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Hi all,
I am new in Matlab.
My code can only run if i change the filenames to m1,m2......Code:for img=1:5
a=imread(['input\m',int2str(img),'.pgm']);
:
:
imwrite(I2,['result\m',int2str(img),'.pgm']);
end
Before this, my filename is m-001-1.pgm,.....,m-002-1.pgm,...,m-003-1.pgm....
Is there any way to make a loop to read this original filename?
I have done this in C by searching for m*.pgm, then all the files with "m" in front will be read. How about Matlab?
Quote:
Originally Posted by tommy_chai
Yes you can do this in matlab. Here is the code (in general):
Hope this helps u.Code:dirName = 'MyDir';
D = dir(dirName); % check dir command, in matlab documentation
for (i=3:length(D)) % for each file in the directory (1 and 2 are '.' and '..')
if ( strcmp(D(i).name(end-3:end), '.pgm') == 1) % check if the extension of the current filename is '.pgm'
a=imread(D(i).name);
.......
end
end
:wave:
Sorry I have some problem with my matlab and cannot the software cannot be used in this period. According to what i have searched, this is what i understand (as shown in below.
Do you mind to clear my doubts here even if i haven't try to run it in Matlab (waiting for the software and computer to be fixed)?
for() is used to loop all the files inside the directory, right?
Is it ust an example that u start with "3" or any other meanings? Normally we start with "1" like for(i=1:length(D). I am afraid that i miss out something and didn't get your real meaning.
I have checked the "end" fuction but i can't understand in "(end-3:end)", do you mind to educate me on this?
These are my doubts. Thank you.Code:dirName = 'MyDir'; %name of the directory
D = dir(dirName); %command to check files in directory
for (i=3:length(D)) % a loop of how many file in such directory
if ( strcmp(D(i).name(end-3:end), '.pgm') == 1) % string compare
a=imread(D(i).name);
.......
end
end
Best regards,
Tommy
Hi!
Yes for() is used for looping through all files of the directory. We start at 3 because the 1st file of ANY directory is the '.' and the 2nd is the '..' directory, just like when you type "dir" or "ls" in Dos/Unix.Quote:
Originally Posted by tommy_chai
End is used in matlab at the end of commends, like if, while, for etc. Though, in the (end-3:end) it is used as matrix indexing: this means the 4 last elements of the array "D(i).name" (i.e. the current file name) are used and then compared to the .pgm extension.Quote:
Originally Posted by tommy_chai
Hope this gave u a more detailed explanation.Code:...if ( strcmp(D(i).name(end-3:end), '.pgm') == 1)....
Feel free to ask any more questions.
Regards,
Theodore :wave:
Thanks for the explanation. Now i have a clearer view except for End.Quote:
Originally Posted by yiannakop
(end-3:end)
Do you mean "D(i).name" is the 4 elements?
What does "end-3" means?
Let's say the filename is "a.pgm". Do you mean the ".pgm" is the 4 elements? So the function compares the extension ".pgm" only? Does it compare the filename, "a" in this example?
Thank you.
Best regards,
Tommy
First of all, D(i).name is the whole file name. We want to compare the extension of each file name (i.e. of each D(i).name), because in the given folder you may have files of other types which you cannot read using imread. So in order to do this, we take the last 4 elements (i.e. the extension of the file). In general, Matlab has a very simple way of taking a subvector (or substring). Suppose you have a vector called str. By typing:Quote:
Originally Posted by tommy_chai
You take the elements 4 to 7 of the str array. In the same way, by typing:Code:str2 = str(4:7);
you take the elements N-3,N-2,N-1 and N of the string D(i).name, where N is the length of the array, which (only when used as above is given by the "end" keyword).Code:...D(i).name(end-3:end)...
In any case, you should also read a simple introductory Matlab tutorial (google for it), in order to get the basic of Matlab. For example:
http://www.mathworks.com/academia/st...ter/tutorials/
Regards,
Theodore
Sorry, if i caused any misunderstanding from my previous questions. Yup, i know D(i).name is the name of the file and a:b is from "a" part of the string to "b" part. Actually, what i want to ask before is why start with end-3?
Now i understand, N-3, N-2, N-1, N is the 4 elements from the filename to compare with ".pgm", right?
Yes, you are right there might be other file extensions as well in the same directory.
If my explantion above is correct, i guess i have no more doubts but to say thank you for your helps and explanations.
Thank you very much.
Best regards,
Tommy
Yes you are right.Quote:
Originally Posted by tommy_chai
Any time! :wave:Quote:
Originally Posted by tommy_chai
Hi. I forgot to say that it is better to use strcmpi() instead of strcmp(), in order to ignore case differences (e.g. .PNG files could be found...)
:wave:
Ops, thanks for the suggestions. If you have experience in template matching using matlab, please contribute a bit under my post in General Developer Topics section. Thank you very much for what you have shared.
Best regards,
Tommy