Question

为了跟上球队的最新状态，我想知道他们在最近的N场比赛中的表现。数据开始像这样：

HomeTeam   AwayTeam  Winner 

Liverpool  Chelsea   Home
Arsenal    Liverpool Away
Manchester Liverpool TBA

例如，我想在第3场比赛开始前的最近2场比赛中知道表格，结果数据帧应如下所示：

HomeTeam   AwayTeam  Winner HomeForm AwayForm

LiverPool  Chelsea   Home   NA       NA
Arsenal    Liverpool Away   0        1
Manchester Liverpool TBA    0        2

我同时研究了LAG和IF / ELSE函数，但似乎找不到能够动态查找结果的解决方案。

Answer 1

可能有一个更简单的破解方法，但是您可以尝试：

library(tidyverse)
library(zoo)

last_n_games <- 2

df <- df %>% rowid_to_column

Forms <- df %>%
  mutate(Winner = case_when(Winner == "Home" ~ HomeTeam, 
                            Winner == "Away" ~ AwayTeam,
                            TRUE ~ "TBA")
  ) %>% 
  gather(Team, name, HomeTeam:AwayTeam) %>%
  distinct(rowid, name, Winner) %>%
  group_by(name) %>%
  arrange(rowid) %>%
  mutate(
    HomeForm = +(Winner == name),
    HomeForm = rollapply(HomeForm, width = list(-(1:last_n_games)), sum, 
                              partial = TRUE, fill = NA, align = "right"),
    AwayForm = HomeForm
  ) %>%
  mutate_at(vars(contains("Form")), funs(ifelse(rowid != 1 & is.na(.), 0, .))) %>%
  distinct(rowid, name, HomeForm, AwayForm)

df %>%
  left_join(Forms %>% select(-AwayForm), by = c("rowid", "HomeTeam" = "name")) %>%
  left_join(Forms %>% select(-HomeForm), by = c("rowid", "AwayTeam" = "name")) %>%
  select(-rowid)

输出：

    HomeTeam  AwayTeam Winner HomeForm AwayForm
1  Liverpool   Chelsea   Home       NA       NA
2    Arsenal Liverpool   Away        0        1
3 Manchester Liverpool    TBA        0        2

哦，我忘了-这是假设您的数据框没有拼写错误（您有时确实将Liverpool设置为LiverPool吗？）。

如果这不仅是拼写错误，请告诉我们，我会改写代码。

通过R跟踪运动中的形式吗？

1 个答案: