lpSolver script for fantasy football lineup optimization

Optimizer.R

runOptimizer <- function(excludes = list()) {
  
  #Read in dataset
  dataset<-read.csv("df_full.csv", stringsAsFactors = FALSE)
  
  # remove excludes from dataset
  
  if (length(excludes) > 1) {
    dataset <- anti_join(dataset, excludes, by="id")
  }

  #Change variables to appropriate types
  dataset$Pos <- as.factor(dataset$Pos)
 
  #### Prepare constraint matrix of zeros #####
  A <- matrix(0, nrow = 7, ncol = nrow(dataset))
  
  #Designate the positions that are equivalent to each other when generating the optimal lineup
  #There are 6 distinct positions and 1 constraint in which salary is < 50,000
  #I.e. A player with the position WR/RB/TE can fill the FLEX position
  #Add a "1" to all position that can fill that position slot
  
  #Set QB parameters
  j<-1
  i<-1
  for (i in 1:nrow(dataset)){
    if (dataset$Pos[i]=="QB")
      A[j,i]<-1
  }
  #RB
  j<-2
  i<-1
  for (i in 1:nrow(dataset)){
    if (dataset$Pos[i]=="RB")
      A[j,i]<-1
  }
  #WR
  j<-3
  i<-1
  for (i in 1:nrow(dataset)){
    if (dataset$Pos[i]=="WR")
      A[j,i]<-1
  }
  #TE
  j<-4
  i<-1
  for (i in 1:nrow(dataset)){
    if (dataset$Pos[i]=="TE")
      A[j,i]<-1
  }
  #FLEX
  j<-5
  i<-1
  for (i in 1:nrow(dataset)){
    if (dataset$Pos[i]=="RB" || 
        dataset$Pos[i]=="WR" || 
        dataset$Pos[i]== "TE")
      A[j,i]<-1
  }
  #DST
  j<-6
  i<-1
  for (i in 1:nrow(dataset)){
    if (dataset$Pos[i]=="DST") 
      A[j,i]<-1
  }
  
  A[7, ] <- dataset$Salary                # salary <= 50000
  
  # Prepare input for LP solver
  objective.in <- dataset$Proj_Points
  const.mat <- A
  const.dir <- c('==', '>=','>=', '>=','==','==', '<=')
  const.rhs <- c(1, 2, 3, 1, 7, 1, 50000)
  
  
  # Generate optimal lineup with lp solve
  require(lpSolve)
  sol <- lp(direction = "max", objective.in, # maximize objective function
            const.mat, const.dir, const.rhs,   # constraints
            all.bin = TRUE)                    # use binary variables only
  
  ### View the solution
  inds <- which(sol$solution == 1)
  sum(dataset$Salary[inds])
  
  solution<-dataset[inds, ]
  
  #Print players in optimal lineup
  solution
  
}