This question already has answers here:
How can I concatenate strings in a cell array with spaces between them in MATLAB?
(5 answers)
Closed 9 years ago.
I have a variable which is the list of string of a listBox handle
string = get(handles.ListBox,'string');
string=
'file1'
'file2'
I want to create a single string like:
line= 'file1 file2'
In order to write it in one line in my output file. The number of input files may vary in every case so I would like to do it in a general way. I have tried 'horzcat', 'strcat' but no success.
There is a strjoin function specifically for this task:
C = {'one', 'two', 'three'};
str = strjoin(C)
The simplest way, and IMHO cleanest way, is to make a "matrix" out of them:
s1 = 'bla';
s2 = 'blabla';
scat = [ s1, s2 ];
I found a nice way:
S = {'file1'; 'file2'};
strjoin(S(:)', ' ')
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 string and I need two characters to be returned.
I tried with strsplit but the delimiter must be a string and I don't have any delimiters in my string. Instead, I always want to get the second number in my string. The number is always 2 digits.
Example: 001a02.jpg I use the fileparts function to delete the extension of the image (jpg), so I get this string: 001a02
The expected return value is 02
Another example: 001A43a . Return values: 43
Another one: 002A12. Return values: 12
All the filenames are in a matrix 1002x1. Maybe I can use textscan but in the second example, it gives "43a" as a result.
(Just so this question doesn't remain unanswered, here's a possible approach: )
One way to go about this uses splitting with regular expressions (MATLAB's strsplit which you mentioned):
str = '001a02.jpg';
C = strsplit(str,'[a-zA-Z.]','DelimiterType','RegularExpression');
Results in:
C =
'001' '02' ''
In older versions of MATLAB, before strsplit was introduced, similar functionality was achieved using regexp(...,'split').
If you want to learn more about regular expressions (abbreviated as "regex" or "regexp"), there are many online resources (JGI..)
In your case, if you only need to take the 5th and 6th characters from the string you could use:
D = str(5:6);
... and if you want to convert those into numbers you could use:
E = str2double(str(5:6));
If your number is always at a certain position in the string, you can simply index this position.
In the examples you gave, the number is always the 5th and 6th characters in the string.
filename = '002A12';
num = str2num(filename(5:6));
Otherwise, if the formating is more complex, you may want to use a regular expression. There is a similar question matlab - extracting numbers from (odd) string. Modifying the code found there you can do the following
all_num = regexp(filename, '\d+', 'match'); %Find all numbers in the filename
num = str2num(all_num{2}) %Convert second number from str
I have file names stored as follows:
>> allFiles.name
ans =
k-120_knt-500_threshold-0.3_percent-34.57.csv
ans =
k-216_knt-22625_threshold-0.3_percent-33.33.csv
I wish to extract the 4 values from them and store in a cell.
data={};
for k =1:numel(allFiles)
data{k,1}=csvread(allFiles(k).name,1,0);
data{k,2}= %kvalue
data{k,3}= %kntvalue
data{k,4}=%threshold
data{k,5}=%percent
...
end
There's probably a regular expression that can be used to do this, but a simple piece of code would be
data={numel(allFiles),5};
for k =1:numel(allFiles)
data{k,1}=csvread(allFiles(k).name,1,0);
[~,name] = fileparts(allFiles(k).name);
dashIdx = strfind(name,'-'); % find location of dashes
usIdx = strfind(name,'_'); % find location of underscores
data{k,2}= str2double(name(dashIdx(1)+1:usIdx(1)-1)); %kvalue
data{k,3}= str2double(name(dashIdx(2)+1:usIdx(2)-1)); %kntvalue
data{k,4}= str2double(name(dashIdx(3)+1:usIdx(3)-1)); %threshold
data{k,5}= str2double(name(dashIdx(4)+1:end)); %percent
...
end
For efficiency, you might consider using a single matrix to store all the numeric data, and/or a structure (so that you can access the data by name rather than index).
You simply need to tokenize using strtok multiple times (there is more than 1 way to solve this). Someone has a handy matlab script somewhere on the web to tokenize strings into a cell array.
(1) Starting with:
filename = 'k-216_knt-22625_threshold-0.3_percent-33.33.csv'
Use strfind to prune out the extension
r = strfind(filename, '.csv')
filenameWithoutExtension = filename(1:r-1)
This leaves us with:
'k-216_knt-22625_threshold-0.3_percent-33.33'
(2) Then tokenize this:
'k-216_knt-22625_threshold-0.3_percent-33.33'
using '_' . You get the tokens:
'k-216'
'knt-22625'
'threshold-0.3'
'percent-33.33'
(3) Lastly, for each string, tokenize using using '-'. Each second string will be:
'216'
'22625'
'0.3'
'33.33'
And use str2num to convert.
Strategy: strsplit() + str2num().
data={};
for k =1:numel(allFiles)
data{k,1}=csvread(allFiles(k).name,1,0);
words = strsplit( allFiles(k).name(1:(end-4)), '_' );
data{k,2} = str2num(words{1}(2:end));
data{k,3} = str2num(words{2}(4:end));
data{k,4} = str2num(words{3}(10:end));
data{k,5} = str2num(words{4}(8:end));
end
This question already has an answer here:
Closed 10 years ago.
Possible Duplicate:
Using regexp to find a word
I'm working on an assignment for my CS course.
We're given a plain text file, which, in my case, contains a series of tweets.
What I need to do is create a script that will detect hashtags, and then save each hashtag into an cell array.
So far I know how to write a function that detects the '#' symbol...
strfind(textRead{i},'#');
where in a for loop where i=1:30 (that is, the number of cells of text). However, past that, I'm at a loss as to how I should write a script that will detect the '#' and return the text between that and the next ' ' (space) character.
Try this:
str = '#someHashtag other tweet text ignore #random';
regexp(str, '#[A-z]*', 'match')
I think you'll be able to find the rest out yourself :)
Here is basic skeleton. But make sure to use correct regexp to extract the values ;-)
Yes with the above Dorin's regexp and match you get one value at a time. You may add a token as per this example from mathworks.
Sample:
str = ['if <code>A </code> == x<sup>2 </sup>, ' ... '<em>disp(x) </em>']
str = if <code>A </code> == x<sup>2 </sup>, <em>disp(x) </em>
expr = '<(\w+).*?>.*?</\1>';
[tok mat] = regexp(str, expr, 'tokens', 'match');
tok{:}
ans = 'code'
ans = 'sup'
ans = 'em'
in above code you don't really need to loop and can process entire text bulk as one string , hopefully not hitting any string limit......
But if you want to loop, or if you need to loop, you use the following sample with Rody's regexp and match only.
fid = fopen('data.txt');
dataText = fgetl(fid);
while ~feof(fid)
ldata = textscan(dataText,'*%d#*');
X = (ldata, '#[A-z]*', 'match')
Cellarray = X{1}
end
Disp(X)
fclose(fid);
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Regular Expression to match outer brackets
Can I use Perl regular expressions to match balanced text?
i would like to extract a whole text which has matching numbers of closing brackets. Here is the example text.
Big String 1 {sub string 1 {{something} something {}} sub string 2{something} sub string {{something}{something else}}}
Is there an easy way for me to extract whole string which belongs to Big String 1 only? The results i would like to have is as such:
Big String 1 = "sub string 1 {{something} something {}} sub string 2{something} sub string {{something}{something else}}"
Thanks,