title: Give the 3 columns after column i a suffix
body: <p>I have a dataframe where some columnnames wouldn’t be clear if you don’t see the other columns. For example column ‘blue1’. It means the blue chair of designer Mal would cost 5 dollar.</p>
  <pre><code>data.frame(designer = c(&quot;mal&quot;, &quot;didi&quot;, &quot;yels&quot;, &quot;don&quot;),
             trashcan = c(1:4),
             chair = c(1:4), blue1 = c(5:8), yellow2 = c(6:9), orange3 = c(11:14),
             bedframe = c(5:8), blue4 = c(6:9), yellow5 = c(11:14), orange6 = c(16:19))
   
  # designer trashcan chair blue1 yellow2 orange3 bedframe blue4 yellow5 orange6
  # 1      mal        1     1     5       6      11        5     6      11      16
  # 2     didi        2     2     6       7      12        6     7      12      17
  # 3     yels        3     3     7       8      13        7     8      13      18
  # 4      don        4     4     8       9      14        8     9      14      19
   
   
  # would like to get
  # designer trashcan chair blue1_chair yellow2_chair orange3_chair bedframe blue4_bedframe yellow5_bedframe orange6_bedframe
  # 1      mal        1     1           5             6            11        5              6               11               16
  # 2     didi        2     2           6             7            12        6              7               12               17
  # 3     yels        3     3           7             8            13        7              8               13               18
  # 4      don        4     4           8             9            14        8              9               14               19
   
  </code></pre>
  <p>Things to know:</p>
  <ul>
  <li>a furniture always has 0 or 3 other colors (trashcan has 0 other colors).</li>
  <li>The 3 colors always come straight after the furniture it’s about.</li>
  <li>numbers behind color can be random</li>
  </ul>
  <p>Any suggestions?</p>