How to draw Clusters of Orthologous Groups (COG) b

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How to combine different barplot in R? 1 answer

I am new to R and I have some data as below and I want to draw a histogram same as this with pkg::ggplot2 in R program (linux or Rstudio).

As you can see it is the letters from A to Z in the X axis (Function class) and the frequencies as numbers in the Y and the important point is this that each bar has its own unique color.

In addition, there is a "color help = legend" that describe each class by the same color of each bars that I am not sure if it is some characteristics of R ggplot2 package or not?

I have checked some online helps but I do not know how to insert my data in the ggplot2 and assign a unique color for each class.

my data sample:

A   5   RNA processing and modification 
B   2   Chromatin structure and dynamics 
C   18  Energy production and conversion 
D   26  Cell cycle control, cell division, chromosome partitioning
E   15  Amino acid transport and metabolism 
F   5   Nucleotide transport and metabolism 
G   13  Carbohydrate transport and metabolism 
H   6   Coenzyme transport and metabolism 
I   15  Lipid transport and metabolism 
J   20  Translation, ribosomal structure and biogenesis 
K   24  Transcription 
L   28  Replication, recombination and repair
M   18  Cell wall/membrane/envelope biogenesis 
N   1   Cell motility 
O   29  Posttranslational modification, protein turnover, chaperones 
P   19  Inorganic ion transport and metabolism 
Q   16  Secondary metabolites biosynthesis, transport and catabolism 
R   85  General function prediction only 
S   20  Function unknown 
T   32  Signal transduction mechanisms 
U   14  Intracellular trafficking, secretion, and vesicular transport 
V   6   Defense mechanisms 
Z   14  Cytoskeleton

Are those numbers next to the letters A-Z the height of the bars? If so, you're better of using a barplot:

library(ggplot2)
# Simulate some data
obs = rpois(10, 5)
group = factor(1:10)
df = data.frame(obs, group)
ggplot(data = df, aes(x = group, y = obs, color = group, fill = group)) + 
  geom_bar(stat = 'identity')

To get the colored bars in general, make sure your dataframe has a grouping variable (must be a factor, otherwise you get continuous color assignment) and then in aes assign color/fill the value of the column name.