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R function: barplot

Visualize the values of a vector

In its simplest form, barplot can be used to visualize the values in a vector.

vec <- c(2, 1, 2, 4, 4, 1, 2, 2, 1, 3, 4, 2);

barplot(vec);

Github repository about-r, path: /functions/barplot/vector.R

Counting occurrences of elements

The elements in a vector can be counted with table and the bar-plotted which reveals how often a specific element (string) occurs in the vector:

things <- c(
    'socks' ,
    'chairs',
    'socks' ,
    'lamps' ,
    'chairs',
    'socks' ,
    'socks'
);

countOfThings <- table(things);

print(countOfThings);
#
# things
# chairs  lamps  socks 
#      2      1      4 

barplot(countOfThings);

Github repository about-r, path: /functions/barplot/count-things.R

Naming (labeling) bars

With names, the elements in a vector can be given a name which will then be displayed below the bars in the plot:

      prices  <- c(  81 ,   76 ,   92 );
names(prices) <- c('Foo', 'Bar', 'Baz');

barplot(prices, main='Prices', ylab='Euros');

Github repository about-r, path: /functions/barplot/naming-bars.R

Limitting the y range

      prices  <- c(  81 ,   76 ,   92 );
names(prices) <- c('Foo', 'Bar', 'Baz');

barplot(prices, main='Prices', ylab='Euros', ylim=c(70, 95), xpd=FALSE) # xpd: Should bars be allowed to go outside region?

Github repository about-r, path: /functions/barplot/ylim.R

Adding the values of the bars to plot

set.seed(28)
values = round(rnorm(6, 18, 3.5), 1);
names(values) <- c('abc', 'def', 'ghi', 'jkl', 'mno', 'pqr');

y_coords = barplot(values)

text(y_coords, values, labels=values, pos=1)

Github repository about-r, path: /functions/barplot/add-values.R

Displaying multiple barplots besides each other

val_1 <-  (1:10) - 3
val_2 <- ((1:10) + 5) / 2

barplot (
  cbind(val_1, val_2),
  beside =  TRUE,
  names  = c('Values one', 'Values two')
);

Github repository about-r, path: /functions/barplot/beside-true.R