Question

我正在尝试创建一个仅显示获胜队伍的新列。

以下是一些示例数据：

results <- data.frame(
  home_team = c("Scotland", "England", "Scotland", "England", "Scotland", "Scotland",
                "England", "Wales", "Scotland", "Scotland", "England"),
  away_team = c("England", "Scotland", "England", "Scotland", "England", "Wales",
                "Scotland", "Scotland", "England", "Wales", "Wales"),
  home_score = c(0, 4, 2, 2, 3, 4, 1, 0, 7, 9, 2),
  away_score = c(0, 2, 1, 2, 0, 0, 3, 2, 2, 0, 1),
  stringsAsFactors = FALSE
)

这是到目前为止的代码：

results <- intl.football.results
first6home <- head(results$home_team)
first6away <- head(results$away_team)
homescore <- (results$home_score)
awayscore <- (results$away_score)

data.frame('winning_team' = 0, results)

for (i in 1:length(results)){
  if(homescore[i] > awayscore[i]){
    homewins <- print("home wins")
  }else if(homescore[i] == awayscore[i]){
    draw <- print("draw")
  }else{
    awaywins <- print("away team wins")
  }
}

我认为我需要以某种方式纠正home_team的“ homewins”。我能想到的最好方法是找到“ homewins”的行号，然后选择home_team所在的行。但是，如果data.frame有30,000+行，我该怎么办？抱歉，这听起来很基础，但我正在尝试！

谢谢大家的回应，我一定会实践的。最后一件事，如果我想打印出获奖国家/地区列而不是“回家，离开或抽奖”怎么办？

Answer 1

dplyr中的case_when函数可能是解决此问题的好方法。似乎与您上面要执行的操作非常接近，因此希望它非常直观。

文档和更多示例： https://dplyr.tidyverse.org/reference/case_when.html

我要从相应行中传递获胜团队的名称作为case_when采取的操作，但是您可以传递一个字符串，例如如果您想要的是结果，就像我在抽奖游戏中所做的那样，“主场胜利”。

library(tidyverse)


d <- tibble(
        home_team = c('Scotland', 'England', 'Scotland', 'England', 
                'Scotland', 'Scotland', 'England', 'Wales'), 
        away_team = c('England', 'Scotland', 'England', 'Scotland', 
                'England', 'Wales', 'Scotland', 'Scotland'), 
        home_score = c(0, 4, 2, 2, 3, 4, 1, 0), 
        away_score = c(0, 2, 1, 2, 0, 0, 3, 2))

d %>% 
        mutate(winner = case_when(
                home_score > away_score ~ home_team, 
                away_score > home_score ~ away_team, 
                away_score == home_score ~ 'Drawn Game'))

Answer 2

一种解决方案是使用data.table包来处理您的数据。使用此软件包，解决您的问题的方法是（假设平局将导致“ T”，客场获胜“ A”而主场获胜“ H”）

library(data.table)

setDT(results)
results[
    , w_team := "T"][
    home_score > away_score, w_team := "H"][
    home_score < away_score, w_team := "A"]

Answer 3

基本R：

results$who_wins <- with(results,
  ifelse(home_score > away_score, "home wins",
         ifelse(home_score < away_score, "away wins", "draw")))
results
#    home_team away_team home_score away_score  who_wins
# 1   Scotland   England          0          0      draw
# 2    England  Scotland          4          2 home wins
# 3   Scotland   England          2          1 home wins
# 4    England  Scotland          2          2      draw
# 5   Scotland   England          3          0 home wins
# 6   Scotland     Wales          4          0 home wins
# 7    England  Scotland          1          3 away wins
# 8      Wales  Scotland          0          2 away wins
# 9   Scotland   England          7          2 home wins
# 10  Scotland     Wales          9          0 home wins
# 11   England     Wales          2          1 home wins

Answer 4

只是为了好玩，您还可以通过计算得分差异的符号，然后匹配查找向量来实现此目的

lookup <- c('home' = 1, 'away' = -1, 'draw' = 0)
results$winner <- 
  with(results, names(lookup)[match(sign(home_score - away_score), lookup)])

results
#    home_team away_team home_score away_score winner
# 1   Scotland   England          0          0   draw
# 2    England  Scotland          4          2   home
# 3   Scotland   England          2          1   home
# 4    England  Scotland          2          2   draw
# 5   Scotland   England          3          0   home
# 6   Scotland     Wales          4          0   home
# 7    England  Scotland          1          3   away
# 8      Wales  Scotland          0          2   away
# 9   Scotland   England          7          2   home
# 10  Scotland     Wales          9          0   home
# 11   England     Wales          2          1   home

创建一个仅显示获胜团队的新列

4 个答案: