Randomly accessing a file from a folder using Matlab

I am trying to randomly access a file from a folder using matlab, could you suggest me that how shall i go about, i am planning to use randn function? but i dnt understand i shall i merge it !

Answer 1

[Geoff]

I understand your question in two different ways:

1. You want to choose a random file from a specified folder

2. You want to choose a random position in a single file in a folder.

I use randi here, but if you want to use randn you probably need to find a way to turn that into an integer. It's unusual to want to use a normal distribution for something like you seem to be describing though.

So...

If (1) Use the dir command to list files in that folder:

f = dir( myfolder );
ridx = randi(numel(f));
disp( ['Chosen file is: ' f(ridx).name] );

If (2) Open your file and determine its size, then seek to random position:

fid = fopen( myfile, 'rb' );
fseek(fid, 0, 'eof' );
fsize = ftell(fid);
rpos = randi(fsize)-1;
fseek(fid, rpos, 'bof');
...
fclose(fid);

[KT]

yes i wanted to do what you mentioned in your option 1 , thank you so much,could you tell me that i have 5 files in my folder, but when i use *numel* , it gives 7 instead of 5, where two files were turning out to be in the form of *..* so do you know the reason for it?