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## Learn To Manipulate Data Frames Using The “mtcars” Dataset

### Task 1: Create a new column to find Displacement per Cylinder

Create a new variable (DisplacementPerCylinder), to calculate the total displacement per cylinder in cubic inches for each vehicle from the mtcars dataset.

# "str" allows you to display the internal structure of an R object
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 ...
##  $carb: num 4 4 1 1 2 1 4 2 2 4 ... # As a backup we can copy the original data frame into a new one to work with # That way if there is any issues we can go back my_mtcars <- mtcars # Calculate Displacement Per Cylinder by dividing the values (disp) and (cyl) my_mtcars$DisplacementPerCylinder <- my_mtcars$disp / my_mtcars$cyl

# Report a summary of the variable
summary(my_mtcars$DisplacementPerCylinder) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 17.77 26.92 34.48 35.03 43.19 59.00 ### Task 2: Create your own data frame Gather data from family & friends on the number of pets they have, the birth order they are in their family and the number of siblings. # Family/Friends ID friendID <- c(1, 2, 3, 4, 5) # Number of pets they have Pets <- c(4, 4, 2, 3, 1) # The birth order they are in their family Order <- c(1, 2, 2, 1, 1) # Number of Siblings Siblings <- c(2, 2, 1, 2, 0) # Binding the vectors into a data frame called myFriends myFriends <- data.frame(friendID, + Pets, + Order, + Siblings) # Command to report the structure of the data frame myFriends str(myFriends) ## 'data.frame': 5 obs. of 4 variables: ##$ friendID  : num  1 2 3 4 5
##  $X.Pets : num 4 4 2 3 1 ##$ X.Order   : num  1 2 2 1 1
##  $X.Siblings: num 2 2 1 2 0 # Rename the columns to get rid of the "x." in front of the names colnames(myFriends) <- c("FriendID", "Pets", "Order", "Siblings") str(myFriends) ## 'data.frame': 5 obs. of 4 variables: ##$ FriendID: num  1 2 3 4 5
##  $Pets : num 4 4 2 3 1 ##$ Order   : num  1 2 2 1 1
##  $Siblings: num 2 2 1 2 0 # Listing the values of the vector friendID from the data frame myFriends myFriends$FriendID
## [1] 1 2 3 4 5
# Listing the values of the vector Pets from the data frame myFriends
myFriends$Pets ## [1] 4 4 2 3 1 # Listing the values of the vector Order from the data frame myFriends myFriends$Order
## [1] 1 2 2 1 1
# Listing the values of the vector Siblings from the dataframe myFriends
myFriends\$Siblings
# [1] 2 2 1 2 0
# Report a summary of the dataframe
summary(myFriends)
##     FriendID      Pets         Order        Siblings
##  Min.   :1   Min.   :1.0   Min.   :1.0   Min.   :0.0
##  1st Qu.:2   1st Qu.:2.0   1st Qu.:1.0   1st Qu.:1.0
##  Median :3   Median :3.0   Median :1.0   Median :2.0
##  Mean   :3   Mean   :2.8   Mean   :1.4   Mean   :1.4
##  3rd Qu.:4   3rd Qu.:4.0   3rd Qu.:2.0   3rd Qu.:2.0
##  Max.   :5   Max.   :4.0   Max.   :2.0   Max.   :2.0

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