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rbar-chart
Klausos Klausos
Klausos Klausos

Reputation: 16050

How to create a bar plot and show average Y values

I want to create a bar plot based on the following data:

Station    Delay
A          5
B          6
A          4
A          3
B          8

X axis should contain stations "A" and "B", while bars (Y axis) should show average delay per a station.

I tried this, but it does not give a correct result:

barplot(c(data$Station, data$Delay), 
        main="BARPLOT", xlab="Stations", ylab="Delays", 
        names.arg=data$Station)

Upvotes: 2

Views: 19146

Answers (2)

Mateusz1981
Mateusz1981

Reputation: 1867

df <- data.frame(Station = c("A", "B", "A", "A", "B"),    Delay= c(5, 6, 4, 3, 8))

library(dplyr)
df <- df %>% group_by(Station) %>% summarise(me = mean(Delay))
library(ggplot2)
ggplot(aes(x = Station, y = me), data = df) + geom_bar(stat = "identity")

enter image description here

or directly with stat_summary

ggplot(aes(x = Station, y = Delay), data = df) + stat_summary(fun.y = "mean", geom = "bar")

Upvotes: 4

Cath
Cath

Reputation: 24074

In base R, you can do:

m_data <- data.frame(data$Station, m_del=ave(data$Delay, data$Station), stringsAsFactors=F)
barplot(unique(m_data)$m_del, names=unique(m_data)$Station, main="BARPLOT", xlab="Stations", ylab="Delays")

Or with the package data.table, you can do:

library(data.table)
m_data <- setDT(data)[, mean(Delay), by=Station]
m_data[, barplot(V1, names=Station, main="BARPLOT", xlab="Stations", ylab="Delays")]

enter image description here

Upvotes: 1

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