How do i get a function to open any text file on a computer

Hi,

I have written the code below and i was wondering how i could get the function to open any txt file on the pc not just the one i assigned. So if i implemet a GUI to call up this fuction for any data it will read it?

function Sensor_data();
fid = fopen ('Gradual opening of tap.txt');
initial_line = fgetl(fid);

%Variables for the data (Garvity, Volts of the pump, and the Density of
%water)
data_figure();
current_time = 0;
gravity = 9.81;
vs = 5;
density = 997;

%While loop for for working out the data from each line of data and
%ploting the data.

while ischar(initial_line)
    data = sscanf(initial_line,'%f V, %d counts, %d ms');
    
    %extarctting the data from the file and unpacking it by line.
    
    v = data(1);        %volts
    pulses = data(2);   %amount of plulse
    t = data(3);        %time intervals
    
    %   calculating the remainder of the data to be plotted
    
    current_time = current_time + t;
    P = ((v/vs)-0.04)/0.0018;
    h = P*1000/(density*gravity);
    Q = (1000*pulses)/(330*current_time);
    hydraulic = (Q*P)/1000;
    
    plot_data(hydraulic,current_time,h,P,Q)
    
    initial_line = fgetl(fid);
    
end

% Function for plotting figures for each individual graph

    function data_figure()
        figure(1)
        clf
        %Pressure (P) v Time(current_time) data plot
        subplot(2,2,1)
        hold on
        grid on
        title ('Pressure v Time')
        xlabel('Time(ms)')
        ylabel('Pressure (Pa)')
        %Flow rate (Q) v Time (current_time) data plot
        subplot(2,2,2)
        hold on
        grid on
        title ('Flow rate v Time')
        xlabel('Time(ms)')
        ylabel('Flow  (L/ms')
        %Flow rate (Q) v Head pressure (h)
        subplot(2,2,3)
        hold on
        grid on
        title ('Flow Rate v Head Pressure ')
        xlabel('Flow (L/ms)')
        ylabel('Pressure (Pa)')
        %Hydraulic Power (hydraulic) v Flow rate (Q) data plot
        subplot(2,2,4)
        hold on
        grid on
        title ('Hydraulic Power v Flow Rate')
        xlabel('Power(W)')
        ylabel('Flow (L/ms)')
    end
    function plot_data(hydraulic,current_time,h,P,Q)
        
        subplot(2,2,1);
        scatter(current_time,P)
        subplot(2,2,2);
        scatter(current_time,Q)
        subplot(2,2,3);
        scatter(Q,h)
        subplot(2,2,4);
        scatter(Q,hydraulic)
        drawnow;
        
    end
end

[Stephen23]

Why not just supply the filename/path as an input argument? I.e. instead of this:

function Sensor_data();
fid = fopen ('Gradual opening of tap.txt');

simply do this:

function Sensor_data(file);
fid = fopen(file);

And then just call your function with whatever filename/path you want.

Although beginners like sticking UI controls inside functions, I would recommend avoiding doing that if you are interested in writing clear, efficient, testable code.

Important: Note that you should fclose every file that you fopen. Accumulating handles to open files can slow down MATLAB and can lead to it crashing.

[Juan Palacios]

Doesnt work, not enough imput arguments for the fuction.

[Jan]

How do you start the function? By pressing the "Run" button in the editor? If you define the function with an input argument, you have to call it with an input argument also:

Sensor_data('YourTextFile.txt')

Answer 1

[Jan]

function Sensor_data()
[fileName, filePath] = uigetfile('Choose some Sensor data:');
if isequal(fileName, -1)
    disp('User aborted file choosing');
    return;
end

file = fullfile(filePath, fileName);
... Your code

[Juan Palacios]

Is that for the GUI intergration or to run any file? That code would not work as i need it to ananlyse the data on each line of the file and scatter plot each entry being updated. The data is in a text file.