# Plotting with R (Part II)

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In Plotting with R (Part I), I summarized the functions that can be used in R plotting. In this part, we continue the journey to plot more rich and complex charts like Pie Chart, Bar Chart, BoxPlot, Histogram, Line and Scatterplot using those functions.

### Pie chart

Pie chart can be drawn using the following function:

pie(x, labels, radius, main, col, clockwise)

#### Pie chart with legends

The following code snippet (script *R28.PieChart.R*) draws a pie chart with legends:

# Draw pie charts ( data <- data.frame(Quarter=c('1st Qtr','2nd Qtr', '3rd Qtr','4th Qtr'), Sales=c(8.2,3.2,1.4,1.2)) ) # create image device #png(file="R28.PieChart.png") # percentage calculation percentage <- paste(as.character( round(data$Sales/sum(data$Sales)*100, 1)), "%", sep="") # colors colors <- terrain.colors(length(data$Sales)) # draw pie(data$Sales, labels = percentage, main="Sales", col = colors) # legends legend("topright", legend = data$Quarter, cex=0.8, fill = colors)

The output looks like the following screenshot:

#### 3D pie chart

We can use package **plotrix **to draw 3D pie chart:

# 3D Chart if("plotrix" %in% installed.packages()) { print("plotrix is installed.") }else { print("plotrix is not installed.") install.packages("plotrix") } require(plotrix) pie3D(data$Sales, labels = percentage, main="Sales", col = colors) # legends legend("topright", legend = data$Quarter, cex=0.8, fill = colors)

### Bar chart

Bar chart can be drawn using the following function:

barplot(H, xlab, ylab, main, names.arg, col)

The following code snippets (script R29.BarChart.R) draws bar charts using this function with different parameter values.

#### Plot bar chart

# Draw bar charts Quarter <- c('1st Qtr','2nd Qtr', '3rd Qtr','4th Qtr') ( data <- data.frame(Quarter=Quarter, Sales=c(8.2,3.2,1.4,1.2)) ) # colors colors <- terrain.colors(length(data$Sales)) # draw barplot(data$Sales, names.arg = data$Quarter, main="Sales", col = colors, xlab="Quarter", ylab="Sales ($m)") # legends legend("topright", legend = data$Quarter, cex=0.8, fill = colors)

The chart looks like the following:

#### Plot stacked bar chart

Matrix can be used as input for drawing stacked bar chart:

# Stacked bar chart Year <- c(2015,2016,2017) # Use matrix ( data <- matrix(c(8.2,3.2,1.4,1.2,9.2,1.2,5.4,3.2,1,3,4,6), nrow=4, ncol = 3) ) # draw barplot(data, names.arg = Year, main="Sales", col = colors, xlab="Year", ylab="Sales ($m)") # legends legend("topright", legend = Quarter, cex=0.8, fill = colors)

The chart looks like the following screenshot:

### Box chart

Boxplots are a measure of how well distributed is the data in a data set. It divides the data set into three quartiles. This graph represents the minimum, maximum, median, first quartile and third quartile in the data set. It is also useful in comparing the distribution of data across data sets by drawing boxplots for each of them.

boxplot(x, data, notch, varwidth, names, main)

The following code snippet (script *R30.BoxPlot.R*) draw a boxplot chart with test data set:

# Box Plot #A data frame with 32 observations on 11 variables. # #[, 1] mpg Miles/(US) gallon #[, 2] cyl Number of cylinders #[, 3] disp Displacement (cu.in.) #[, 4] hp Gross horsepower #[, 5] drat Rear axle ratio #[, 6] wt Weight (1000 lbs) #[, 7] qsec 1/4 mile time #[, 8] vs V/S #[, 9] am Transmission (0 = automatic, 1 = manual) #[,10] gear Number of forward gears #[,11] carb Number of carburetors # Plot the chart. boxplot(wt ~ cyl, data = mtcars, xlab = "Cylinders #", ylab = "Weight (1000 lbs)", main = "Weight and Cylinders Data", col=terrain.colors( length(unique(mtcars$cyl))))

### Histogram chart

A histogram represents the frequencies of values of a variable bucketed into ranges. Histogram is similar to bar chat but the difference is it groups the values into continuous ranges. Each bar in histogram represents the height of the number of values present in that range.

hist(v,main,xlab,xlim,ylim,breaks,col,border)

*R31.Histogram.R*) of plotting histogram using generated data (one via

**rnorm**and another via

**sample**):

# Histogram # prepare data ( data1 <- rnorm(200,mean=40,sd=10) ) hist(data1, col=c("green")) ( data2 <- sample.int(500,200) ) hist(data2, col=c("green"))

*info*We can tell from the chart that

**rnorm**does generate a sequence of data elements (variable) that aligns with normal distribution.

### Line chart

Line can be drawn using the following functions:

plot() lines()

*R32.Line.R*) draws a simple line chart:

# Line chart Quarter <- c('1st Qtr','2nd Qtr', '3rd Qtr','4th Qtr') ( data <- data.frame(Quarter=Quarter, Sales=c(8.2,3.2,1.4,1.2)) ) # colors colors <- "green" # draw plot(data$Sales, main="Sales", col = colors, xlab="Quarter", ylab="Sales ($m)", type="o") #another line lines((1:4),rnorm(4,2,1), type="b", col="blue")

### Scatter chart

Scatterplots show many points plotted in the Cartesian plane. Each point represents the values of two variables. One variable is chosen in the horizontal axis and another in the vertical axis.

plot(x, y, main, xlab, ylab, xlim, ylim, axes) pairs() # create matrix of scatterplots.

The following code snippet (script *R33.Scatterplot.R*) shows how to use these two functions to draw Scatterplot:

# Scatterplot plot(y = mtcars$wt,x = mtcars$cyl, xlab = "Cylinder", ylab = "Weight", ylim = range(mtcars$wt), xlim = range(mtcars$cyl), main = "Weight & Cylinder #", col="green" ) # pairs pairs(~mpg+disp+cyl,data = mtcars, main = "Scatterplot Matrix", col="green")

The charts look like the following screenshots:

### Summary

There are many other charts that can be drawn in R. Refer to official documentation or help documents for more details.

*info*Last modified by Raymond 2 years ago

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