MLB runs per game (Lahman database)
| # load the package and data set "Teams" | |
| install.packages("Lahman") | |
| library("Lahman") | |
| data(Teams) | |
| # | |
| # | |
| # CREATE LEAGUE SUMMARY TABLES | |
| # ============================ | |
| # | |
| # select a sub-set of teams from 1901 [the establishment of the American League] forward to 2012 | |
| Teams_sub <- as.data.frame(subset (Teams, yearID > 1900)) | |
| # | |
| # calculate each team's average runs and runs allowed per game | |
| Teams_sub$RPG <- Teams_sub$R / Teams_sub$G | |
| Teams_sub$RAPG <- Teams_sub$RA / Teams_sub$G | |
| # | |
| # create new data frame with season totals for each league | |
| LG_RPG <- aggregate(cbind(R, RA, G) ~ yearID + lgID, data = Teams_sub, sum) | |
| # calculate league + season runs and runs allowed per game | |
| LG_RPG$LG_RPG <- LG_RPG$R / LG_RPG$G | |
| LG_RPG$LG_RAPG <- LG_RPG$RA / LG_RPG$G | |
| # | |
| # select a sub-set of teams from 1901 [the establishment of the American League] forward to 2012 | |
| # read the data into separate league tables | |
| ALseason <- (subset (LG_RPG, yearID > 1900 & lgID == "AL")) | |
| NLseason <- (subset (LG_RPG, yearID > 1900 & lgID == "NL")) | |
| # | |
| # +++++++++++++++++++++++++++++++++++++++++++++++++++ | |
| # | |
| # RUNS SCORED PER GAME | |
| # ==================== | |
| # | |
| # web references: | |
| # http://princeofslides.blogspot.ca/2011/05/sab-r-metrics-basics-of-loess.html | |
| # http://research.stowers-institute.org/efg/R/Statistics/loess.htm | |
| # | |
| # start with American League | |
| # create new object ALRunScore.LO for loess model | |
| ALRunScore.LO <- loess(ALseason$LG_RPG ~ ALseason$yearID) | |
| ALRunScore.LO.predict <- predict(ALRunScore.LO) | |
| # | |
| # create new objects RunScore.Lo.XX for loess models with "span" control | |
| ALRunScore.LO.25 <- loess(ALseason$LG_RPG ~ ALseason$yearID, span=0.25) | |
| ALRunScore.LO.25.predict <- predict(ALRunScore.LO.25) | |
| # | |
| ALRunScore.LO.5 <- loess(ALseason$LG_RPG ~ ALseason$yearID, span=0.5) | |
| ALRunScore.LO.5.predict <- predict(ALRunScore.LO.5) | |
| # | |
| # plot the data, add loess curve | |
| ylim <- c(3,6) | |
| plot(ALseason$LG_RPG ~ ALseason$yearID, | |
| ylim = ylim, | |
| main = "American League: runs per team per game, 1901-2012", | |
| xlab = "year", ylab = "runs per game") | |
| # loess predicted value line | |
| lines(ALseason$yearID, ALRunScore.LO.predict, lty="solid", col="red", lwd=2) | |
| lines(ALseason$yearID, ALRunScore.LO.25.predict, lty="dashed", col="blue", lwd=2) | |
| lines(ALseason$yearID, ALRunScore.LO.5.predict, lty="dotdash", col="black", lwd=2) | |
| legend(1980, 3.5, | |
| c("default", "span=0.25", "span=0.50"), | |
| lty=c("solid", "dashed", "dotdash"), | |
| col=c("red", "blue", "black"), | |
| lwd=c(2, 2, 2)) | |
| grid() | |
| # | |
| # NATIONAL LEAGUE | |
| # create new object RunScore.LO for loess model | |
| NLRunScore.LO <- loess(NLseason$LG_RPG ~ NLseason$yearID) | |
| NLRunScore.LO.predict <- predict(NLRunScore.LO) | |
| # | |
| # objects with span control in loess model | |
| NLRunScore.LO.25 <- loess(NLseason$LG_RPG ~ NLseason$yearID, span=0.25) | |
| NLRunScore.LO.25.predict <- predict(NLRunScore.LO.25) | |
| NLRunScore.LO.5 <- loess(NLseason$LG_RPG ~ NLseason$yearID, span=0.5) | |
| NLRunScore.LO.5.predict <- predict(NLRunScore.LO.5) | |
| # | |
| # plot the data, add loess curve | |
| ylim <- c(3,6) | |
| plot(NLseason$LG_RPG ~ NLseason$yearID, | |
| pch=2, col="black", | |
| ylim = ylim, | |
| main = "National League: runs per team per game, 1901-2012", | |
| xlab = "year", ylab = "runs per game") | |
| # loess predicted value line | |
| lines(NLseason$yearID, NLRunScore.LO.predict, lty="solid", col="blue", lwd=2) | |
| lines(NLseason$yearID, NLRunScore.LO.25.predict, lty="dashed", col="red", lwd=2) | |
| lines(NLseason$yearID, NLRunScore.LO.5.predict, lty="dotdash", col="black", lwd=2) | |
| # chart tidying | |
| legend(1980, 3.5, | |
| c("default", "span=0.25", "span=0.50"), | |
| lty=c("solid", "dashed", "dotdash"), | |
| col=c("blue", "red", "black"), | |
| lwd=c(2, 2, 2)) | |
| grid() | |
| # | |
| # | |
| # MULTI-PLOT -- MERGING AL AND NL RESULTS | |
| # plot individual years as lines | |
| ylim <- c(3,6) | |
| # start with AL line | |
| plot(ALseason$LG_RPG ~ ALseason$yearID, | |
| type="l", lty="solid", col="red", lwd=2, | |
