Load Required Packages

library(dplyr)
## 
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
## 
##     filter, lag
## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union
library(tidyverse)
## ── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
## ✔ forcats   1.0.1     ✔ readr     2.1.6
## ✔ ggplot2   4.0.1     ✔ stringr   1.6.0
## ✔ lubridate 1.9.4     ✔ tibble    3.3.0
## ✔ purrr     1.2.0     ✔ tidyr     1.3.2
## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag()    masks stats::lag()
## ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors

Load the Dataset

mtcars
##                      mpg cyl  disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710          22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
## Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
## Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
## Merc 240D           24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
## Merc 230            22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
## Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
## Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
## Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
## Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
## Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
## Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
## Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
## Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
## Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
## Honda Civic         30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
## Toyota Corolla      33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
## Toyota Corona       21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
## Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
## AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
## Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
## Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
## Fiat X1-9           27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
## Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
## Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
## Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
## Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
## Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8
## Volvo 142E          21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

Inspecting the Data

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 ...

Our rows represent a different style of car with some repeating cars. One of our variabes is currrently how many miles per gallon(mpg) each car gets. almost all variables are numeric but to name two would be horsepower (hp) and cylinders (cyl) ## Cleaning the Data

cars=mtcars %>%
  mutate(cyl=as.factor(cyl),am=as.factor(am))
str(cars)
## '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 : Factor w/ 3 levels "4","6","8": 2 2 1 2 3 2 3 1 1 2 ...
##  $ 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  : Factor w/ 2 levels "0","1": 2 2 2 1 1 1 1 1 1 1 ...
##  $ gear: num  4 4 4 3 3 3 3 4 4 4 ...
##  $ carb: num  4 4 1 1 2 1 4 2 2 4 ...

Selecting Relevant Variables

cars_clean=cars %>%
  select(mpg, hp, wt, cyl, am)

Filtering Observations

cars_hp=cars_clean %>%
  filter(hp>100)
cars_hp
##                      mpg  hp    wt cyl am
## Mazda RX4           21.0 110 2.620   6  1
## Mazda RX4 Wag       21.0 110 2.875   6  1
## Hornet 4 Drive      21.4 110 3.215   6  0
## Hornet Sportabout   18.7 175 3.440   8  0
## Valiant             18.1 105 3.460   6  0
## Duster 360          14.3 245 3.570   8  0
## Merc 280            19.2 123 3.440   6  0
## Merc 280C           17.8 123 3.440   6  0
## Merc 450SE          16.4 180 4.070   8  0
## Merc 450SL          17.3 180 3.730   8  0
## Merc 450SLC         15.2 180 3.780   8  0
## Cadillac Fleetwood  10.4 205 5.250   8  0
## Lincoln Continental 10.4 215 5.424   8  0
## Chrysler Imperial   14.7 230 5.345   8  0
## Dodge Challenger    15.5 150 3.520   8  0
## AMC Javelin         15.2 150 3.435   8  0
## Camaro Z28          13.3 245 3.840   8  0
## Pontiac Firebird    19.2 175 3.845   8  0
## Lotus Europa        30.4 113 1.513   4  1
## Ford Pantera L      15.8 264 3.170   8  1
## Ferrari Dino        19.7 175 2.770   6  1
## Maserati Bora       15.0 335 3.570   8  1
## Volvo 142E          21.4 109 2.780   4  1
nrow(cars_hp)
## [1] 23

Creating New Variables

cars_hp=cars_hp %>%
  mutate(power_to_weight=hp/wt)
cars_hp
##                      mpg  hp    wt cyl am power_to_weight
## Mazda RX4           21.0 110 2.620   6  1        41.98473
## Mazda RX4 Wag       21.0 110 2.875   6  1        38.26087
## Hornet 4 Drive      21.4 110 3.215   6  0        34.21462
## Hornet Sportabout   18.7 175 3.440   8  0        50.87209
## Valiant             18.1 105 3.460   6  0        30.34682
## Duster 360          14.3 245 3.570   8  0        68.62745
## Merc 280            19.2 123 3.440   6  0        35.75581
## Merc 280C           17.8 123 3.440   6  0        35.75581
## Merc 450SE          16.4 180 4.070   8  0        44.22604
## Merc 450SL          17.3 180 3.730   8  0        48.25737
## Merc 450SLC         15.2 180 3.780   8  0        47.61905
## Cadillac Fleetwood  10.4 205 5.250   8  0        39.04762
## Lincoln Continental 10.4 215 5.424   8  0        39.63864
## Chrysler Imperial   14.7 230 5.345   8  0        43.03087
## Dodge Challenger    15.5 150 3.520   8  0        42.61364
## AMC Javelin         15.2 150 3.435   8  0        43.66812
## Camaro Z28          13.3 245 3.840   8  0        63.80208
## Pontiac Firebird    19.2 175 3.845   8  0        45.51365
## Lotus Europa        30.4 113 1.513   4  1        74.68605
## Ford Pantera L      15.8 264 3.170   8  1        83.28076
## Ferrari Dino        19.7 175 2.770   6  1        63.17690
## Maserati Bora       15.0 335 3.570   8  1        93.83754
## Volvo 142E          21.4 109 2.780   4  1        39.20863

Grouping and Summarizing Data

summary_cyl=cars_hp %>%
  group_by(cyl) %>%
  summarise(mean_mpg=mean(mpg, na.rm=TRUE), mean_hp=mean(hp, na.rm=TRUE), count= n())
summary_cyl
## # A tibble: 3 × 4
##   cyl   mean_mpg mean_hp count
##   <fct>    <dbl>   <dbl> <int>
## 1 4         25.9    111      2
## 2 6         19.7    122.     7
## 3 8         15.1    209.    14
summary_transmission=cars_hp %>%
  group_by(am) %>%
  summarise(mean_mpg=mean(mpg, na.rm=TRUE), mean_power_to_weight_ratio=mean(power_to_weight, na.rm=TRUE))
summary_transmission
## # A tibble: 2 × 3
##   am    mean_mpg mean_power_to_weight_ratio
##   <fct>    <dbl>                      <dbl>
## 1 0         16.1                       44.6
## 2 1         20.6                       62.1

Interpreting the Summaries

Looking at our car groups efficiency for mpg, it would appear that 4 cylinder cars have the best fuel efficiency, as they have the best mean miles per gallon and the worst mean horsepower.

If we wanted to create a bar plot our summary cylinder table would be the better option as we could have each type of cylinder be its own chart, and compare things like mean horsepower or mean miles per gallon. The same is true if we wanted to make a box plot later on as the is simply more information was can use to make our plots in our summary cylinder.

Reflection

During the time in writing the code, I had a lot of trouble with the summarise function. it is much lengthier than the other functions and requires a bit more of knowledge about R language than the other, especially the “na.rm=TRUE” part as I had to look at resources to find out I needed to add that line of code. However something that does make more sense to me know is filtering data. I have no doubt that I can filter any data as the code is pretty straight forward for it.

Cleaning and summarizing data is important because it helps the reader focus on the important parts of the data that the author wants the reader to see. If an author does not clean their data, figures and tables will have too much information making it much harder to read and interpret.