title: Reference variable name containing spaces within text in Rmarkdown
body: <p>Is there a way to reference columns of a data frame by name within a text block of a Rmarkdown document if the column name includes non-standard characters (for example a space)?</p>
  
  <p>If my one of my column names has a space like the example below, within a code block I can refer to the column by name by surrounding the name with backticks. But if I wanted to include the minimum of this column within the text block since you use backticks to indicate that you are using a code call, so the backticks act as escapes. So `min(my.df$`temp C`)` throws an error because it escapes the code execution.</p>
  
  <pre><code>my.df &lt;- data.frame(id = 1:5, 
                      label = LETTERS[1:5],
                      `temp C` = rnorm(5, mean = 15))
  colnames(my.df)[3] &lt;- "temp C"
  my.df$`temp C`
  # [1] 15.78235 15.51955 14.58482 14.34349 14.38736
  
  min(my.df$`temp C`)
  # [1] 14.34349
  </code></pre>
  
  <p>I could use <code>min(my.df[,3])</code>, but since the data is from an external source, it would silently return the wrong result if the order of the columns in the source file changes.  I tried escaping the backtick character in the text block using "\", but it didn't work.  Is there an alternate escape character, or some other way to reference a column by name within the text block?</p>
  
  <p>The other approach I thought of using was to create a variable within the a code block before I look to reference it in-line, but this seems a little clunky.  </p>