Search notes:
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);
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);
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');
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?
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)
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')
);
