title: Create 2 vectors where 1 vector is associated with another, then converted into a list
body: <p>I am new to R so please be nice to me. I have a vector called flood that is associated with flood_level. I have another vector called year that must be associated with flood_level, which is associated with flood. In the end, all of this must come together in list format, like so: 
  <a href="https://i.stack.imgur.com/U4jBX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/U4jBX.png" alt="enter image description here"></a></p>
  
  <p>I am having trouble getting to the result in the picture and I don't know what code to type to get there. Please help me figure out what I'm doing wrong. Here is my code:</p>
  
  <pre><code>flood = c(1,2,3,3,2,1,2,2,3,1,1,1,1,3,2)
  flood_level = factor(flood, labels = c("low", "medium", "high"))
  year = c(2001:2015)
  my_df = data.frame(year, flood_level)
  my_df
  flood_year = as.list(my_df)
  </code></pre>