R从当前数据帧创建新数据帧

Question

我正在尝试计算 2014 年世界杯小组赛阶段的最佳净胜球。

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

这些是进球数最高的比赛，但现在我需要制作一个包含球队名称的新数据框，并且 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

您可以通过这种方式节省一些输入时间。您首先获得分数差异和获胜者。当结果显示 w 时，主场获胜。所以你根本不必查看分数。添加得分差异和获胜者后，您可以通过使用 max().

对数据进行子集化来对数据进行子集化

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

这是另一个不使用 ifelse 来创建 "winner" 列的选项。这是基于 row/column 索引。数字列索引是通过将结果列与其唯一元素 (match(football$result,..) 匹配而创建的，行索引只是 1:nrow(football)。将 "football" 数据集的 'home'、'away' 和 cbind 列与带有 NA 的附加列 'draw' 进行子集，以便 'd' 中的元素 "result" 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 library(data.table)

中的 chmatch 来加快 match

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

注意：我在 link

中使用了完整的数据集

R从当前数据帧创建新数据帧

R make new data frame from current one

r

dataframe