I am currently trying to read in .csv files that can have different delimiters. At the moment I am using readtable but that only handles one type and the use of textscan isn't really viable as the file contains 50+ columns.
The main two types of delimiter are ';' and ','. I am also using uigetfile in order for the user to select the file.
So I am wondering how I would go about handling more than one type of delimiter? The delimiter is consistent throughout each file and they all contain the same number of columns (hence my use of readtable).
Any suggestions would be greatly appreciated.
Thanks in advance.
I'd recommend you to unify delimiters. Eg. replace all semicolons with commas or vice versa, like that
file = 'bad_delimiters.csv';
fd = fopen(file);
text = fscanf(fd,'%c');
semicolons = strfind(text,';');
text(semicolons) = ',';
fd = fopen('good_delimiters.csv', 'w');
fwrite(fd, text);
If you have MATLAB version R2016b or later you can specify multiple delimiters for readtable by defining a set of import options, as illustrated in this example. You will first create a detectImportOptions object, change the 'Delimiter' property to a cell array of characters, then pass these options to readtable:
opts = detectImportOptions('your_file.csv');
opts.Delimiter = {';', ','};
T = readtable('your_file.csv', opts);
Related
I have several tables in matlab that and I would like to write all to one .csv file, vertically concatenating. I would like to keep the column names from each table as the top row, and would like to use a loop to write the csv. The ultimate goal is to read the data in to R, but R.matlab did not work well. Suggestions about how to do this?
Alternatively how can I change filenames in a for loop using the iterator?
e.g. along the lines of
for i=1:10
writecsv('mydatai.csv',data(i))
end
So I must have at the end 10 csv files as output.
You can change the filename within the loop by using for sprintf string formatting function, for example:
dlmwrite(sprintf('mydata%i.csv', i), data(i) )
Note that the %i portion of the string is the sprintf formatting operator for an integer, it is just a coincidence that you also decided to name your iterator variable 'i'.
You can append extra data to an existing CSV by using the dlmwrite function, which uses a comma delimiter as the default, and including the '-append' flag.
Another way would be to use
writetable(Table,filename )
and to change file name after every alternation you can use
filename = ['mydata' num2str(i) '.csv']
I have a CSV file which I want to read in using matlab.
I've tried using csvread but it does not seem to recognize the semi-colon as the delimiter. Is there any other way?
R;W
100;0.1
200;0.5
300;0.9
You can use dlmread instead and specify the delimeter to be a semi-colon. You will also want to set the row offset to 1 so you skip the first non-numeric row.
data = dlmread('filename.csv', ';', 1);
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.
I'm trying to export a matrix f that is double. My data in f are real numbers in three columns. I want a txt file as an output with the columns separated by tabs. However, when I try the dlmwrite function, just the first column appears as output.
for k = 1:10
f = [idx', firsttime', sectime'];
filename = strcat(('/User/Detection_rerun/AF_TIMIT/1_state/mergedlabels_train/'),(files_train{k,1}),'.lab');
dlmwrite(filename,f,'\t') ;
end
When I use dlmwrite(filename,f,'\t','newline','pc') ; I keep getting an error Invalid attribute tag: \t . I even tried 'tab' instead of '\t' but a similar error appears. Please let me know if you have any suggestions. thank you
This is because you are not calling dlmwrite properly. To specify the delimiter, you must use the delimiter flag, followed by the specific delimiter you want. In your case, you use \t. In other words, you need to do this:
for k = 1:10
f = [idx', firsttime', sectime'];
filename = strcat(('/User/Detection_rerun/AF_TIMIT/1_state/mergedlabels_train/'),(files_train{k,1}),'.lab');
dlmwrite(filename,f,'delimiter','\t') ;
end
BTW, you are using the newline flag with pc, meaning that you are specifying carriage returns that are recognized by a PC. I suggest you leave this out and allow MATLAB to automatically infer this. Only force the newline characters if you know what you're doing.
FWIW, the MATLAB documentation is pretty clear about delimiters and other quirks about the function: http://www.mathworks.com/help/matlab/ref/dlmwrite.html
I am trying to import all double from a txt file, which has this form
#25x1 string
#9999x2 double
.
.
.
#(repeat ten times)
However, when I am trying to use import Wizard, only the first
25x1 string
9999x2 double.
was successfully loaded, the other 9 were simply ignored
How may I import all the data? (Does importdata has a maximum length or something?)
Thanks
It's nothing to do with maximum length, importdata is just not set up for the sort of data file you describe. From the help file:
For ASCII files and spreadsheets, importdata expects
to find numeric data in a rectangular form (that is, like a matrix).
Text headers can appear above or to the left of the numeric data,
as follows:
Column headers or file description text at the top of the file, above
the numeric data. Row headers to the left of the numeric data.
So what is happening is that the first section of your file, which does match the format importdata expects, is being read, and the rest ignored. Instead of importdata, you'll need to use textscan, in particular, this style:
C = textscan(fileID,formatSpec,N)
fileID is returned from fopen. formatspec tells textscan what to expect, and N how many times to repeat it. As long as fileID remains open, repeated calls to textscan continue to read the file from wherever the last read action stopped - rather than going back to the start of the file. So we can do this:
fileID = fopen('myfile.txt');
repeats = 10;
for n = 1:repeats
% read one string, 25 times
C{n,1} = textscan(fileID,'%s',25);
% read two floats, 9999 times
C{n,2} = textscan(fileID,'%f %f',9999);
end
You can then extract your numerical data out of the cell array (if you need it in one block you may want to try using 'CollectOutput',1 as an option).