Question

我试图计算2014年世界杯小组赛阶段的最佳进球差距。

football <- read.csv(
    file="http://pastebin.com/raw.php?i=iTXdPvGf", 
    header = TRUE, 
    strip.white = TRUE
)
football <- head(football,n=48L)
football[which(max(abs(football$home_score - football$away_score)) == abs(football$home_score - football$away_score)),]

结果

home home_continent home_score        away away_continent away_score result
4  Cameroon         Africa          0     Croatia         Europe          4      l
7     Spain         Europe          1 Netherlands         Europe          5      l
37  Germany

所以那些目标最高的游戏是不同的，但现在我需要创建一个具有团队名称的新数据框，abs(football$home_score-football$away_score)

Answer 1

 football$score_diff <- abs(football$home_score - football$away_score)
 football$winner <- ifelse(football$home_score > football$away_score, as.character(football$home), 
                      ifelse(football$result == "d", NA, as.character(football$away)))

Answer 2

你可以用这种方式保存一些打字。你首先获得分数差异和获胜者。当结果显示w时，home就是赢家。所以你根本不需要考虑分数。添加分数差异和获胜者后，您可以通过使用max()对数据进行分组来对数据进行分组。

mydf <- read.csv(file="http://pastebin.com/raw.php?i=iTXdPvGf", 
                 header = TRUE, strip.white = TRUE)
mydf <- head(mydf,n = 48L)

library(dplyr)

mutate(mydf, scorediff = abs(home_score - away_score),
             winner = ifelse(result == "w", as.character(home),
                         ifelse(result == "l", as.character(away), "draw"))) %>%
filter(scorediff == max(scorediff))

#      home home_continent home_score        away away_continent away_score result scorediff      winner
#1 Cameroon         Africa          0     Croatia         Europe          4      l         4     Croatia
#2    Spain         Europe          1 Netherlands         Europe          5      l         4 Netherlands
#3  Germany         Europe          4    Portugal         Europe          0      w         4     Germany

Answer 3

以下是另一个不使用ifelse创建“获胜者”列的选项。这基于行/列索引。通过将结果列与其唯一元素（match(football$result,..）匹配来创建数字列索引，行索引仅为1:nrow(football)。将“足球”数据集与“主页”，“离开”和cbind列进行子集，并使用附加列“绘制”使用NA，以便“结果”中的“d”元素更改为NA。

football$score_diff <- abs(football$home_score - football$away_score)
football$winner <-  cbind(football[c('home', 'away')],draw=NA)[ 
    cbind(1:nrow(football), match(football$result, c('w', 'l', 'd')))]

football[with(football, score_diff==max(score_diff)),]
#  home home_continent home_score    away away_continent away_score   result
 #60 Brazil  South America          1 Germany         Europe          7    l
 #   score_diff  winner
 #60          6 Germany

如果数据集非常大，您可以使用match中的chmatch来加快library(data.table)

library(data.table)
chmatch(as.character(football$result), c('w', 'l', 'd'))

注意：我在链接中使用了完整的数据集

R从当前的数据框中创建新的数据框

3 个答案: