I have a folder full of xls files, named data_00001 through data_10000. Each file has a dozen or so identically named tabs full of RV's. I am interested in reading all files and tabs and creating histograms of the RV's.
Is there a way to read in the last 5 digits of the file names and attached them to each tab name (which I saved as a variable)?
I used regexp to extract the number as a string and converted it to a double, and I used a for loop to save variable X{1,k}. How can I incorporate the saved double into this variable?
Are you looking for something like this?
filenames = ['data_00001','data_10000'];
nums = regexp(filenames, '[0-9]+', 'match');
tag = 'TAG';
for i=1:size(nums,2)
eval(['A_' tag '_' sprintf("%s",nums{1,i}) ' = zeros(1)']);
end
It creates matrices (zero in this case) with variable names
A_TAG_00001 = 0
A_TAG_10000 = 0
Related
this question about matlab:
i'm running a loop and each iteration a new set of data is produced, and I want it to be saved in a new file each time. I also overwrite old files by changing the name. Looks like this:
name_each_iter = strrep(some_source,'.string.mat','string_new.(j).mat')
and what I#m struggling here is the iteration so that I obtain files:
...string_new.1.mat
...string_new.2.mat
etc.
I was trying with various combination of () [] {} as well as 'string_new.'j'.mat' (which gave syntax error)
How can it be done?
Strings are just vectors of characters. So if you want to iteratively create filenames here's an example of how you would do it:
for j = 1:10,
filename = ['string_new.' num2str(j) '.mat'];
disp(filename)
end
The above code will create the following output:
string_new.1.mat
string_new.2.mat
string_new.3.mat
string_new.4.mat
string_new.5.mat
string_new.6.mat
string_new.7.mat
string_new.8.mat
string_new.9.mat
string_new.10.mat
You could also generate all file names in advance using NUM2STR:
>> filenames = cellstr(num2str((1:10)','string_new.%02d.mat'))
filenames =
'string_new.01.mat'
'string_new.02.mat'
'string_new.03.mat'
'string_new.04.mat'
'string_new.05.mat'
'string_new.06.mat'
'string_new.07.mat'
'string_new.08.mat'
'string_new.09.mat'
'string_new.10.mat'
Now access the cell array contents as filenames{i} in each iteration
sprintf is very useful for this:
for ii=5:12
filename = sprintf('data_%02d.mat',ii)
end
this assigns the following strings to filename:
data_05.mat
data_06.mat
data_07.mat
data_08.mat
data_09.mat
data_10.mat
data_11.mat
data_12.mat
notice the zero padding. sprintf in general is useful if you want parameterized formatted strings.
For creating a name based of an already existing file, you can use regexp to detect the '_new.(number).mat' and change the string depending on what regexp finds:
original_filename = 'data.string.mat';
im = regexp(original_filename,'_new.\d+.mat')
if isempty(im) % original file, no _new.(j) detected
newname = [original_filename(1:end-4) '_new.1.mat'];
else
num = str2double(original_filename(im(end)+5:end-4));
newname = sprintf('%s_new.%d.mat',original_filename(1:im(end)-1),num+1);
end
This does exactly that, and produces:
data.string_new.1.mat
data.string_new.2.mat
data.string_new.3.mat
...
data.string_new.9.mat
data.string_new.10.mat
data.string_new.11.mat
when iterating the above function, starting with 'data.string.mat'
I have a folder containing a series of data with file names like this:
abc1
abc2
abc3
bca1
bca2
bca3
bca4
bca5
cba1
... etc
My goal is to load all the relevant files for each file name, so all the "abc" files, and plot them in one graph. Then move on to the next file name, and do the same, and so forth. Is there a way to do this?
