digraph PCA {
  var1[shape=box];
  var2[shape=box];
  var3[shape=box];
  var4[shape=box];
  var5[shape=box];
  var6[shape=box];
  pc1[label="principal component1"];
  pc2[label="principal component2"];
  var1 -> pc1;
  var2 -> pc1;
  var3 -> pc1;
  var4 -> pc1;
  var5 -> pc1;
  var6 -> pc1;
  var1 -> pc2;
  var2 -> pc2;
  var3 -> pc2;
  var4 -> pc2;
  var5 -> pc2;
  var6 -> pc2;
}