Assignment week-3

library(Lahman)
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(magrittr)

#Q1
head(Pitching)

#Q2a
Q2a <- filter(Pitching, SHO>=12)
Q2a

#Q2b
Q2b <- filter(Pitching, SHO>=12 & ERA<=2)
Q2b

#Q3
Q3a <- slice(Pitching, 40:50)
Q3a

Q3b <- Pitching %>% slice(40:50) %>% select(playerID, SHO, ERA)
  #select(slice(Pitching, 40:50), playerID, SHO, ERA)
Q3b

Q3c <- Pitching %>% slice(40:50) %>% mutate(SOBB=SO/BB) %>% select(playerID, SHO, ERA, SOBB)
 #select(mutate(slice(Pitching, 40:50), SOBB=SO/BB), playerID, SHO, ERA, SOBB)
Q3c

Q3d <- bind_rows(Q3b, Q3c)
#bind_rows(select(slice(Pitching, 40:50), playerID, SHO, ERA), select(mutate(slice(Pitching, 40:50), SOBB=SO/BB), playerID, SHO, ERA, SOBB))
Q3d

#Bonus Question

Teams.new <- mutate(Teams, WP_BPT=R^2/(R^2+RA^2), WP=W/G, diff=WP_BPT-WP)
BQ <- Teams.new %>% filter(yearID>=2015 & yearID<=2019) %>% select(yearID, WP_BPT, WP, diff)                                                                                   
BQ

Teams2015 <- Teams.new %>% filter(yearID==2015) %>% select(yearID, WP_BPT, WP, diff)
Teams2015

Teams2016 <- Teams.new %>% filter(yearID==2016) %>% select(yearID, WP_BPT, WP, diff)
Teams2016