title: Generate a set of random unique integers from an interval
body: <p>I am trying to build some machine learning models,</p>
  <p>so I need training data and a validation data</p>
  <p>so suppose I have N number of examples, I want to select random x examples in a data frame.</p>
  <p>For example, suppose I have 100 examples, and I need 10 random numbers, is there a way (to efficiently) generate 10 random INTEGER numbers for me to extract the training data out of my sample data?</p>
  <p>I tried using a while loop, and slowly change the repeated numbers, but the running time is not very ideal, so I am looking for a more efficient way to do it.</p>
  <p>Can anyone help, please?</p>