| main = "Runs per team per game, 1901-2012", | |
| ylim = ylim, | |
| xlab = "year", ylab = "runs per game") | |
| # add NL line | |
| lines(NLseason$yearID, NLseason$LG_RPG, lty="solid", col="blue", lwd=2) | |
| # chart additions | |
| grid() | |
| legend(1900, 3.5, c("AL", "NL"), lty=c("solid", "solid"), col=c("red", "blue"), lwd=c(2, 2)) | |
| # | |
| # | |
| # plot loess curves (span=0.25) | |
| ylim <- c(3,6) | |
| # start with AL line | |
| plot(ALRunScore.LO.25.predict ~ ALseason$yearID, | |
| type="l", lty="solid", col="red", lwd=2, | |
| main = "Runs per team per game, 1901-2012", | |
| ylim = ylim, | |
| xlab = "year", ylab = "runs per game") | |
| # add NL line | |
| lines(NLseason$yearID, NLRunScore.LO.25.predict, lty="dashed", col="blue", lwd=2) | |
| # chart additions | |
| legend(1900, 3.5, | |
| c("AL (span=0.25)", "NL (span=0.25)"), | |
| lty=c("solid", "dashed"), | |
| col=c("red", "blue"), | |
| lwd=c(2, 2)) | |
| grid() | |
| # | |
| # | |
| # plot loess curves (span=0.50) | |
| ylim <- c(3,6) | |
| # start with AL line | |
| plot(ALRunScore.LO.5.predict ~ ALseason$yearID, | |
| type="l", lty="solid", col="red", lwd=2, | |
| main = "Runs per team per game, 1901-2012", | |
| ylim = ylim, | |
| xlab = "year", ylab = "runs per game") | |
| # add NL line | |
| lines(NLseason$yearID, NLRunScore.LO.5.predict, lty="dashed", col="blue", lwd=2) | |
| # chart additions | |
| legend(1900, 3.5, | |
| c("AL (span=0.50)", "NL (span=0.50)"), | |
| lty=c("solid", "dashed"), | |
| col=c("red", "blue"), | |
| lwd=c(2, 2)) | |
| grid() | |
| # | |
| # | |
| # | |
| # plot multiple loess curves (span=0.50 and 0.25) | |
| ylim <- c(3,6) | |
| # start with AL line | |
| plot(ALRunScore.LO.5.predict ~ ALseason$yearID, | |
| type="l", lty="solid", col="red", lwd=2, | |
| main = "Runs per team per game, 1901-2012", | |
| ylim = ylim, | |
| xlab = "year", ylab = "runs per game") | |
| # add NL line | |
| lines(NLseason$yearID, NLRunScore.LO.5.predict, lty="solid", col="blue", lwd=2) | |
| # add 0.25 lines | |
| lines(ALseason$yearID, ALRunScore.LO.25.predict, lty="dashed", col="red", lwd=2) | |
| lines(NLseason$yearID, NLRunScore.LO.25.predict, lty="dashed", col="blue", lwd=2) | |
| # chart additions | |
| legend(1900, 3.5, | |
| c("AL (span=0.50)", "NL (span=0.50)", "AL (span=0.25)", "NL (span=0.25)"), | |
| lty=c("solid", "solid", "dashed", "dashed"), | |
| col=c("red", "blue", "red", "blue"), | |
| lwd=c(2, 2, 2, 2)) | |
| grid() | |
| # | |
| # # # # # # # # # # # # # # # # # # | |
| # | |
| # calculate the difference between the two leagues | |
| # 1. absolute | |
| RunDiff <- (ALseason$LG_RPG - NLseason$LG_RPG) | |
| # 2. LOESS span=0.25 | |
| RunDiffLO <- (ALRunScore.LO.25.predict - NLRunScore.LO.25.predict) | |
| # | |
| # plot the LOESS difference | |
| ylim <- c(-1,1) | |
| plot(RunDiffLO ~ ALseason$yearID, | |
| type="l", lty="solid", col="red", lwd=2, | |
| main = "Run scoring trend: AL difference from NL, 1901-2012", | |
| ylim = ylim, | |
| xlab = "year", ylab = "runs per game") | |
| # add line at zero | |
| abline(h = 0, lty="dotdash") | |
| grid() | |
| # | |
| # plot each year difference as line, trend as line | |
| ylim <- c(-1,1.5) | |
| plot(RunDiffLO ~ ALseason$yearID, | |
| type="l", lty="solid", col="red", lwd=3, | |
| main = "Run scoring trend: AL difference from NL, 1901-2012", | |
| ylim = ylim, | |
| xlab = "year", ylab = "runs per game") | |
| # add RunDiff line | |
| lines(ALseason$yearID, RunDiff, lty="solid", col="black", lwd=1) | |
| # add line at zero | |
| abline(h = 0, lty="dotdash") | |
| grid() | |
| # | |
| # | |
| # plot each year difference as bar, trend as line | |
| ylim <- c(-1,1.5) | |
| plot(RunDiff ~ ALseason$yearID, | |
| type="h", lty="solid", col="blue", lwd=2, | |
| main = "Run scoring trend: AL difference from NL, 1901-2012", | |
| ylim = ylim, | |
| xlab = "year", ylab = "runs per game") | |
| # add RunDiff line | |
| lines(ALseason$yearID, RunDiffLO, lty="solid", col="black", lwd=2) | |
| # add line at zero | |
| abline(h = 0, lty="dotdash") | |
| # chart additions | |
| grid() | |
| legend(1900, 1.5, | |
| c("AL difference from NL: absolute", "AL difference from NL, LOESS (span=0.25)"), | |
| lty=c("solid", "solid"), | |
| col=c("blue", "black"), | |
| lwd=c(2, 2)) | |
| # | |
| # |
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