Is there a way to append a file to an existing zip file/folder?
zip(zipfilename,filenames) would overwrite the original zipfilename.
I am using Windows 10 in case that makes a difference.
system(['powershell.exe -ExecutionPolicy Bypass Compress-Archive -update ',...
filename,' ',...
zipfilename]);
works.
Alternatively, as #Rotem pointed out, and in some situations more suitable, we can use Java's ZipOutputStream as long as we convert data to binary first.
If we start with a file test.csv, then the contained string can be read into an uint8 array by
filename = 'test.csv'; % change filename as needed.
fid = fopen(filename, 'r');
data = fread(fid , '*uint8');
fclose(fid );
If we start with data in a Matlab Workspace, we need to convert the data into the format we desire in the eventual output file and then convert it to binary. For example, if the desired compressed file is a .csv file, in other words, formatted text, we can prepare the string output with sprintf and convert it to the corresponding uint8 array such as
data = uint8(sprintf('%d, %d\r\n', [1,2;3,4]));
Following the above, one can use Java's ZipOutputStream to output to an existing zip file. Example below.
filename='test.csv'; % change filename of zip entry as needed
zipfilename='test.zip'; % change filename as needed
fos = java.io.FileOutputStream(zipfilename);
zos = java.util.zip.ZipOutputStream(fos);
ze = java.util.zip.ZipEntry(filename);
% zos.setLevel(9); % optional
zos.putNextEntry(ze);
zos.write(data, 0, numel(data));
zos.finish;
zos.close;
The benefit of this approach is that, if the data starts off in the current Matlab Worksapce, no additional file needs to be created, which would have required additional i/o use 3 times (in the above example, write test.csv, read csv, delete csv).
Another benefit is that the this method does not require powershell which is OS dependent -- not available in earlier Windows versions for example.
If the data starts off in an external file with Windows 10, as specified in the OP, then the 1st method is more expedient.
Note: Additional information on reading from the zip file or reading file list from zip file can be found here and here.
Related
My matlab function is in a folder that contains the main project and the other functions of the code. However, the data is stored in a folder withing the main one named "data" and inside the specific dataset that i want, for example "ded4" in this example. I can't figure out how to open the text file that I want without changing the file to the main folder. The code I have so far is:
function[Classify] = Classify(logDir)
%%%%logDir='ded014a04';
Directory = ['data/' logDir '/']
Filename = [logDir '-fixationsOffSet']
File_name = fullfile(Directory,Filename)
File = fopen(File_name,'r')
end
The code is in the 'dev' folder, I think my path is correct because when I do
open(File_name)
it opens.
Thanks for the help
If you want to open the file in the editor, use
open(File_name)
If you want to read data from the file, you can use
dlmread(File_name) % Read ASCII delimited file.
or
C = textscan(File,'FORMAT') % Read formatted data from text file or string.
or more low-level using fscanf, e.g., if the file contains three columns of integers you do the following: Read the values in column order, and transpose to match the appearance of the file: (from the help of fprintf)
fid = fopen('count.dat');
A = fscanf(fid,'%d',[3,inf])';
fclose(fid);
I am creating a matlab application that is analyzing data on a daily basis.
The data is read in from an csv file using xlsread()
[num, weather, raw]=xlsread('weather.xlsx');
% weather.xlsx is a spreadsheet that holds a list of other files (csv) i
% want to process
for i = 1:length(weather)
fn = [char(weather(i)) '.csv'];
% now read in the weather file, get data from the local weather files
fnOpen = xlsread(fn);
% now process the file to save out the .mat file with the location name
% for example, one file is dallasTX, so I would like that file to be
% saved as dallasTx.mat
% the next is denverCO, and so denverCO.mat, and so on.
% but if I try...
fnSave=[char(weather(i)) '.mat'] ;
save(fnSave, fnOpen) % this doesn't work
% I will be doing quite a bit of processing of the data in another
% application that will open each individual .mat file
end
++++++++++++++
Sorry about not providing the full information.
The error I get when I do the above is:
Error using save
Argument must contain a string.
And Xiangru and Wolfie, the save(fnSave, 'fnOpen') works as you suggested it would. Now I have a dallasTX.mat file, and the variable name inside is fnOpen. I can work with this now.
Thanks for the quick response.
It would be helpful if you provide the error message when it doesn't work.
For this case, I think the problem is the syntax for save. You will need to do:
save(fnSave, 'fnOpen'); % note the quotes
Also, you may use weather{i} instead of char(weather(i)).
From the documentation, when using the command
save(filename, variables)
variables should be as described:
Names of variables to save, specified as one or more character vectors or strings. When using the command form of save, you do not need to enclose the input in single or double quotes. variables can be in one of the following forms.
This means you should use
save(fnSave, 'fnOpen');
Since you want to also use a file name stored in a variable, command syntax isn't ideal as you'd have to use eval. In this case the alternative option would be
eval(['save ', fnSave, ' fnOpen']);
If you had a fixed file name (for future reference), this would be simpler
save C:/User/Docs/MyFile.mat fnOpen
I want to read multiple files from a folder but this code does not work properly:
direction=dir('data');
for i=3:length(direction)
Fold_name=strcat('data\',direction(i).name);
filename = fullfile(Fold_name);
fileid= fopen(filename);
data = fread (fileid)';
end
I modified your algorithm to make it easier
Just use this form :
folder='address\datafolder\' ( provide your folder address where data is located)
then:
filenames=dir([folder,'*.txt']); ( whatever your data format is, you can specify it in case you have other files you do not want to import, in this example, i used .txt format files)
for k = 1 : numel(filenames)
Do your code
end
It should work. It's a much more efficient method, as it can apply to any folder without you worrying about names, number order etc... Unless you want to specify certain files with the same format within the folder. I would recommend you to use a separate folder to put your files in.
In case of getting access to all the files after reading:
direction=dir('data');
for i=3:length(direction)
Fold_name=strcat('data\',direction(i).name);
filename = fullfile(Fold_name);
fileid(i)= fopen(filename);
data{i-2} = fread (fileid(i))';
end
I have multiple arrays with string data. All of them should be exported into a .csv file. The file should be saved in a subfolder. The file name is variable.
I used the code as follows:
fpath = ('./Subfolder/');
m_date = inputdlg('Date of measurement [yyyymmdd_exp]');
m_name = inputdlg('Characteristic name of the expteriment');
fformat = ('.csv');
fullstring = strcat(fpath, m_date,'_', m_name, fformat);
dlmwrite(fullstring,measurement);
However, I get an error that FILE must be a filename string or numeric FID
What's the reason?
Best
Andreas
What you are asking to do is fairly straightforward for Matlab or Octave. The first part is creating a file with a filename that changes. the best way to do this is by concatenating the strings to build the one you want.
You can use: fullstring = strcat('string1','string2')
Or specifically: filenameandpath = strcat('./Subfolder/FixedFileName_',fname)
note that because strings are pretty much just character arrays, you can also just use:
fullstring = ['string1','string2']
now, if you want to create CSV data, you'll first have to read in the file, possibly parse the data in some way, then save it. As Andy mentioned above you may just be able to use dlmwrite to create the output file. We'll need to see a sample of the string data to have an idea whether any more work would need to be done before dlmwrite could handle it.
Via textscan, I am reading a number of .txt files:
fid1 = fopen('Ev_An_OM2_l5_5000.txt','r');
This is a simplification as in reality I am loading several hundred .txt files via:
files = dir('Ev_An*.txt');
Important information not present within the .txt files themselves are instead part of the filename.
Is there a way to concisely extract portions of the filename and save them as strings/numbers? For example saving 'OM2' and '5000' from the above filename as variables.
fileparts appears to require the full path of the file rather than just defaulting to the MATLAB folder as with textscan.
It depends on how fixed your filename is. If your filename is in the string filename, then you can use regexp to extract parts of your filename, like so:
filename = 'Ev_An_OM2_l5_5000.txt'; %or whatever
parts = regexp(filename,'[^_]+_[^_]+_([^_]+)_[^_]+_([^\.]+)\.txt','tokens');
This will give you parts{1}=='OM2' and parts{2}=='5000', assuming that your filename is always in the form of
something_something_somethingofinterest_something_somethingofinterest.txt
Update:
If you like structs more than cells, then you can name your tokens like so:
parts = regexp(filename,'[^_]+_[^_]+_(?<first>[^_]+)_[^_]+_(?<second>[^\.]+)\.txt','names');
in which case parts.first=='OM2' and parts.second=='5000'. You can obviously name your tokens according to their actual meaning, since they are important. You just have to change first and second accordingly in the code above.
Update2:
If you use dir to get your filenames, you should have a struct array with loads of unnecessary information. If you really just need the file names, I'd use a for loop like so:
files = dir('Ev_An*.txt');
for i=1:length(files)
filename=files(i).name;
parts = regexp(filename,'[^_]+_[^_]+_(?<first>[^_]+)_[^_]+_(?<second>[^\.]+)\.txt','tokens');
%here do what you want with parts.first, parts.second and the file itself
end