Problem set1

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

carb <- mtcars$carb
carb

##  [1] 4 4 1 1 2 1 4 2 2 4 4 3 3 3 4 4 4 1 2 1 1 2 2 4 2 1 2 2 4 6 8 2

carb.freq <- table(carb)
carb.freq

## carb
##  1  2  3  4  6  8 
##  7 10  3 10  1  1

pie(carb.freq)

slices <- c(carb.freq) 
slices

##  1  2  3  4  6  8 
##  7 10  3 10  1  1

labels <- c("carb of 1 is", "carb of 2 is", "carb of 3 is", "carb of 4 is", "carb of 6 is", "carb of 8 is")
labels

## [1] "carb of 1 is" "carb of 2 is" "carb of 3 is" "carb of 4 is"
## [5] "carb of 6 is" "carb of 8 is"

percentage <- round(slices/sum(slices)*100,2)
percentage

##     1     2     3     4     6     8 
## 21.88 31.25  9.38 31.25  3.12  3.12

labels <- paste(labels, percentage, "%")
labels

## [1] "carb of 1 is 21.88 %" "carb of 2 is 31.25 %" "carb of 3 is 9.38 %" 
## [4] "carb of 4 is 31.25 %" "carb of 6 is 3.12 %"  "carb of 8 is 3.12 %"

pie(slices,labels = labels, col=rainbow(length(labels)), main="Pie Chart of carbs")

The result shows that cars with carb(carburetors) of 2 and 4 have the most value (31.25%) while cars with carbs 6 and 8 have the least percentage of vales (3.12%)

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

gear <- mtcars$gear
gear

##  [1] 4 4 4 3 3 3 3 4 4 4 4 3 3 3 3 3 3 4 4 4 3 3 3 3 3 4 5 5 5 5 5 4

gear.freq <- table(gear)
gear.freq

## gear
##  3  4  5 
## 15 12  5

barplot(gear.freq, main="Gear Distribution",xlab="Number of Gears",ylab="Number of cars",col=rainbow(length(gear.freq)))

This graph shows that cars with 3 Gears have the highest distribution among all of them and is more than 12 which is 15 in its frequency table and cars with 4 gears is in next level of frequency ans cars with 5 gears are in last level and are less than 6.

3.Next show a stacked bar graph of the number of each gear type and how they are further divided out by cyl.

a <- table(mtcars$cyl, mtcars$gear)
a

##    
##      3  4  5
##   4  1  8  2
##   6  2  4  1
##   8 12  0  2

barplot(a, main="Distribution of Gears devided by cyl",names.arg=c("3 Gears", "4 Gears", "5   Gears"),
        cex.names =0.8, xlab="Number of gear", ylab="Number of Cars", col=c("green","red","blue"),legend = rownames(a))

This stacked bar shows that the majority of 3 gears cars have 8 cylinders while none of the 4 gear cars are 8 cylinders.It seems cars with 4 gears and 4 cylinders are 2 times more than cars with 4 gears and 6 cylinders. The propotion of 6 cylinder cars is the smalles for 5 gears cars.

4.Draw a scatter plot showing the relationship between wt and mpg.

plot(mtcars$wt,mtcars$mpg,main = "scatter plot of weight vs mpg",xlab = "car weight",ylab= "mile per gallon")

The graph shows that by increasing the wt (weight of the car) its mpg(Milage per gallon) is decreased.

5. Design a visualization of your choice using the data and write a brief summary about why you chose that visualization.

wt <- mtcars$wt
wt

##  [1] 2.620 2.875 2.320 3.215 3.440 3.460 3.570 3.190 3.150 3.440 3.440
## [12] 4.070 3.730 3.780 5.250 5.424 5.345 2.200 1.615 1.835 2.465 3.520
## [23] 3.435 3.840 3.845 1.935 2.140 1.513 3.170 2.770 3.570 2.780

hp <-mtcars$hp
hp

##  [1] 110 110  93 110 175 105 245  62  95 123 123 180 180 180 205 215 230
## [18]  66  52  65  97 150 150 245 175  66  91 113 264 175 335 109

a <- lm(formula = hp~wt,data=mtcars)
plot(hp~wt, ylab="Gross horsepower" , xlab="Car Weight")
abline(a , col="green")

Problem set1

Nazanin Yousefzadeh

January 20, 2018

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

The result shows that cars with carb(carburetors) of 2 and 4 have the most value (31.25%) while cars with carbs 6 and 8 have the least percentage of vales (3.12%)

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

This graph shows that cars with 3 Gears have the highest distribution among all of them and is more than 12 which is 15 in its frequency table and cars with 4 gears is in next level of frequency ans cars with 5 gears are in last level and are less than 6.

3.Next show a stacked bar graph of the number of each gear type and how they are further divided out by cyl.

This stacked bar shows that the majority of 3 gears cars have 8 cylinders while none of the 4 gear cars are 8 cylinders.It seems cars with 4 gears and 4 cylinders are 2 times more than cars with 4 gears and 6 cylinders. The propotion of 6 cylinder cars is the smalles for 5 gears cars.

4.Draw a scatter plot showing the relationship between wt and mpg.

The graph shows that by increasing the wt (weight of the car) its mpg(Milage per gallon) is decreased.

5. Design a visualization of your choice using the data and write a brief summary about why you chose that visualization.

This plot shows with increasing the car weight, the horsepower of car will increase as well and vise versa.