I am trying to write a matrix into a text file using matlab. I used the code shown below
fName = 'Audio.txt';
fid = fopen('Audio.txt','w');
dlmwrite('Audio.txt', a, '\n');
but i am not getting all the values in single line.What I am expecting is one element in every line.How to make it happen
Related
I am appending to a csv file. The current code outputs a line: a;b;c;d
I need it to output a;b;c;d;
notice the extra ';' at the end of d. That is essential
matrix = [a,b,c,d]
dlmwrite('matrix.csv', matrix, 'delimiter',';','-append','roffset',0, 'precision',14)
any help would be appreciated.
I have had to keep variables a,b,c and d as numbers, or it makes it a character vector (or something) which makes my csv look funny
I've always had problems with the MatLab inbuild CSV writing methods. Why don't you code your own .CSV writing method?
Here, you could make a function something like:
function write_to_csv(filepath, matrix)
csv = fopen(filepath, 'a+'); % check what sort of open you'd like : https://uk.mathworks.com/help/matlab/ref/fopen.html#inputarg_permission
for ii = 1 : numel(matrix) % this loop depends on the dimensions of your matrix
fprintf(csv, '%s;', matrix(ii)); % check fprintf return type, depending on the data in the matrix : https://uk.mathworks.com/help/matlab/ref/fprintf.html?searchHighlight=fprintf&s_tid=doc_srchtitle#inputarg_formatSpec
end
fclose(csv);
end
This works for a 1D matrix you've supplied, run with:
write_to_csv('matrix.csv',matrix)
I need to read a txt dataset and do some analytics by matlab. the structure of the txt file is like this:
ID Genre AgeScale
1 M 20-26
2 F 18-25
So, I want to load this txt file and build a matrix. I was wondering if someone could help me with this. I used fopen function but it gives me a single array not a matrix with 3 columns.
MATLAB has an interactive data importer. Just type uiimport in the command window. It allows you to:
Name the variable based on heading as shown in your example. You can also manually change them.
Specify variable (column) type, e.g. numeric, cell array of strings, etc.
Auto generate an import script for next use (if desired)
If it works for you then congratulations, you don't need to waste hours to write an data import script :)
Function fopen only returns the file ID and not the content of the file. Once you open the file you use the file ID to read line by line and then parse each line with strsplit using space as the delimiter.
Here's one simple way of doing so:
fid = fopen('textfile.txt');
tline = fgetl(fid);
n = 1;
while ischar(tline)
data(n,:) = strsplit(tline(1:end-1),' ');
n=n+1;
tline = fgetl(fid);
end
fclose(fid);
Keep in mind that the matrix data is type string and not numeric, so if you want to use the numeric values of your dataset, you'll need to take a look at the functions str2num (str2double in newer versions) and strtok to split the AgeScale strings with delimiter '-'.
I have a very large matrix (M X N). I want to divide matrix into 10 equal parts (almost) and save each of them into a separate file say A1.txt, A2.txt, etc. or .mat format. How can I do this ?
Below is a code to divide a matrix into 10 equal parts and data_size is (M / 10).
for i=1:10
if i==1
data = DATA(1:data_size,:);
elseif i==10
data = DATA((i-1)*data_size+1:end,:);
else
data = DATA((i-1)*data_size+1: i*data_size,:);
end
save data(i).mat data
% What should I write here in order to save data into separate file data1.mat, data2.mat etc.
end
You said you wanted it in either txt format or mat format. I'll provide both solutions, and some of this is attributed to Daniel in his comment in your post above.
Saving as a text file
You can use fopen to open a file up for writing. This returns an ID to the file that you want to write to. After this, use fprintf and specify the ID to the file that you want to write to, and the data you want to write to this file. As such, with sprintf, generate the text file name you want, then use fprintf to write data to your file. It should be noted that writing matrices to fprintf in MATLAB assume column major format. If you don't want your data written this way and want it done in row-major, you need to transpose your data before you write this to file. I'll provide both methods in the code depending on what you want.
After you're done, use fclose to close the file noting that you have finished writing to it. Therefore, you would do this:
for i=1:10
if i==1
data = DATA(1:data_size,:);
elseif i==10
data = DATA((i-1)*data_size+1:end,:);
else
data = DATA((i-1)*data_size+1: i*data_size,:);
end
filename = sprintf('A%d.txt', i); %// Generate file name
fid = fopen(filename, 'w'); % // Open file for writing
fwrite(fid, '%f ', data.'); %// Write to file - Transpose for row major!
%// fwrite(fid, '%f ', data); %// Write to file - Column major!
fclose(fid); %// Close file
end
Take note that I space separated the numbers so you can open up the file and see how these values are written accordingly. I've also used the default precision and formatting by just using %f. You can play around with this by looking at the fprintf documentation and customizing the precision and leading zero formatting to your desire.
