fprintf('MaxSample : %s MaxValue : %.1f Number of samples : %d\n',maxsample,maxvalue,numsamples);
[maxsample , maxvalue , numsamples] = writetofile("SAMPLE4",100.8);
fprintf('MaxSample : %s MaxValue : %.1f Number of samples : %d\n',maxsample,maxvalue,numsamples);

%end of main script

Output:

Command Line:

MaxSample SAMPLE1 MaxValue 50.4 Number of samples 1 MaxSampleSAMPLE2 MaxValue : 70.5 Number of samples 2 MaxSampleSAMPLE2 MaxValue : 70.5 Number of samples 3 MaxSampleSAMPLE4 MaxValue 100.8 Number of samples : 4

File:

SAMPLE1 50.400000 SAMPLE2 70.500000 SAMPLE3 65.300000 SAMPLE4 100.800000