title: merge data frame with vector in R
body: <p>Based on a t-test on gene expression data from microarray (with the EMA package) and subsequent annotation I generated a data frame that looks like this:</p>
  
  <pre><code>&gt;
  
   head(rt.annot)
        affy_hg_u133_plus_2     probeID      Stat    RawpValue    AdjpValue entrezgene hgnc_symbol ensembl_gene_id
  14744           204103_at   204103_at 11.754856 1.718688e-20 9.396926e-16       6351        CCL4 ENSG00000275302
  721            1553177_at  1553177_at 10.358405 1.810027e-17 4.948161e-13     117157      SH2D1B ENSG00000198574
  16279         205495_s_at 205495_s_at  9.909715 1.721748e-16 3.137886e-12      10578        GNLY ENSG00000115523
  21763           210163_at   210163_at  9.496225 1.374429e-15 1.623589e-11         NA        &lt;NA&gt;            &lt;NA&gt;
  44641           230464_at   230464_at  9.480850 1.484763e-15 1.623589e-11      53637       S1PR5 ENSG00000180739
  18998           207840_at   207840_at  9.383745 2.417818e-15 1.652428e-11      11126       CD160 ENSG00000117281
  </code></pre>
  
  <p>with 60376 rows and 8 columns. </p>
  
  <p>I also measured the fold change of gene expression between the 2 groups, this generated a vector: </p>
  
  <pre><code>&gt; head(fcOUT)
  1007_s_at   1053_at    117_at    121_at 1255_g_at   1294_at 
  0.9436815 1.0098279 1.0230719 0.9826041 0.9917645 1.0906764 
  </code></pre>
  
  <p>How do I merge the data frame (rt.annot) and vector (fcOUT) (so that the vector is aligned as a column to the matrix, based on the first column aafy_hg_u133_plus_2 (thus not as cbind function))?
  I could not find the answer elsewhere.</p>
  
  <p>Thank you!</p>