title: how to make an average with SD across all combination
body: <p>I have a data like this</p>
  <pre><code>    df&lt;- structure(list(data = c(&quot;A&quot;, &quot;AA&quot;, &quot;AAA&quot;, &quot;AB&quot;, &quot;ABN&quot;, &quot;AHG&quot;, 
  &quot;ANBV&quot;), G1_1 = c(1677.1, 956, 57.7, 44.5, 1578.2, 1184.8, 1958.5
  ), G1_2 = c(1296.9, 1230.2, 68.4, 57.5, 925.1, 1275.7, 2143.6
  ), G2_1 = c(7012.5, 2087.9, 146.7, 80, 6278.5, 3076.9, 808), 
      G2_2 = c(13470.8, 3926.6, 226.5, 212.6, 12569.4, 6569, 2479.8
      ), Vok3_1 = c(911, 832.8, 50.8, 34.8, 916.6, 1358.5, 1540.4
      ), Vok3_2 = c(5121.9, 1029.6, 108.9, 135, 3624.5, 1971.3, 
      1851.4), Vok4_1 = c(5136.7, 892.1, 78, 60.4, 3106.6, 1578.6, 
      1132.1), Vok4_2 = c(6313.4, 1180.8, 112, 163.4, 4639.8, 2506.4, 
      879.1)), class = &quot;data.frame&quot;, row.names = c(NA, -7L))
  </code></pre>
  <p>what I am trying to do is to get the sd and median, I am unsuccessful</p>
  <p>here is what I try and what I am looking to get</p>
  <pre><code>df_med &lt;- as.data.frame(df %&gt;% group_by(data = substr(data, 1, 2,3,4)) %&gt;% summarise_all(funs(median)))
  </code></pre>
  <p>here is the way I want is to get the median or sd between each two column for each row , for instance the first two columns G1_1 and G1_2 and between G2_1 and G2_2 etc</p>
  <p>The output that I look for is like this</p>
  <pre><code>data    G1        G2         Vok3          Vok4
  A       1487    10241.65    3016.45   5725.05
  AA     1093.1   3007.25    931.2      1036.45
  AAA    63.05    186.6      79.85       95
  AB      51      146.3       84.9       111.9
  ABN    1251.65  9423.95     2270.55   3873.2
  AHG   1230.25   4822.95.    1664.9    2042.5
  ANBV    2051.05 1643.9      1695.9    1005.6
  </code></pre>