qplot

Visualizing the mtcars dataset using ggplot’s qplot function

Importing necessary libraries

invisible(library(ggplot2))
invisible(library(datasets))

Modifying dataset before plotting

str(mtcars)

## 'data.frame':    32 obs. of  11 variables:
##  $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
##  $ cyl : num  6 6 4 6 8 6 8 4 4 6 ...
##  $ disp: num  160 160 108 258 360 ...
##  $ hp  : num  110 110 93 110 175 105 245 62 95 123 ...
##  $ drat: num  3.9 3.9 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 ...
##  $ wt  : num  2.62 2.88 2.32 3.21 3.44 ...
##  $ qsec: num  16.5 17 18.6 19.4 17 ...
##  $ vs  : num  0 0 1 1 0 1 0 1 1 1 ...
##  $ am  : num  1 1 1 0 0 0 0 0 0 0 ...
##  $ gear: num  4 4 4 3 3 3 3 4 4 4 ...
##  $ carb: num  4 4 1 1 2 1 4 2 2 4 ...

Converting cyl variable to factor

mtcars$cyl = factor(mtcars$cyl)

Plotting the mpg (Miles per gallon) against weight, subsetting by number of cylinders

qplot(mpg,wt,data = mtcars,color = cyl)

Histograms

Plotting a histogram to analyse the mpg (miles per gallon)

qplot(mpg,data= mtcars,fill = cyl,bins = 20)

geom loess function

Adding a geom to the plot

qplot(mpg,wt,data = mtcars,geom = c("point","smooth"))

## `geom_smooth()` using method = 'loess' and formula 'y ~ x'

Facets

Creating facets, which are essentially panels in ggplot, where plots are put in panels based on a factor variable

qplot(mpg,wt,data = mtcars, facets = .~cyl)

qplot(mpg,data= mtcars,facets = cyl~.,bins = 20)