title: Create empty tibble/data frame with column names coming from a vector
body: <p>I would like to create an empty data frame where the column names are coming from a character vector. </p>
  
  <p>for example, if this was my vector:</p>
  
  <pre><code> vec &lt;- letters[1:3]
  </code></pre>
  
  <p>I would like create an empty data frame like the following:</p>
  
  <pre><code> df &lt;- tibble('a' = character(), 'b' = character(), 'c' = character())
  </code></pre>
  
  <p>however, I would like to iterate through the items in the vector to populate the dataframe names and not have to manually specify each one. In reality my vector has 40+ names. </p>
  
  <p>I've tried the following by they don't work:</p>
  
  <pre><code> df &lt;- tibble(vec[1:3])
   df &lt;- tibble(vec)
   df &lt;- tibble(for (i in 1:3){
     vec[i]
   })
  </code></pre>
  
  <p>Any help on this would be greatly appreciated!</p>