title: I want to get row numbers of all rows in a dataframe where an element in a column contains an element in a vector
body: <p>I have a character vector which looks something like this </p>
  
  <pre><code>Categories = sample(make.unique(rep(letters, length.out = 5), sep=''))
  Categories
  [1] "d-" "e-" "c-" "a-" "b-"
  </code></pre>
  
  <p>I have a dataframe df which looks like:</p>
  
  <pre><code>df = data.frame(name = c(1:10), cat = paste(c(letters[1:10]), "-1", sep = ""))
  df
      name cat
  1     1   a-1
  2     2   b-1
  3     3   c-1
  4     4   d-1
  5     5   e-1
  6     6   f-1
  7     7   g-1
  8     8   h-1
  9     9   i-1
  10   10   j-1
  </code></pre>
  
  <p>I want to get row numbers in df in the order in which the elements of Categories are contained in the column "cat" in df. So, I want to get </p>
  
  <pre><code>dfRowNumbers
  [1] 4,5,3,1,2
  </code></pre>
  
  <p>How can I get that?</p>