How do you plot sequentially numbered files on one plot?

I am new to MATLAB and have created ascii folders with 30 .asc files in each that I would like to plot on one graph. I have tried to figure out how to do this, but have a limited understanding of MATLAB. I know I need to include the matrix size (200:1), but this is actually 2 columns with x,y values in it.

So far all I have is:

 Files = ('sample1_1_*.asc');

 clf,figure,hold on;

 for k = 1:30
    plot(Files(k,:))
 end

But this gives an error of 'Index exceeds matrix dimensions.'

Any help would be much appreciated or if you could direct me to a relevant post that would be fantastic!

[OCDER]

Matlab does not use zero-indexing. Try k = 1:30 instead.

[S B]

It now comes up with the error 'Index exceeds matrix dimensions.'

[OCDER]

It's caused because the file name is just a 1-line string in matlab. "Files" does not store the 30 asc file names correctly (hence you'll get an index exceed error). I think I can give you a function that'll work, but could you copy and paste just the first 5 data points for one asc file that you want to plot? Just so I can see if matlab has the right file reader.

Answer 1

[OCDER]

Assuming your asc txt files stores the data in the following pattern:

x y

x y

x y

Save the following functions as plotAscData.m, and run plotAscData

> plotAscData

function plotAscData
%Select multiple files and store the file name into a cell array
[FileName, FilePath] = uigetfile('*.asc', 'Open files', 'multiselect', 'on');
if ischar(FileName) 
    FileName = {FileName};
elseif isnumeric
    warning('No file selected');
    return;
end

figure;
hold on;
for f = 1:length(FileName)
    FullFileName = [FilePath FileName{f}];
    M = readAscFile(FullFileName); %Reads csv file as a matrix
    x = M(:, 1); %Assuming x values are the 1st column
    y = M(:, 2); %Assuming y values are the 2nd column
    plot(x, y);
end
hold off;

function M = readAscFile(AscFileName)
FID = fopen(AscFileName, 'r'); %Access asc file

%Count number of columns, if possible
if feof(FID) == 0 
    TextLine = fgetl(FID);
    NumCol = length(regexpi(TextLine, '\s', 'split')); 
else %Nothing in this file
    warning('File is empty.');
    M = [];
    return;
end

fseek(FID, 0, 'bof'); %Return to file beginning
FileStrFormat = repmat('%f', 1, NumCol); %Specify asc data format
ScannedText = textscan(FID, FileStrFormat); %Read the data into a cell array

%Convert the ScannedText cell array into the double array M
M = zeros(length(ScannedText{1}), NumCol); %Preallocate double matrix M
for j = 1:NumCol 
    M(:, j) = ScannedText{j};
end

fclose(FID); %Close file to free up memory

[S B]

Thanks for this! It only plots one straight diagonal line though? Is this because the files are in columns of:

x y
x y
etc?

[OCDER]

Yup, that would have caused the line issue. The new code is fixed now. It assumes you have a 2-column asc data file. There are 2 functions, but you can just copy and paste all to the M editor and save it as a single plotAscData.m file.

[OCDER]

And as Walter said, the asc file format may differ. Change

FileStrFormat = repmat('%f', 1, NumCol);

depending on what your data structure is. I'm assuming you only have double values, hence I'm using '%f'. Also, I'm assuming your file has no delimiter, other than white space, hence I'm using '\s' in

NumCol = length(regexpi(TextLine, '\s', 'split'));

to count how many data columns you have. That may not always be the case. Best of luck!

[S B]

Thanks so much for this! In the end, a combination of the 2 worked for me:

    %Select multiple files and store the file name into a cell array
    [FileName, FilePath] = uigetfile('*.asc', 'Open files', 'multiselect', 'on');
    if ischar(FileName) 
        FileName = {FileName};
    elseif isnumeric(FileName)
        error('No file selected');
    end
    figure;
    hold on;
    for f = 1:length(FileName)
        FullFileName = [FilePath FileName{f}];
        M = dlmread(FullFileName); 
        x = M(:, 1); %Assuming x values are the 1st column
        y = M(:, 2); %Assuming y values are the 2nd column
        plot(x, y);
    end
    hold off;

Are you self taught? Can you recommend any literature/courses?

Thanks again!

[OCDER]

Glad that you got it to work! I did take a course in college Intro to Matlab, but I'd say 95% self taught. I do what you do - peruse the Q & A section in this website, use the help function A LOT, and try opening and understanding some of matlab built-in codes (which are made by VERY experienced people). Considering you're able to understand and adjust my code to make it work, you're doing great!

Answer 2

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

[S B]

Hi Walter,

Thanks for this; I had just found this too, but have trouble as my files are .asc and everything is tailored to other file formats; am I overlooking something?

[Walter Roberson]

.asc is not a standardized file format. We would need to know the data format in the files. Is there a header? How many columns? What is the delimiter between the columns?