title: Placeholder for character vector in purrr:map?
body: <p>I am trying to iterate over a character vector "outcomes" </p>
  
  <pre><code>results &lt;- map(outcomes, run("Female", ., predictors))
  </code></pre>
  
  <p>"run" is a user-defined function and "Female" and predictors are additional arguments I pass to the function. Period does not seem to work as a placeholder for each element of outcomes :</p>
  
  <pre><code> Error in .f(.x[[i]], ...) : object '.' not found 
  </code></pre>
  
  <p>I would really like to use map instead of a loop.</p>