I have a question about outputting some results to a text file in MATLAB. Essentially I have read in data from 50000 files (numbered sequentially from 1 to 50000) and I have plotted it. Only those files which meet a certain condition are plotted. I now want to add some code which will allow me to write text to a data file. The specific text I want to write is the file numbers (from 1 to 50000) which meet the certain condtions and have been plotted.
When I try and do this the plots work fine but the text file only contains the last file number. For example if the last file number to fulfil the conditions to be plotted is 50000, then the text file only contains 50000. I am unsure how to change the code - any help/advice/tips would be appreciated.
start_sim=1;
end_sim=50000;
h = zeros (1,10000);
for i=start_sim:end_sim
a=int2str(i);
File =strcat('result_', 'simulation', '_', a, 'I_byCal_totale.out');
est_tot=importdata(File, '\t', 1);
cal_tot=est_tot.data;
magnitude=1;
t1=cal_tot(:,1)+1750;
model=cal_tot(:,3)+cal_tot(:,5);
if (model(211)>=25)
if (model(211)<=150)
h(a)=plot(t1,model);
xlim([1910 1970]);
ylim([0 500]);
hold all
clickableLegend(h(a),a,'Location','BestOutside')
%Generate OutputFile
fid = fopen('Modeloutputs.in','w+');
%Generate some text to write in the file (e.g. the simulation number)
% Print the text in the file
fprintf(fid,h(a),'\t','\n');
%close the file
fclose(fid);
end
fid = fopen('Modeloutputs.in','a+');
should do your job. Your initial attempt using 'w+' will
Delete the contents of an existing
file or create new file, and open it
for reading and writing.
as the documentation says. Another option is to move fopen & fclose outside of your loop which I would favor.
Related
I am trying to load a file in Matlab. But I am a bit confused about the best way to do it.
The file has 3 columns and looks like the screenshot below:
This file I can load very quickly by doing load('c').
However, I had to add 2 NaNs on the bottom row.
The original file actually looks like the file below:
Now if I do load('c') on the file below I get the error:
Error using load
Unable to read file 'c'. Input must be a MAT-file or an ASCII file containing numeric
data with same number of columns in each row.
Of course I can use ImportData to import this file, but it is just soooo slow to import it.
Any suggestions?
You should be able to use c = readtable('c'). This should automatically change the empty entries to "NaN" by default, but if not, there is a way to set that in the options.
If I have a file that is tricky to import (prior to readtable()...that made things a lot easier in the last few years), I will often use the Import Data tool (if its a really big file you can make a mock-up of the complicated file so it loads faster) then change all the import settings as I would want it, then where the green check says "Import Selection" use the black drop down arrow to select "Generate Function." This will give you the coded way of setting everything up to get the file in just the way you want it.
load() is better suited for reading in previously saved '.mat' files that were created in Matlab.
Here's a low-level approach, which might be faster than other methods:
filename = 'c'; % name of the file
N = 3; % number of columns
fid = fopen(filename, 'r'); % open file for reading
x = fscanf(fid, '%f'); % read all values as a column vector
fclose(fid); % close file
x = [x; NaN(N-mod(numel(x)-1,N)-1, 1)]; % include NaN's to make length a multiple of N
x = reshape(x, N, []).'; % reshape to N columns in row-major order
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 have a routine that opens a lookup table file to see if a certain entry already exists before writing to the file. Each line contains about 2,500 columns of data. I need to check the first 2 columns of each line to make sure the entry doesn't exist.
I don't want to have to read in 2,500 columns for every line just to check 2 entries. I was attempting to use the fscanf function, but it gives me an Invalid size error when I attempt to only read 2 columns. Is there a way to only read part of each line of an input file?
if(exist(strcat(fileDirectory,fileName),'file'))
fileID = fopen(strcat(fileDirectory,fileName),'r');
if(fileID == -1)
disp('ERROR: Could not open file.\n')
end
% Read file to see if line already exists
dataCheck = fscanf(fileID, '%f %f', [inf 2]);
for i=1:length(dataCheck(:,1))
if(dataCheck(i,1) == sawAnglesDeg(sawCount))
if(dataCheck(i,2) == sarjAnglesDeg(floor((sawCount-1)/4)+1))
% This line has already been written in lookup table
lineExists = true;
disp('Duplicate lookup table line found. Skipping...\n')
break;
end
end
end
fclose(fileID);
end
Well, not really.
You should be able in a loop to do an fscanf of the first two doubles, followed by a fgetl to read the rest of the line, i.e. on the form:
while there_are_more_lines
dataCheck = fscanf(fileID, '%f', 2);
fgetl(fileID); % Read remainder of line, discarding it
% Do check here for each line
end
Since it is a text file, you can not really skip reading characters from the file. For binary files you can do an fseek, which can jump round in the file based on a byte-count - it can be used if you know exactly where the next line starts (in byte-count). But for a text file you do not know that, since each line will vary in length. If you save the data in a binary file instead, it would be possible to do something like that.
What I would probably do: Create two files, the first one containing the two "check-values", that could be read in quickly, and the other one containing the 2500 columns of data, with or without the two "check-values". They should be updated synchronously; when adding one line to the first file, also one line is added to the second file.
And I would definitely make a checkData matrix variable and keep that in memory as long as possible; when adding a new line to the file, also update the checkData matrix, so you should only need to read the file once initially and use the checkData matrix for the rest of the life of your program.
With textscan you can skip fields, parts of fields, or even "rest of line", so I would do this (based on MATLAB help example slightly modified):
fileID = fopen('data.dat');
data = textscan(fileID,'%f %f %*[^\n]');
fclose(fileID);
Then check data (should be the two columns you want) to see if any of those rows matches the requirements.
As #Jesper Grooss wrote, there is no solution to skip the remaining of a line without reading it. In a single text file context, a fastest solution would probably consist of
reading the entire file with textscan (one line of text into one cell element of a matrix)
appending the new line to the matrix even if it is a duplicate entry
uniquing the cell matrix with unique(cellmatrix, 'rows')
appending the new line to the text file if it corresponds to a new entry
The uniquing step replaces the putatively costly for loop.
My raw CSV file looks like the 1st pic. And I wants to use Matlab read it into the format as the 2rd pic. I have over 1000 the same kind of CSV files, it will be painful if I do it by copy/paste. How can I do this? Any examples?
raw data:
output data:
First thing to realize is that a .csv file has a very simple format. Your above file is actually a plain text file with the following text on each line:
id,A001
height
a1,a2,a3
3,4,5
3,4,5
6,7,5
weight
a1,a2,a3
4,4,5
5,4,6
i6,7,5
So it is not all that hard for you to write your own parser in Matlab. You want to use commands like
fid = fopen('filename.csv','r');
L = fgetl(fid); % get a text line from the file
commas = find(L==','); % find where the commas are in the line
n1 = str2num(L(1:commas(1)-1); % convert the first comma-delimited number on line L
fidout - fopen('myfile.csv','w');
Lout = [ L(commas(2)+1:commas(3)-1) ', a1, a1'];
fwrite(fidout,Lout); % write a line out to the output file
fclose all; % close all open files.
It will seem slow at first reading the various values in to various variables, and then arranging them to write out the way you want them written out to your output file. But once you get rolling it will go pretty fast and you will find yourself with a pretty good understanding of what is in files, and you will know first hand what is involved in writing something like texscan.m or csvwrite.m and so on.
Good luck!