How to move a given number of random files on Unix/Linux OS

Question

I'm facing this simple task but, I'm also wondering about what's the easiest and short way to do it.

My proposal is move a given numer of random files from a directory to another. This task is part of the creation of two datasets I need for machine learning: a training set and a testing set. My goal is move away 10% of the file from a directory in order to get the datasat agaist which I could test my categorizer, and obtain a training set from the source directory.

So, what's the most compact typing for this "move n random files" task?

Thanks in advance - as usual -

Answer 1

Use a combination of shuf and xargs (it's a good idea to look at their documentation with man):

shuf -n 10 -e * | xargs -i mv {} path-to-new-folder 

The command above selects 10 random files of the current folder (the * part) and then move them to the new folder.

Update

Although longer, one might find this version even simpler to understand:

ls | shuf -n 10 | xargs -i mv {} path-to-new-folder 

shuf just generates a random permutation of the standard input, limiting the results to 10 (like using head, but probably faster).

Answer 2

You could use bash random generator that generates an int between 0 and 32767 to choose if a file must be put in set1 or set2. That would do:

for file in ./*; do
  val=$RANDOM
  if test $val -gt 3276; then
    mv "$file" ../set1
  else
    mv "$file" ../set2
  fi
done

Answer 3

Alternative version with find to avoid problems with folders. It copies 31415 randomly chosen files into /home/user/dir/

find . -maxdepth 1 -type f | sort -R | head -31415 | xargs cp -t /home/user/dir/