Dot plot in R also known as dot chart is an alternative to bar charts, where the bars are replaced by dots. A simple Dot plot in R can be created using dotchart function.

**Syntax of dotchart() function in R for Dot plot:**

NumericVector | Numeric vector to be plotted |

cex | plot scaling factor(size) . More the value of cex, more the plot size will be |

col | colour of the dot |

labels | A vector containing the label names for each plotted value. |

main | Title of the dot chart |

pch | numeric value which decides the type of plot … if pch=1 then dot, pch=2 then triangle, pch=3 then ‘+’ |

sub | subtitle of the dot chart |

xlab | x axis label |

**Example of dot plot in R **

We will use the PlantGrowth data set to depict an example of R dot plot

#simple dot plot in R dotchart(PlantGrowth$weight,col="red",pch=1,labels=PlantGrowth$group, main="group vs weight", xlab="weight")

the above dotchart() function takes up numeric vector as first argument and plots the red dots with labels and title. So the output will be

**Dot plot in R for groups:**

Suppose if we want to create the different dot plots for different group of the same data set, how to do that? For Example PlantGrowth data set have 3 groups ctrl, trt1 and trt2. Lets demonstrate how to differentiate among these 3 groups while plotting a dot chart

#Dot chart in R for groups #subset and assign colour pg <- PlantGrowth pg$color[pg$group=="ctrl"] <- "red" pg$color[pg$group=="trt1"] <- "Violet" pg$color[pg$group=="trt2"] <- "blue" # plot the dot chart dotchart(PlantGrowth$weight, labels=PlantGrowth$group,cex=0.8,groups= PlantGrowth$group, main="group vs weight", xlab="weight", gcolor="black", color=pg$color)

First subset the groups and assign different colour for different groups. Then with the help of dotchart() function use the argument, groups= **PlantGrowth$group** and color=** pg$color ** as shown above

So the output will be