This is what I currently have to load and run through all the files, grab the data in them and get their name (without the .mat extension) to be able to save the graph with the same filename.
dirName = 'C:\DataDirectory';
files = dir( fullfile(dirName,'*.mat') );
files = {files.name}';
data = cell(numel(files),1);
for i=1:numel(files)
fname = fullfile(dirName,files{i});
disp(fname);
files{i} = files{i}(1:length(files{i})-4);
disp(files{i});
[Rest of script]
end
You already found out about the cool features of dir, and have a cell array files, which contains all file names, e.g.
files =
'37abc1.mat'
'37abc2.mat'
'50bca1.mat'
'50bca2.mat'
'1cba1.mat'
'1cba2.mat'
The main task now is to find all prefixes, 37abc, 50bca, 1cba, ... which are present in files. This can be done using a regular expression (regexp). The Regexp Pattern can look like this:
'([\d]*[\D]*)[\d]*.mat'
i.e. take any number of numbers ([\d]*), then any number of non-numeric characters ([\D]*) and keep those (by putting that in brackets). Next, there will be any number of numeric characters ([\d]*), followed by the text .mat.
We call the regexp function with that pattern:
pre = regexp(files,'([\d]*[\D]*)[\d]*.mat','tokens');
resulting in a cell array (one cell for each entry in files), where each cell contains another cell array with the prefix of that file. To convert this to a simple not-nested cell array, we call
pre = [pre{:}];
pre = [pre{:}];
resulting in
pre =
'37abc' '37abc' '50bca' '50bca' '1cba' '1cba'
To remove duplicate entries, we use the unique function:
pre = unique(pre);
pre =
'37abc' '50bca' '1cba'
which leaves us with all prefixes, that are present. Now you can loop through each of these prefixes and apply your stuff. Everything put together is:
% Find all files
dirName = 'C:\DataDirectory';
files = dir( fullfile(dirName,'*.mat') );
files = {files.name}';
% Find unique prefixes
pre = regexp(files,'([\d]*[\D]*)[\d]*.mat','tokens');
pre = [pre{:}]; pre = [pre{:}];
pre = unique(pre);
% Loop through prefixes
for ii=1:numel(pre)
% Get files with this prefix
curFiles = dir(fullfile(dirName,[pre{ii},'*.mat']));
curFiles = {curFiles.name}';
% Loop through all files with this prefix
for jj=1:numel(curFiles)
% Here the magic happens
end
end
Sorry, I misunderstood your question, I found this solution:
file = dir('*.mat')
matching = regexp({file.name}, '^[a-zA-Z_]+[0-9]+\.mat$', 'match', 'once'); %// Match once on file name, must be a series of A-Z a-z chars followed by numbers.
matching = matching(~cellfun('isempty', matching));
str = unique(regexp(matching, '^[a-zA-Z_]*', 'match', 'once'));
str = str(~cellfun('isempty', str));
group = cell(size(str));
for is = 1:length(str)
ismatch = strncmp(str{is}, matching, length(str{is}));
group{is} = matching(ismatch);
end
Answer came from this source: Matlab Central
I have a .txt file with rows consisting of three elements, a word and two numbers, separated by commas.
For example:
a,142,5
aa,3,0
abb,5,0
ability,3,0
about,2,0
I want to read the file and put the words in one variable, the first numbers in another, and the second numbers in another but I am having trouble with textscan.
This is what I have so far:
File = [LOCAL_DIR 'filetoread.txt'];
FID_File = fopen(File,'r');
[words,var1,var2] = textscan(File,'%s %f %f','Delimiter',',');
fclose(FID_File);
I can't seem to figure out how to use a delimiter with textscan.
horchler is indeed correct. You first need to open up the file with fopen which provides a file ID / pointer to the actual file. You'd then use this with textscan. Also, you really only need one output variable because each "column" will be placed as a separate column in a cell array once you use textscan. You also need to specify the delimiter to be the , character because that's what is being used to separate between columns. This is done by using the Delimiter option in textscan and you specify the , character as the delimiter character. You'd then close the file after you're done using fclose.
As such, you just do this:
File = [LOCAL_DIR 'filetoread.txt'];
f = fopen(File, 'r');
C = textscan(f, '%s%f%f', 'Delimiter', ',');
fclose(f);
Take note that the formatting string has no spaces because the delimiter flag will take care of that work. Don't add any spaces. C will contain a cell array of columns. Now if you want to split up the columns into separate variables, just access the right cells:
names = C{1};
num1 = C{2};
num2 = C{3};
These are what the variables look like now by putting the text you provided in your post to a file called filetoread.txt:
>> names
names =
'a'
'aa'
'abb'
'ability'
'about'
>> num1
num1 =
142
3
5
3
2
>> num2
num2 =
5
0
0
0
0
Take note that names is a cell array of names, so accessing the right name is done by simply doing n = names{ii}; where ii is the name you want to access. You'd access the values in the other two variables using the normal indexing notation (i.e. n = num1(ii); or n = num2(ii);).
I am trying to append filenames in a directory to a list for later processing. The code below does not work.
files = dir( fullfile(home,'*.csv') );
files = {files.name}'; %'# file names
symbolsList = [];
filedata = cell(numel(files),1); %# store file contents
for i=1:numel(files)
[pathstr,name,ext] = fileparts(files{i});
symbolsList(end + 1) = name; % THIS GIVES ERROR
end
In your code, symbolsList will be interpreted as an array of characters. The statement where the error is appearing is interpreted as appending a single character to symbolsList. You are probably getting a subscript alignment mismatch because a name will most likely have more than one character, yet you are trying to fit many characters into a single spot in that array of characters. That's probably not what you want.
You want each "space" to have a name. Because each name will most likely not have the same amount of characters, you should probably use a cell array instead:
files = dir( fullfile(home,'*.csv') );
files = {files.name}'; %'# file names
symbolsList = cell(numel(files),1); %// Change
filedata = cell(numel(files),1); %# store file contents
for i=1:numel(files)
[pathstr,name,ext] = fileparts(files{i});
symbolsList{i} = name; %// Change
end
Take note that I've pre-allocated the cell array and for each file you want to look at, I've indexed into the right cell and placed the name there. This is preferred over concatenation primarily due to efficiency. To access the ith name, simply do:
name_to_choose = symbolsList{i};
Minor Note
filedata in your code isn't being used anywhere at all. Are you sure you put all of your code up?
I have a large text file (~3500 lines) which contains output data from an instrument. This consists of repeated entries from different measurements which are all formatted as follows:
* LogFrame Start *
variablename1: value
variablename2: value
...
variablename35: value
* LogFrame End *
Each logframe contains 35 variables. From these I would like to extract two, 'VName' and 'EMGMARKER' and put the associated values in columns in a matlab array, (i.e. the array should be (VName,EMGMARKER) which I can then associate with data from another output file which I already have in a matlab array. I have no idea where to start with this in order to extract the variables from this file, so hence my searches on the internet so far have been unsuccessful. Any advice on this would be much appreciated.
You could use textscan:
C = textscan(file_id,'%s %f');
Then you extract the variables of interest like this:
VName_indices = strcmp(C{1},'VName:');
VName = C{2}(VName_indices);
If the variable names, so 'VName' and 'EMGMARKER' , are always the same you can just read through the file and search for lines containing them and extract data from there. I don't know what values they contain so you might have to use cells instead of arrays when extracting them.
fileID = fopen([target_path fname]); % open .txt file
% read the first line of the specified .txt file
current_line = fgetl(fileID);
counter = 1;
% go through the whole file
while(ischar(current_line))
if ~isempty(strfind(current_line, VName))
% now you find the location of the white space delimiter between name and value
d_loc = strfind(current_line,char(9));% if it's tab separated - so \t
d_loc = strfind(current_line,' ');% if it's a simple white space
variable_name{counter} = strtok(current_line);% strtok returns everything up until the first white space
variable_value{counter} = str2double(strtok(current_line(d_loc(1):end)));% returns everything form first to second white space and converts it into a double
end
% same block for EMGMARKER
counter = counter+1;
current_line = fgetl(fileID);% next line
end
You do the same for EMGMARKER and you have cells containing the data you need.