title: How to name first unnamed column header of a data frame in R
body: <p>I have the following data frame </p>
  
  <pre><code>df &lt;- structure(c("1450783_at Ifit1", "1417793_at Irgm2", "1418191_at Usp18",
  "1445897_s_at Ifi35", "1438868_at Phf11d", "1438004_at Papd7",
  "-0.946463848219996", "-1.02996255295994", "-1.08671744204772",
  "-0.99957964419579", "-0.823103726651139", "-0.879596943746683",
  "-0.81666670993138", "-0.751419221027377", "-0.771297530228225",
  "-0.788962065407382", "-0.845247178175189", "-0.836283457880369",
  "0.670196443309756", "0.654252942446252", "0.760493091259822",
  "0.810593059985653", "0.701631078290633", "0.732997453122236",
  "1.380387289393", "1.37328340394659", "1.27108996508917", "1.27736715351672",
  "1.39124142575392", "1.35937709488124", "-0.287453174551374",
  "-0.246154572405521", "-0.173568084073049", "-0.299418503899194",
  "-0.424521599218227", "-0.376494146376421"), .Dim = c(6L, 6L), .Dimnames = list(
      c("1450783_at Ifit1", "1417793_at Irgm2", "1418191_at Usp18",
      "1445897_s_at Ifi35", "1438868_at Phf11d", "1438004_at Papd7"
      ), c("", "(3)ADX.ID.LN.x1", "(3)ADX.ID.LN.x2", "(3)ALM.ID.LN.x2",
      "(3)ALM.ID.LN.x1", "(3)ALM.ID.LN.x3")))
  </code></pre>
  
  <p>Which looks like this:</p>
  
  <pre><code>&gt; df 
                                          (3)ADX.ID.LN.x1      (3)ADX.ID.LN.x2     
  1450783_at Ifit1   "1450783_at Ifit1"   "-0.946463848219996" "-0.81666670993138" 
  1417793_at Irgm2   "1417793_at Irgm2"   "-1.02996255295994"  "-0.751419221027377"
  1418191_at Usp18   "1418191_at Usp18"   "-1.08671744204772"  "-0.771297530228225"
  1445897_s_at Ifi35 "1445897_s_at Ifi35" "-0.99957964419579"  "-0.788962065407382"
  1438868_at Phf11d  "1438868_at Phf11d"  "-0.823103726651139" "-0.845247178175189"
  1438004_at Papd7   "1438004_at Papd7"   "-0.879596943746683" "-0.836283457880369"
                     (3)ALM.ID.LN.x2     (3)ALM.ID.LN.x1    (3)ALM.ID.LN.x3     
  1450783_at Ifit1   "0.670196443309756" "1.380387289393"   "-0.287453174551374"
  1417793_at Irgm2   "0.654252942446252" "1.37328340394659" "-0.246154572405521"
  1418191_at Usp18   "0.760493091259822" "1.27108996508917" "-0.173568084073049"
  1445897_s_at Ifi35 "0.810593059985653" "1.27736715351672" "-0.299418503899194"
  1438868_at Phf11d  "0.701631078290633" "1.39124142575392" "-0.424521599218227"
  1438004_at Papd7   "0.732997453122236" "1.35937709488124" "-0.376494146376421"
  </code></pre>
  
  <p>What I want to do is to name the first unamed columns with "ProbeGene".
  So that it looks like this:</p>
  
  <pre><code>                       ProbeGene                 (3)ADX.ID.LN.x1      (3)ADX.ID.LN.x2     
  1450783_at Ifit1   "1450783_at Ifit1"   "-0.946463848219996" "-0.81666670993138" 
  </code></pre>
  
  <p>How can I achieve that?</p>
  
  <p>I tried this <code>names(df)[1] &lt;- "ProbeGene"</code> but failed.</p>