I do matlab operation with two data file whose entries are complex numbers. For example,
fName = '1corr.txt';
f = dlmread('1EA.txt',',');
fid = fopen(fName);
tline = '';
Then I do matrix and other operations between these two files and write my output which I call 'modTrace' as:
modTrace
fileID = fopen('1out.txt','w');
v = [(0:(numel(modTrace)-1)).' real(modTrace(:)) ].';
fprintf(fileID,'%d %e\n',v);
The question is, if I have for example 100 pairs of such data files, like (2corr.txt, 2EA.txt), ....(50corr.txt, 50EA.txt) how can I generalize the input files and how to write all the output files at a time?
First of all, use sprintf to get your variable names depending on the current index.
corrName=sprintf('%dcorr.txt',idx);
EAName=sprintf('%dEA.txt',idx);
outName=sprintf('%dout.txt',idx);
This way, you have one variable (idx) which has to be changed.
Finally put everything into a loop:
n=100
for idx=1:n
corrName=sprintf('%dcorr.txt',idx);
EAName=sprintf('%dEA.txt',idx);
outName=sprintf('%dout.txt',idx);
f = dlmread(EAName,',');
fid = fopen(corrName);
tline = '';
modTrace
fileID = fopen(outName,'w');
v = [(0:(numel(modTrace)-1)).' real(modTrace(:)) ].';
fprintf(fileID,'%d %e\n',v);
end
Instead of hardcoding the number 100, you could also use n=numel(dir('*EA.txt')). It count's the files ending with EA.txt
Related
This function reads the data from multiple mat files and save them in multiple txt files. But the data (each value) are saved one value in one column and so on. I want to save the data in a form of three columns (coordinates) in the text files, so each row has three values separated by space. Reshape the data before i save them in a text file doesn't work. I know that dlmwrite should be modified in away to make newline after three values but how?
mat = dir('*.mat');
for q = 1:length(mat)
load(mat(q).name);
[~, testName, ~] = fileparts(mat(q).name);
testVar = eval(testName);
pos(q,:,:) = testVar.Bodies.Positions(1,:,:);
%pos=reshape(pos,2,3,2000);
filename = sprintf('data%d.txt', q);
dlmwrite(filename , pos(q,:,:), 'delimiter','\t','newline','pc')
end
My data structure:
These data should be extracted from each mat file and stored in the corresponding text files like this:
332.68 42.76 42.663 3.0737
332.69 42.746 42.655 3.0739
332.69 42.75 42.665 3.074
A TheMathWorks-trainer once told me that there is almost never a good reason nor a need to use eval. Here's a snippet of code that should solve your writing problem using writematrix since dlmwrite is considered to be deprecated.
It further puts the file-handling/loading on a more resilient base. One can access structs dynamically with the .(FILENAME) notation. This is quite convenient if you know your fields. With who one can list variables in the workspace but also in .mat-files!
Have a look:
% path to folder
pFldr = pwd;
% get a list of all mat-files (returns an array of structs)
Lst = dir( fullfile(pFldr,'*.mat') );
% loop over files
for Fl = Lst.'
% create path to file
pFl = fullfile( Fl.folder, Fl.name );
% variable to load
[~, var2load, ~] = fileparts(Fl.name);
% get names of variables inside the file
varInfo = who('-file',pFl);
% check if it contains the desired variables
if ~all( ismember(var2load,varInfo) )
% display some kind of warning/info
disp(strcat("the file ",Fl.name," does not contain all required varibales and is therefore skipped."))
% skip / continue with loop
continue
end
% load | NO NEED TO USE eval()
Dat = load(pFl, var2load);
% DO WHATEVER YOU WANT TO DO
pos = squeeze( Dat.(var2load)(1,:,1:2000) );
% create file name for text file
pFl2save = fullfile( Fl.folder, strrep(Fl.name,'.mat','.txt') );
writematrix(pos,pFl2save,'Delimiter','\t')
end
To get your 3D-matrix data into a 2D matrix that you can write nicely to a file, use the function squeeze. It gets rid of empty dimensions (in your case, the first dimension) and squeezes the data into a lower-dimensional matrix
Why don't you use writematrix() function?
mat = dir('*.mat');
for q = 1:length(mat)
load(mat(q).name);
[~, testName, ~] = fileparts(mat(q).name);
testVar = eval(testName);
pos(q,:,:) = testVar(1,:,1:2000);
filename = sprintf('data%d.txt', q);
writematrix(pos(q,:,:),filename,'Delimiter','space');
end
More insight you can find here:
https://www.mathworks.com/help/matlab/ref/writematrix.html
I have a csv file that has complex numbers.
This is sample of some numbers I have in the csv file:
(0.12825663763789857+0.20327998150393212j),(0.21890748607218197+0.160563964013564j),(0.28205414129281525+0.09884068776334366j),(0.030927026479380615+0.26334550583848626j)
I want to read this file and then save in (.out) file all the real parts in the first column and all the imaginary parts in the second column (without the imaginary letter j).
Here is one attempt. It is slightly more complicated due to the ( and ) that surround your numbers.
First, use textscan to read the file. Since I guess you don't know how many numers are in the file, read everything into a singe string. Will work with mutiple lines, too:
filename = 'data.csv';
fid = fopen(filename);
content = textscan(fid, '%s');
fclose(fid);
For this purpose, content now is a slightly weird cell array (look at the textscan-docs for details). Just initialize the variable nums which will store the numbers and loop through content (if you know a bit more about your csv file, you might pre-allocate nums):
nums = [];
for c1 = 1:numel(content{1})
Next, split the string at every occurence of ,:
string_list = strsplit(content{1}{c1},',');
This gives another cell array. Loop through it to convert the strings to numbers (and end the outer loop):
for c2 = 1 : numel(string_list)
nums(end+1) = str2num(string_list{c2});
end
end
Last, just store the real and the imaginary part of the numbers in separate columns:
out = [];
out(:,1) = real(nums);
out(:,2) = imag(nums);
and save it to data.out.
Update As you mentioned precision, you could use
dlmwrite('data.out', out, 'precision','%.20f');
However, here you need to understand the floating point representation in Matlab. In particular, try to understand the following:
>> a = 0.12825663763789857
a =
0.1283
>> fprintf('%.20f\n', a)
0.12825663763789857397
>> eps(a)
ans =
2.7756e-17
Note that one could have done this without cenverting the strings to numbers, but the way above would allow you to use the data in Matlab instead of just saving it.
HEre is an attempt without converting your strings to numbers, therefore one does not have to deal with precision. It works with negative real and imaginary numbers, too. + signs are removed when written to the new file, - signs are preserved:
filename = 'data.csv';
fid = fopen(filename);
content = textscan(fid, '%s');
fclose(fid);
fid = fopen('data.out','w');
pattern = '(?<real>-{0,1}\d+.\d+)(?<imag>[+-]\d+.\d+)j';
for c1 = 1:numel(content{1})
result = regexp(content{1}{c1}, pattern, 'names');
for c2 = 1:numel(result)
fprintf(fid, '%s,%s\n', strrep(result(c2).real,'+',''), strrep(result(c2).imag,'+',''));
end
end
fclose(fid);
I have a large number of text files that I have to read, find the max value for a certain column, and the corresponding time. The for loop for finding these values works fine, but my problem is writing a text file that shows the three variables I need (thisfilename, M, and wavetime) for each iteration of the for loop.
Output_FileName_MaxWaveHeights = ['C:\Users\jl44459\Desktop\QGIS_and_Basement\BASEMENT\Mesh_5_2045\Run_A\','MaxWaveHeights.txt'];
writefile = fopen(Output_FileName_MaxWaveHeights,'a');
dinfo = dir('*.dat');
for K = 1 : length(dinfo)
thisfilename = dinfo(K).name; %just the name of the file
fileID = fopen(thisfilename); %creates numerical ID for the file name
thisdata = textscan(fileID,'%f64%f64%f64%f64%f64%f64%f64',500,'HeaderLines',1); %load just this file
thisdataM = cell2mat(thisdata); %transforms file from cell array to matrix
[M,I] = max(thisdataM(:,5)); %finds max WSE and row it's in
wavetime = 2*(I-1); %converts column of max WSE to time
fprintf(writefile,'%s %8.4f %4.0f \r\n',thisfilename,M,wavetime);
fclose(fileID); %closes file to make space for next one
end
The text file ends up just giving me the values for one iteration instead of all of them. I was able to use displaytable as a workaround, but then I have problems writing "thisfilename", which includes non-numerical characters.
Although I am not able to reproduce the issue with the code provided, a possible solution might be to write to the file outside of the loop and to close the file afterwards:
Output_FileName_MaxWaveHeights = ['C:\Users\jl44459\Desktop\QGIS_and_Basement\BASEMENT\Mesh_5_2045\Run_A\','MaxWaveHeights.txt'];
writefile = fopen(Output_FileName_MaxWaveHeights,'a');
s = [];
dinfo = dir('*.dat');
for K = 1 : length(dinfo)
thisfilename = dinfo(K).name; %just the name of the file
fileID = fopen(thisfilename); %creates numerical ID for the file name
thisdata = textscan(fileID,'%f64%f64%f64%f64%f64%f64%f64',500,'HeaderLines',1); %load just this file
thisdataM = cell2mat(thisdata); %transforms file from cell array to matrix
[M,I] = max(thisdataM(:,5)); %finds max WSE and row it's in
wavetime = 2*(I-1); %converts column of max WSE to time
s = [s, fprintf(writefile,'%s %8.4f %4.0f \r\n',thisfilename,M,wavetime)];
fclose(fileID); %closes file to make space for next one
end
fprintf(writefile,s);
fclose(writefile);
Solved--it was simply me forgetting to close the output file after the loop. Thanks for the help!
I ran a simulation which wrote a huge file to disk. The file is a big matrix v. I can't read it all, but I really only need a portion of the matrix, say, 1:100 of the columns and rows. I'd like to do something like
vtag = dlmread('v',1:100:end, 1:100:end);
Of course, that doesn't work. I know I should have only done the following when writing to the file
dlmwrite('vtag',v(1:100:end, 1:100:end));
But I did not, and running everything again would take two more days.
Thanks
Amir
Thankfully the dlmread function supports specifying a range to read as the third input. So if you wan to read all N columns for the first 100 rows, you can specify that with the following command
startRow = 1;
startColumn = 1;
endRow = 100;
endColumn = N;
rng = [startRow, startColumn, endRow, endColumn] - 1;
vtag = dlmread(filename, ',', rng);
EDIT Based on your clarification
Since you don't want 1:100 rows but rather 1:100:end rows, the following approach should work better for you.
You can use textscan to read chunks of data at a time. You can read a "good" row and then read in the next "chunk" of data to ignore (discarding it in the process), and continue until you reach the end of the file.
The code below is a slight modification of that idea, except it utilizes the HeaderLines input to textscan which instructs the function how many lines to ignore before reading in the data. The first time through the loop, no lines will be skipped, however all other times through the loop, rows2skip lines will be skipped. This allows us to "jump" through the file very rapidly without calling any additional file opertions.
startRow = 1;
rows2skip = 99;
columns = 3000;
fid = fopen(filename, 'rb');
% For now, we'll just assume you're reading in floating-point numbers
format = repmat('%f ', [1 columns]);
count = 1;
lines2discard = startRow - 1;
while ~feof(fid)
% Use "HeaderLines" to skip data before reading in data we care about
row = textscan(fid, format, 1, 'Delimiter', ',', 'HeaderLines', lines2discard);
data{count} = [row{:}];
% After the first time through, set the "HeaderLines" (i.e. lines to ignore)
% to be the # we want to skip between lines (much faster than alternatives!)
lines2discard = rows2skip;
count = count + 1;
end
fclose(fid);
data = cat(1, data{:});
You may need to adjust your format specifier for your own type of input.
I have a huge sparse matrix a and I want to save it in a .csv. I can not call full(a) because I do not have enough ram memory. So, calling dlmwrite with full(a) argument is not possible. We must note that dlmwrite is not working with sparse formatted matrices.
The .csv format is depicted below. Note that the first row and column with the characters should be included in the .csv file. The semicolon in the (0,0) position of the .csv file is necessary too.
;A;B;C;D;E
A;0;1.5;0;1;0
B;2;0;0;0;0
C;0;0;1;0;0
D;0;2.1;0;1;0
E;0;0;0;0;0
Could you please help me to tackle this problem and finally save the sparse matrix in the desired form?
You can use csvwrite function:
csvwrite('matrix.csv',a)
You could do this iteratively, as follows:
A = sprand(20,30000,.1);
delimiter = ';';
filename = 'filecontaininghugematrix.csv';
dims = size(A);
N = max(dims);
% create names first
idx = 1:26;
alphabet = dec2base(9+idx,36);
n = ceil(log(N)/log(26));
q = 26.^(1:n);
names = cell(sum(q),1);
p = 0;
for ii = 1:n
temp = repmat({idx},ii,1);
names(p+(1:q(ii))) = num2cell(alphabet(fliplr(combvec(temp{:})')),2);
p = p + q(ii);
end
names(N+1:end) = [];
% formats for writing
headStr = repmat(['%s' delimiter],1,dims(2));
headStr = [delimiter headStr(1:end-1) '\n'];
lineStr = repmat(['%f' delimiter],1,dims(2));
lineStr = ['%s' delimiter lineStr(1:end-1) '\n'];
fid = fopen(filename,'w');
% write header
header = names(1:dims(2));
fprintf(fid,headStr,header{:});
% write matrix rows
for ii = 1:dims(1)
row = full(A(ii,:));
fprintf(fid, lineStr, names{ii}, row);
end
fclose(fid);
The names cell array is quite memory demanding for this example. I have no time to fix that now, so think about this part yourself if it is really a problem ;) Hint: just write the header element wise, first A;, then B; and so on. For the rows, you can create a function that maps the index ii to the desired character, in which case the complete first part is not necessary.