title: Format number as fixed width, with leading zeros
body: <p>The following code</p>
  
  <pre><code>a &lt;- seq(1,101,25)
  b &lt;- paste("name", 1:length(a), sep = "_")
  </code></pre>
  
  <p>produces this output:</p>
  
  <pre><code>"name_1"  "name_26"  "name_51"  "name_76"  "name_101"
  </code></pre>
  
  <p>I'd like to have the same width of all values which means for me to fill the values with zeros like this:</p>
  
  <pre><code>"name_001"  "name_026"  "name_051"  "name_076"  "name_101"
  </code></pre>
  
  <p>How do I handle that?</p>
  
  <p><sub>(This question is related to <a href="https://stackoverflow.com/questions/8260808/transpose-reshape-rows-in-coloums-with-given-conditions">this one</a>.)</sub></p>