Pareto chart, named after Vilfredo Pareto, is a type of chart that contains both bars and a line graph, where individual values are represented in descending order by bars, and the cumulative total is represented by the line. This type of chart is usefull in many ways and is in general a better idea to use Pareto Chart instead of pie chart since it reveals more information.

Data Preparation

Assume we have some defect counts for different sources.

##   category defect
## 1    price     80
## 2 schedule     27
## 3 supplier     66
## 4  contact     94
## 5     item     33

To prepare data for Pareto Chart we need to sort counts in decreasing order, calculate cumulative sum and cumulative frequency of the counts. This can be done in variety of ways in R. In the example below preparation is done with dplyr R package.

## Data preparation
suppressPackageStartupMessages(library(dplyr))

d <- arrange(d, desc(defect)) %>%
        mutate(
                cumsum = cumsum(defect),
                freq = round(defect / sum(defect), 3),
                cum_freq = cumsum(freq)
               )
d
##   category defect cumsum  freq cum_freq
## 1  contact     94     94 0.313    0.313
## 2    price     80    174 0.267    0.580
## 3 supplier     66    240 0.220    0.800
## 4     item     33    273 0.110    0.910
## 5 schedule     27    300 0.090    1.000

Pareto Chart: Version 1

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## R code to generate Pareto Chart (version 1)

## Saving Parameters 
def_par <- par() 

## New margins
par(mar=c(5,5,4,5)) 

## bar plot, pc will hold x values for bars
pc = barplot(d$defect,  
             width = 1, space = 0.2, border = NA, axes = F,
             ylim = c(0, 1.05 * max(d$cumsum, na.rm = T)), 
             ylab = "Cummulative Counts" , cex.names = 0.7, 
             names.arg = d$category,
             main = "Pareto Chart (version 1)")

## Cumulative counts line 
lines(pc, d$cumsum, type = "b", cex = 0.7, pch = 19, col="cyan4")

## Framing plot
box(col = "grey62")

## adding axes
axis(side = 2, at = c(0, d$cumsum), las = 1, col.axis = "grey62", col = "grey62", cex.axis = 0.8)
axis(side = 4, at = c(0, d$cumsum), labels = paste(c(0, round(d$cum_freq * 100)) ,"%",sep=""), 
     las = 1, col.axis = "cyan4", col = "cyan4", cex.axis = 0.8)

## restoring default paramenter
par(def_par)

Pareto Chart: Version 2

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## ## R code to generate Pareto Chart (version 2)

## Saving Parameters 
def_par <- par() 

# New margins
par(mar=c(5,5,4,5)) 

## plot bars, pc will hold x values for bars
pc = barplot(d$defect,
             width = 1, space = 0.2, border = NA, axes = F,
             ylim = c(0, 1.05 * max(d$defect, na.rm = T)), 
             ylab = "Counts" , cex.names = 0.7, 
             names.arg = d$category,
             main = "Pareto Chart (version 2)")

## anotate left axis
axis(side = 2, at = c(0, d$defect), las = 1, col.axis = "grey62", col = "grey62", tick = T, cex.axis = 0.8)

## frame plot
box( col = "grey62")

## Cumulative Frequency Lines 
px <- d$cum_freq * max(d$defect, na.rm = T)
lines(pc, px, type = "b", cex = 0.7, pch = 19, col="cyan4")

## Annotate Right Axis
axis(side = 4, at = c(0, px), labels = paste(c(0, round(d$cum_freq * 100)) ,"%",sep=""), 
     las = 1, col.axis = "grey62", col = "cyan4", cex.axis = 0.8, col.axis = "cyan4")

## restoring default paramenter
par(def_par)