2-D colormap (loading .txt files)

I have the following code from my last assignment. The file names and types have been changed. The files like kx 0.txt and kx 10. txt have two lines of data like this

7.49481e+14 0.807996

7.39316e+14 0.798932

7.29422e+14 0.838482

7.1979e+14 0.868927

7.10409e+14 0.880881

I want to plot the first column of data as my y axis, and second column as my x axis, and to combine all files into a 2-D colot map like this (I will change this wavelength in the picture to frequency, and divide the numbers in the first column by 10^12,).

How I may change the lum.y0 into my first column of data and lum.x0 into my second column of data?

filenames={'kx  0.txt','kx 10.txt', 'kx 15.txt','kx 20.txt'} % here i have 50 .txt files like this 
for i=1:numel(filenames)
    
    load(filenames{i});
    %print(filenames{i});
    
    t_data(:,i) = lum.y0
    
end 
angle = linspace(0,0.5,51);
wav_leng = lum.x0.';
figure;
imagesc(angle,wav_leng,t_data); colormap turbo; axis xy;
xlabel('kx')
ylabel('Freqency (THz)')

[DGM]

It's not clear how the files are to be assembled (whether they have the same length and whether the first columns match)

It would be easier if you just zip the files (or a sample of files) and attach it.

Otherwise, if they're all the same size and correspond to the same Y vector, then you should be able to take all the second columns and insert them into a Mx50 array as you work through the loop.

[Chalisa Mawla]

Hi DGM,

All those kx 0. txt/kx 10.txt and such (I have 51 of them) are of same length. the first columns are matching because the data is recorded for the same frequency. I will attach all of them.

[Chalisa Mawla]

Could you please check the attached files? Unfortunately I dont know how to insert them into a Mx50 array..the previous code did it with the lum.y0 and lum.x0

[Katherine Zheng]

Hi Chalisa, your datais quite interesting.From 0-36, the data length is 402 and from 37 onwards, it becomes 201. I am not sure what you are looking for, to extract all the txt file into one matrix?

[Chalisa Mawla]

Hi Katherine,

let me double check on this. I dont think they are of different lengths. Maybe its just the end of the data is all zeros.

Answer 1

[KSSV]

thepath = 'kx values\*.txt' ; 
files = dir(thepath) ;
N = length(files) ; 
data = cell(N,1) ; 
for i = 1:N
    file = fullfile(files(i).folder,files(i).name) ; 
    data{i} = importdata(file) ;     
end
data = cell2mat(data) ; 
x = data(:,2) ; 
y = data(:,1) ; 

[Chalisa Mawla]

>> matrix

Index in position 2 exceeds array bounds.

Error in matrix (line 10)

x = data(:,2) ;

I was getting this error. What does this mean?

[KSSV]

I have not received any error while running the code. For which file you got the error?

[Chalisa Mawla]

It doesnt say

It only says Index in position 2 exceed array bounds.

[KSSV]

It seems, the text file which you are reading has only one column. Check the text file, which shows this error.