title: stringr extract full number from string
body: <p>From <code>?stringr::str_extract</code>, I tried</p>
  
  <pre><code> library(stringr)
   str_extract("number 123", "\\d")
   # [1] "1"
  </code></pre>
  
  <p>but I'd like the full number <code>123</code>. I couldn't find the correct regular expression, or another function to perform this task. My workaround is a bit ugly,</p>
  
  <pre><code>as.numeric(str_split("number 123", " ")[[1]][2])
  # [1] 123
  </code></pre>