Load the HomeRun_2014 data into R.

HomeRun <- read.csv("https://sullystats.github.io/Statistics6e/Data/HomeRun_2014.csv")
head(HomeRun,n=4)
##        Date           Hitter HitterTeam           Pitcher PitcherTeam INN
## 1 9/28/2014   Rizzo, Anthony        CHC       Fiers, Mike         MIL   1
## 2 9/28/2014 Bernadina, Roger        LAD      Scahill, Rob         COL   6
## 3 9/28/2014     Duvall, Adam         SF     Stauffer, Tim          SD   4
## 4 9/28/2014      Duda, Lucas        NYM Foltynewicz, Mike         HOU   8
##          Ballpark TrueDist SpeedOffBat Elev.Angle Horiz.Angle Apex Type
## 1     Miller Park      441       109.1       22.7        86.7   81   PL
## 2 Dodger Stadi...      424       113.2       27.7        62.3   98   ND
## 3       AT&T Park      423       103.6       31.9       112.9   98   ND
## 4      Citi Field      417       106.3       26.5        73.0   83   PL

If all the data in the data frame are quantitative, then use the following syntax:

cor(df_name)

However, if the data frame has some qualitative variables, you will need to select variables from the original data frame so it only contains the quantitative variables you wish to analyze.

Use the select( ) command to create a new data frame that is a subset of an existing data frame. This will allow you to find correlation coefficients by some qualitative variable. Let’s say we only want to find the correlation coefficient between TrueDist, SpeedOffBat,Elev.Angle, Horiz.Angle, and Apex.

library(mosaic)
df_HomeRun <- select(HomeRun,TrueDist, SpeedOffBat, Elev.Angle,  Horiz.Angle, Apex)  # Select certain variables from the data frame
cor(df_HomeRun)    # Find the correlation matrix of the new data frame
##                TrueDist SpeedOffBat Elev.Angle Horiz.Angle        Apex
## TrueDist     1.00000000   0.6869344 -0.3328835  0.10126718  0.08807084
## SpeedOffBat  0.68693436   1.0000000 -0.6023920  0.13127437 -0.29903646
## Elev.Angle  -0.33288347  -0.6023920  1.0000000 -0.01018030  0.86984450
## Horiz.Angle  0.10126718   0.1312744 -0.0101803  1.00000000  0.02517413
## Apex         0.08807084  -0.2990365  0.8698445  0.02517413  1.00000000