Homework

library(ggplot2)

data(mtcars)
summary(mtcars)

##       mpg             cyl             disp             hp       
##  Min.   :10.40   Min.   :4.000   Min.   : 71.1   Min.   : 52.0  
##  1st Qu.:15.43   1st Qu.:4.000   1st Qu.:120.8   1st Qu.: 96.5  
##  Median :19.20   Median :6.000   Median :196.3   Median :123.0  
##  Mean   :20.09   Mean   :6.188   Mean   :230.7   Mean   :146.7  
##  3rd Qu.:22.80   3rd Qu.:8.000   3rd Qu.:326.0   3rd Qu.:180.0  
##  Max.   :33.90   Max.   :8.000   Max.   :472.0   Max.   :335.0  
##       drat             wt             qsec             vs        
##  Min.   :2.760   Min.   :1.513   Min.   :14.50   Min.   :0.0000  
##  1st Qu.:3.080   1st Qu.:2.581   1st Qu.:16.89   1st Qu.:0.0000  
##  Median :3.695   Median :3.325   Median :17.71   Median :0.0000  
##  Mean   :3.597   Mean   :3.217   Mean   :17.85   Mean   :0.4375  
##  3rd Qu.:3.920   3rd Qu.:3.610   3rd Qu.:18.90   3rd Qu.:1.0000  
##  Max.   :4.930   Max.   :5.424   Max.   :22.90   Max.   :1.0000  
##        am              gear            carb      
##  Min.   :0.0000   Min.   :3.000   Min.   :1.000  
##  1st Qu.:0.0000   1st Qu.:3.000   1st Qu.:2.000  
##  Median :0.0000   Median :4.000   Median :2.000  
##  Mean   :0.4062   Mean   :3.688   Mean   :2.812  
##  3rd Qu.:1.0000   3rd Qu.:4.000   3rd Qu.:4.000  
##  Max.   :1.0000   Max.   :5.000   Max.   :8.000

Create a pie chart showing the proportion of cars from the ‘mtcars’ data set that have different ‘carb’ values

Create a bar graph, that shows the number of each ‘gear’ type in ‘mtcars’.

ggplot(data = mtcars, aes(x = gear)) + 
  geom_bar(stat = "count")

Show a stacked bar graph of the number of each gear type and how they are further divided out by ‘cyl’

ggplot(mtcars, 
    aes(x = factor(cyl), fill = factor(gear))) +  
    xlab("Values of 'cyl'") +
    ylab("Values of 'count of gear'") +
    geom_bar(color="black")

Draw a sctter plot showing the relationship between ‘wt’ and ‘mpg’

ggplot(mtcars, aes(x = wt, y = mpg)) +
     xlab("wt") + ylab("mpg") +
     geom_point() +
     geom_line() +
     ggtitle("Relationship between 'wt' and 'mpg'") +
     stat_smooth(method = "loess", formula = y ~ x,     size=1, col = "red")

Design: Show relationship between ‘hp’ and ‘carb’ via line chart

p1 <- ggplot() + geom_line(aes(y = carb, x = hp, colour = "relationship"),data = mtcars, stat="identity")

p1

I used this graph to see the relationship between carb and hp. From the graph, we could conclude that the higher horse power is, the more carb it produces.