Saving to a MAT file
This is actually a more simpler approach. You would still use sprintf to save your data, then use the save command to save your workspace variables to file. Therefore, your loop would be this:
for i=1:10
if i==1
data = DATA(1:data_size,:);
elseif i==10
data = DATA((i-1)*data_size+1:end,:);
else
data = DATA((i-1)*data_size+1: i*data_size,:);
end
filename = sprintf('A%d.mat', i); %// Generate file name
save(filename, 'data');
end
Take note that the variable you want to save must be a string. This is why you have to put single quotes around the data variable as this is the variable you are writing to file.
You can use
save(['data' num2str(i) '.mat'], 'data');
where [ ] is used to concatenate strings and num2str to convert an integer to a string.
I am very much new to MATLAB.
I have two text file. One has two columns xy.txt (X AND Y coordinates). It has 80640 points.
The second has one column z.txt (z value according to the coordinate). The second text file is a result of a matlab program that I wrote. That program produces the z value for every 10 year time interval. I am modelling impact of sea-level rise during this century.
I want to make three column text file to plot contour maps.
I want to include that code to the main script I wrote so that I can get the contour map automatically.
I searched almost a day to find suitable answer but in vain
Thank you
This should give you what you want:
%Open and get the relevant data from the two files
fid1 = fopen('xy.txt');
fid2 = fopen('z.txt');
s1 = textscan(fid1,'%s %s','delimiter','\t');
s2 = textscan(fid2,'%s','delimiter','\t');
%close files
fclose(fid1);
fclose(fid2);
%sort data into an easy to use cell array
s=[s1{1,1},s1{1,2},s2{1,1}];
%Create new file and set permission to write
fid = fopen('xyz.txt','w');
%Loop through cell array s and write to file using a tab delimited format spec.
for ind = 1:size(s,1)
fprintf(fid,'%s\t%s\t%s\n',s{ind,:});
end
fclose(fid); %close file
This assumes that xy.txt and z.txt both have the same number of rows
I'm a Mac user (10.6.8) using MATLAB to process calculation results. I output large tables of numbers to .csv files. I then use the .csv files in EXCEL. This all works fine.
The problem is that each column of numbers needs a label (a string header). I can't figure out how to concatenate labels to the table of numbers. I would very much appreciate any advice. Here is some further information that might be useful:
My labels are contained within a cell array:
columnsHeader = cell(1,15)
that I fill in with calculation results; for example:
columnsHeader{1} = propertyStringOne (where propertyStringOne = 'Liq')
The sequence of labels is different for each calculation. My first attempt was to try and concatenate the labels directly:
labelledNumbersTable=cat(1,columnsHeader,numbersTable)
I received an error that concatenated types need to be the same. So I tried converting the labels/strings using cell2mat:
columnsHeader = cell2mat(columnsHeader);
labelledNumbersTable = cat(1,columnsHeader,numbersTable)
But that took ALL the separate labels and made them into one long word... Which leads to:
??? Error using ==> cat
CAT arguments dimensions are not consistent.
Does anyone know of an alternative method that would allow me to keep my original cell array of labels?
You will have to handle writing the column headers and the numeric data to the file in two different ways. Outputting your cell array of strings will have to be done using the FPRINTF function, as described in this documentation for exporting cell arrays to text files. You can then output your numeric data by appending it to the file (which already contains the column headers) using the function DLMWRITE. Here's an example:
fid = fopen('myfile.csv','w'); %# Open the file
fprintf(fid,'%s,',columnsHeader{1:end-1}); %# Write all but the last label
fprintf(fid,'%s\n',columnsHeader{end}); %# Write the last label and a newline
fclose(fid); %# Close the file
dlmwrite('myfile.csv',numbersTable,'-append'); %# Append your numeric data
The solution to the problem is already shown by others. I am sharing a slightly different solution that improves performance especially when trying to export large datasets as CSV files.
Instead of using DLMWRITE to write the numeric data (which internally uses a for-loop over each row of the matrix), you can directly call FPRINTF to write the whole thing at once. You can see a significant improvement if the data has many rows.
Example to illustrate the difference:
%# some random data with column headers
M = rand(100000,5); %# 100K rows, 5 cols
H = strtrim(cellstr( num2str((1:size(M,2))','Col%d') )); %'# headers
%# FPRINTF
tic
fid = fopen('a.csv','w');
fprintf(fid,'%s,',H{1:end-1});
fprintf(fid,'%s\n',H{end});
fprintf(fid, [repmat('%.5g,',1,size(M,2)-1) '%.5g\n'], M'); %'# default prec=5
fclose(fid);
toc
%# DLMWRITE
tic
fid = fopen('b.csv','w');
fprintf(fid,'%s,',H{1:end-1});
fprintf(fid,'%s\n',H{end});
fclose(fid);
dlmwrite('b.csv', M, '-append');
toc
The timings on my machine were as follows:
Elapsed time is 0.786070 seconds. %# FPRINTF
Elapsed time is 6.285136 seconds. %# DLMWRITE