title: How to change the color spectrum pattern of fill() in ggplot2 bar chart?
body: <p>Hi.</p>
  
  <p>I  have a ggplot2 script which I will show it at the end of my question and I have created it with the help of other friends <a href="https://stackoverflow.com/questions/39613006/how-to-add-main-title-and-manipulating-axis-labels-in-ggplot2-in-rstudio?noredirect=1&amp;lq=1">from here</a>.</p>
  
  <p>but its color spectrum is not satisfying for me. </p>
  
  <p>In my old "barplot()" script, I had a line that shows the different color spectrum for each bar -> "<strong>col=c(fill = rainbow(25)),</strong>" and this rainbow colors was different from the <strong>color spectrum</strong> of <strong>ggplot(fill=legend)</strong>. Is there any way to use that rainbow spectrum which <strong>begins with red instead of ggplot2 spectrum that begins with orange, in my recent ggplot2 script?</strong> 
  if it is possible, please add the appropriate lines in my script or mention the scripts and the position that I have to insert them because I have tried several instances and they did not work for me &amp; it seems that the please of each command has some effect on the whole program.</p>
  
  <p>Thank you in advance</p>
  
  <pre><code>        dat &lt;- data.frame(
    FunctionClass = factor(c("A", "B", "C", "D", "E", "F", "G", "H", "I",     "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "Y", "Z"), levels=c("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "Y", "Z")),
    legend = c("A: RNA processing and modification", "B: Chromatin structure and dynamics", "C: Energy production and conversion", "D: Cell cycle control, cell division, chromosome partitioning", "E: Amino acid transport and metabolism", "F: Nucleotide transport and metabolism", "G: Carbohydrate transport and metabolism", "H: Coenzyme transport and metabolism", "I: Lipid transport and metabolism", "J: Translation, ribosomal structure and biogenesis", "K: Transcription", "L: Replication, recombination and repair", "M: Cell wall/membrane/envelope biogenesis", "N: Cell motility", "O: Posttranslational modification, protein turnover, chaperones", "P: Inorganic ion transport and metabolism", "Q: Secondary metabolites biosynthesis, transport and catabolism", "R: General function prediction only", "S: Function unknown", "T: Signal transduction mechanisms", "U: Intracellular trafficking, secretion, and vesicular transport", "V: Defense mechanisms", "W: Extracellular structures", "Y: Nuclear structure", "Z: Cytoskeleton"),
    Frequency=c(360,391,897,1558,1168,448,1030,536,732,1292,2221,2098,789,117,1744,732,437,5162,1251,2191,603,216,2,14,739)
  )
  
  library(ggplot2)
  p &lt;- ggplot(data=dat, aes(x=FunctionClass, y=Frequency, fill=legend))+
  geom_bar(stat="identity", position=position_dodge(), colour="seashell")
  p + guides (fill = guide_legend(ncol = 1))+
  xlab("Factor Class")+
  ggtitle("COG Function Classification of Consensus Sequences")
  </code></pre>