How to plot a subset of a dataframe in R ?

In this article, we will learn multiple approaches to plotting a subset of a Dataframe in R Programming Language. Here we will be using, R language’s inbuilt “USArrests” dataset.

Method 1: Using subset() function

In this method, first a subset of the data is created base don some condition, and then it is plotted using plot function. Let us first create the subset of the data.

Syntax: plot(subset( data, condition, select))  

Parameters:

data: dataframe

condition: indicates the logical expression on the basis of which subsetting has to be done

select: indicates columns to select

Example:

R

subset(USArrests, Assault > 100 & UrbanPop > 25,
       select = c( Rape, Assault))

Output:

   Rape Assault

Alabama        21.2     236

Alaska         44.5     263

.

.

.

Washington     26.2     145

Wyoming        15.6     161

Now let’s create the plot for the subset so obtained. The above command can be directly passed to the plot() function.

Example:

R

plot(subset(USArrests,Assault > 100 & UrbanPop > 25,
            select = c(Rape, Assault)))

Output:

Method 2: Using [ ] operator

Using the ‘[ ]’ operator, elements of vectors and observations from dataframes can be accessed and subsetted based on some condition.

Syntax: plot( df$col1[condition], df$col2[condition] )

Parameters: 

df: dataframe 

condition:  indicates the logical expression on the basis of which subsetting has to be done

Again the data will be first subsetted out and then will be provided to the plot() function.

Example:

R

plot(USArrests$Rape[USArrests$Assault > 100] ,
     USArrests$Assault[USArrests$Assault > 100] )

Output:

Method 3: Using attributes for rows and columns

In this we pass the row and column name to be plotted, and the condition based on which sub setting should be done to the plot function.

Syntax: plot( x ~ y, data=subset(df, condition ) )

Parameters:

x: data for x axis

y: data for y axis

data: subset of our dataframe which we want to plot.

df: dataframe object

condition: indicates the logical expression on the basis of which subsetting has to be done

Example:

R

plot(Murder ~ UrbanPop, data=subset(USArrests, Rape < 25))

Output: