加速R应用于数据帧

Question

我有一个赛马数据集。对于每条赛马记录，如果都没有丢失赛道价值，我想计算过去两年在相同场地，赛道和类似距离下的赛马获胜次数。我使用apply循环每一行，但是速度非常慢。如何加快循环速度？

日期：赛马年月日。地点：ST，HV。曲目：草皮，全天候追踪。距离：1200、1400、1600、1800等ind_win：0（马未赢得第一名），1（马未赢得第一名）。

structure(list(rdate = structure(c(17450, 17475, 17481, 17496, 
17510, 17517, 17532, 17566, 17593, 17615, 17629, 17657, 17667, 
17796, 17817, 17839, 17856, 17860, 17881, 17881, 17902, 17902
), class = "Date"), venue = c("HV", "ST", "ST", "ST", "ST", "ST", 
"ST", "ST", "ST", "ST", "ST", "ST", "HV", "ST", "ST", "ST", "HV", 
"ST", "ST", "ST", "ST", "ST"), track = c("TURF", "TURF", "TURF", 
"TURF", "TURF", "TURF", "TURF", "TURF", "TURF", "TURF", "TURF", 
"TURF", "TURF", "TURF", "TURF", "TURF", "TURF", "TURF", "TURF", 
"TURF", "TURF", "TURF"), horsenum = c("A366", "A366", "A366", 
"A366", "A366", "A366", "A366", "A366", "A366", "A366", "A366", 
"A366", "A366", "B440", "B440", "B440", "A366", "B440", "A366", 
"B440", "A366", "B440"), distance = c(1800L, 1800L, 1600L, 1600L, 
1800L, 1600L, 1800L, 1800L, 1800L, 1600L, 1800L, 2000L, 1800L, 
1200L, 1400L, 1400L, 1650L, 1400L, 1600L, 1400L, 1800L, 1400L
), ind_win = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 
0L, 0L, 0L, 0L, 0L, 1L, 0L, 0L, 0L, 1L)), row.names = c(NA, -22L
), class = "data.frame")

library(tidyverse)
library(lubridate)

HWinCountF <- function(df){
    if (!is.na(df["track"])) {
      tmp <- subset(jc.data, horsenum == df["horsenum"] & rdate < df["rdate"] & rdate > ymd(df["rdate"]) - years(2) &
                      venue == df["venue"] & track==df["track"] &  distance>=as.integer(df["distance"])-200 &
                      distance<=as.integer(df["distance"])+200)
      if (nrow(tmp) > 0) {
        return(nrow(tmp[tmp$ind_win == 1,]))
      } else {
        return(NA)
      }
    } else {
      return(NA)
    }
  }

  jc.data['h_win_count'] <- apply(jc.data, 1, HWinCountF)

Answer 1

我想计算过去两年中在相同场地，赛道和类似距离下获胜的马匹数量

由于这是直接汇总，请避免循环，并考虑将merge与数据帧的subset放在其自身上，因为您似乎需要相互比较观察值。然后运行aggregate以赢得马匹。下面以发布的数据示例运行。

# MERGE BY COMMON VARIABLES AND SUBSET RESULTS BY DATE AND DISTANCE
compare_df <- subset(merge(jc.data, jc.data, by=c("horsenum", "venue", "track")),
                     rdate.x < rdate.y &
                     rdate.x > lubridate::ymd(rdate.y) - lubridate::years(2) &
                     distance.x >= as.integer(distance.y) - 200 &
                     distance.x <= as.integer(distance.y) + 200 
              )

# SUM ind_win GROUPED BY COMMON VARIABLES
agg_df <- aggregate(cbind(h_win_count = ind_win.x) ~ horsenum + venue + track, 
                    data = compare_df, FUN=sum)

agg_df
#   horsenum venue track h_win_count
# 1     A366    HV  TURF           0
# 2     A366    ST  TURF           0
# 3     B440    ST  TURF           2