Question

我有一个1314元素长的列表。每个元素都是一个由两行四列组成的数据框。

Game.ID         Team   Points    Victory
1 201210300CLE  CLE     94       0
2 201210300CLE  WAS     84       0

我想使用lapply函数来比较每个游戏中每个团队的积分，并将胜利团队的胜利更改为1。

我试图使用此功能：

test_vic <- lapply(all_games, function(x) {if (x[1,3] > x[2,3]) {x[1,4] = 1}})

但它产生的结果是一个列表1314个元素长，只有游戏ID和一个1或一个null，一个la：

$`201306200MIA`
[1] 1

$`201306160SAS`
NULL

如何修复代码以使每个数据框保持其形状。（我猜测解决null部分涉及if-else，但我需要弄清楚正确的语法。）

感谢。

Answer 1

尝试

lapply(all_games, function(x) {x$Victory[which.max(x$Points)] <- 1; x})

或另一种选择是使用list将data.table转换为rbindlist，然后进行转换

library(data.table)
rbindlist(all_games)[,Victory:= +(Points==max(Points)) ,Game.ID][]

数据

 all_games <- list(structure(list(Game.ID = c("201210300CLE", 
 "201210300CLE"
 ), Team = c("CLE", "WAS"), Points = c(94L, 84L), Victory = c(0L, 
 0L)), .Names = c("Game.ID", "Team", "Points", "Victory"),
 class =  "data.frame", row.names = c("1", 
 "2")), structure(list(Game.ID = c("201210300CME", "201210300CME"
 ), Team = c("CLE", "WAS"), Points = c(90, 92), Victory = c(0L, 
 0L)), .Names = c("Game.ID", "Team", "Points", "Victory"),
 row.names = c("1", "2"), class = "data.frame"))

Answer 2

您可以尝试dplyr：

library(dplyr)
all_games %>%
  bind_rows() %>%
  group_by(Game.ID) %>%
  mutate(Victory = row_number(Points)-1)

给出了：

#Source: local data frame [4 x 4]
#Groups: Game.ID
#
#       Game.ID Team Points Victory
#1 201210300CLE  CLE     94       1
#2 201210300CLE  WAS     84       0
#3 201210300CME  CLE     90       0
#4 201210300CME  WAS     92       1

比较数据帧列表中的行对

2 个答案:

数据