how to extract data from ascii file?

i have been given ascii file ..

how to read data from it and plot the graphs

in this file around 2000 data is present ...and i need only 1001 data in such a way that i don't lose the entire data only some of them.

for example from freq=8-12GHz there are data like

freq parameter

8 -0.00000003

8.001 -0.2233652

8.002 -2.0000012

;

;

10.222 -2.22333

;

;

12 -2.0001123

so basically from 8-12 GHz all the data but losing very few data

2018a version

[Stephen23]

@Rakesh Roshan: please upload a sample data file by clicking the paperclip button.

[Rakesh Roshan]

i have uploaded the data sir

Answer 1

[Voss]

data = readmatrix('qwer.txt')

data = 31×2

8.0000 0.0003 8.0100 0.0003 8.0200 0.0003 8.0300 0.0003 8.0400 0.0004 8.0500 0.0004 8.0600 0.0004 8.0700 0.0004 8.0800 0.0006 8.0900 0.0008

plot(data(:,1),data(:,2),'.-')

"in this file around 2000 data is present ...and i need only 1001 data"

data = data(1:2:end,:) % keep rows 1, 3, 5, ...

data = 16×2

8.0000 0.0003 8.0200 0.0003 8.0400 0.0004 8.0600 0.0004 8.0800 0.0006 9.0000 0.0009 9.0200 0.0001 9.0400 0.0006 9.0600 0.0004 9.8000 0.0045

hold on
plot(data(:,1),data(:,2),'or')

[Rakesh Roshan]

thank u sir but my concern is i am generating lot of data of ascii files for approx 2000 simulations..each simulation many data in that case no of data in each text files will vary ...

is there any way where only fixed number of data i can extract

[Voss]

Please see this answer:

https://www.mathworks.com/matlabcentral/answers/57446-faq-how-can-i-process-a-sequence-of-files#answer_69523

You can alter the code to read just the files you want.

[Voss]

For instance, you might store Freq and Sparamters from the files in separate fields in the struct array returned from dir:

files = dir('*.txt');
disp({files.name});

    {'qwer.txt'}    {'qwer2.txt'}    {'qwer3.txt'}

files = files(1:2:end); % just keep every other file: files(1), files(3), ...
disp({files.name});

    {'qwer.txt'}    {'qwer3.txt'}

for ii = 1:numel(files)
    temp = readmatrix(files(ii).name);
    files(ii).xdata = temp(:,1);
    files(ii).ydata = temp(:,2);
end

plot_args = [{files.xdata}; {files.ydata}];
plot(plot_args{:});