12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061 ``````library(stringr) library(dplyr) # Make a dataframe of input, with column 2 as the letter and column 3 as the number input <- readLines("input12.txt") %>% str_match("^(\\w)(\\d+)\$") %>% as.data.frame(stringsAsFactors = FALSE) names(input) <- c("Orig", "Arg", "Param") input %>% mutate( Param = as.numeric(Param), # Make number numeric type angChange = ifelse(Arg == "R", Param, ifelse(Arg == "L", -Param, 0)), # Calculate what each R/L does to the angle Angle = cumsum(angChange) %% 360, # Calculate running angle, within 0-359 # Calculate amount to move East, South at each line MovEast = ifelse(Arg == "E", Param, ifelse(Arg == "W", -Param, ifelse(Arg == "F", cos(Angle * pi / 180) * Param, 0))), MovSouth = ifelse(Arg == "S", Param, ifelse(Arg == "N", -Param, ifelse(Arg == "F", sin(Angle * pi / 180) * Param, 0))), # Running tally of position PosEast = cumsum(MovEast), PosSouth = cumsum(MovSouth) ) -> shipsLog # Calculate manhattin distance mandist <- abs(sum(shipsLog\$MovEast)) + abs(sum(shipsLog\$MovSouth)) # Drop stuff from previous dataframe that wont be used this time shipsLog %>% select(Orig:Angle) %>% mutate( # Calculate the east, south amount being specified by param value tPMovEast = ifelse(Arg == "E", Param, ifelse(Arg == "W", -Param, 0)), tPMovSouth = ifelse(Arg == "S", Param, ifelse(Arg == "N", -Param, 0)), # Convert to a rotating reference frame according to the angle PMovEast = ifelse(Angle == 0, tPMovEast, ifelse(Angle == 90, tPMovSouth, ifelse(Angle == 180, -tPMovEast, -tPMovSouth))), PMovSouth = ifelse(Angle == 0, tPMovSouth, ifelse(Angle == 90, -tPMovEast, ifelse(Angle == 180, -tPMovSouth, tPMovEast))), # Calculate running position of waypoint in rotated frame PREastPos = cumsum(PMovEast) + 10, PRSouthPos = cumsum(PMovSouth) - 1, # Return to original fixed reference frame PTEastPos = ifelse(Angle == 0, PREastPos, ifelse(Angle == 90, -PRSouthPos, ifelse(Angle == 180, -PREastPos, PRSouthPos))), PTSouthPos = ifelse(Angle == 0, PRSouthPos, ifelse(Angle == 90, PREastPos, ifelse(Angle == 180, -PRSouthPos, -PREastPos))), # Calculate movement of ship at each line ShipMoveEast = ifelse(Arg == "F", Param * PTEastPos, 0), ShipMoveSouth = ifelse(Arg == "F", Param * PTSouthPos, 0) ) -> shipsLog2 # Calculate manhattin distance mandist2 <- abs(sum(shipsLog2\$ShipMoveEast)) + abs(sum(shipsLog2\$ShipMoveSouth))``````