title: How to retain the first observation in every 30 days in the dataset for each ID?
body: <p>I have a dataset in which I need to keep the first incidence in the database and remove what happens in 30 days window after and redo the process again. Here is a demonstration</p>
  <p><a href="https://i.stack.imgur.com/1zmi3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1zmi3.png" alt="enter image description here" /></a></p>
  <p>I want to keep all the rows with arrows and exclude the other ones.</p>
  <p>Any help would be really appreciated.</p>
  <p>Thanks</p>