What you are trying to do is called asparse checkout, and that feature was added in git 1.7.0 (Feb. 2012). The steps to do a sparse_clone_are as follows:

Now you need to define which files/folders you want to actually check out. This is done by listing them in.git/info/sparse-checkout, eg:

mkdir tensorflow
cd tensorflow

git init
git remote add -f origin https://github.com/powertsai/tensorflow

git config core.sparseCheckout true

echo "tensorflow/examples/udacity" >> .git/info/sparse-checkout

Last but not least, update your empty repo with the state from the remote:

git pull origin master