Commands

 > dim(mydata)
  [1] 29363    12

 > colnames(mydata)
  [1] "gene_ID"            "Danio_match"        "Danio_symbol"
  [4] "exonic.length..bp." "brain"              "spinal"
  [7] "kidney"             "heart"              "sk..muscle"
  [10] "main.EO"            "Sach.s.EO"          "Hunter.s.EO"

 > names(mydata)

 > head(mydata)
       gene_ID        Danio_match Danio_symbol exonic.length..bp. brain spinal
 1 C7653330.g1 ENSDARG00000000503        stx1b                458 838.7   85.1
 2 C7653792.g1 ENSDARG00000061600        tmem2                227   7.0   36.8
 3 C7653898.g1 ENSDARG00000013526        SVEP1                177 112.1   10.5
 4 C7654004.g1 ENSDARG00000042892        paip1                288 636.6  522.2
 5 C7655006.g1 ENSDARG00000075118           SI                152 313.3   54.9
 6 C7655900.g1                                                139  11.4   26.7
   kidney  heart sk..muscle main.EO Sach.s.EO Hunter.s.EO
 1    0.0   18.7       83.4     6.1       6.1         4.4
 2  151.2   75.4      221.5    61.9     156.2       191.4
 3   28.5  193.4       34.1    21.2      52.7        57.1
 4  771.0 1007.2     1871.8   982.4    1059.3      1326.2
 5   46.4   93.9      158.8    55.5     239.4       119.7
 6   29.1  198.4      188.1    27.0      67.1       152.7


 > head(mydata$gene_ID)
 [1] C7653330.g1 C7653792.g1 C7653898.g1 C7654004.g1 C7655006.g1 C7655900.g1
 29363 Levels: C7653330.g1 C7653792.g1 C7653898.g1 C7654004.g1 ... scaffold9.g1