r - 通过数据帧循环函数,区分,然后在原始数据帧中按列组合
问题描述
我正在尝试使用包 ballr 从篮球参考中收集一些数据。我正在尝试使用 NBASeasonTeamByYear 函数来收集多个赛季球队的赛季结果。那就是我想要每个团队在 2017 年到 2020 年的数据,然后再将数据框组合成由会议分隔的 2 个更大的数据框。
我首先用每个团队的代码和会议制作了一个数据框
league_teams <- data.frame("team" = c("ATL", "BOS", "NJN", "CHA", "CHI", "CLE", "DAL", "DEN",
"DET", "GSW", "HOU", "IND", "LAC", "LAL", "MEM", "MIA",
"MIL", "MIN", "NOH", "NYK", "OKC", "ORL", "PHI", "PHO",
"POR", "SAC", "SAS", "TOR", "UTA", "WAS"),
"conference" = c("East", "East", "East", "East", "East", "East", "West",
"West", "East", "West", "West", "East", "West", "West",
"West", "East", "East", "West", "West", "East", "West",
"East", "East", "West", "West", "West", "West", "East",
"West", "East"))
league_teams$team <- as.character(league_teams$team)
league_teams$conference <- as.factor(league_teams$conference)
现在,我在编写循环时遇到了麻烦,该循环首先使用每个独特的团队使用他们的代码和我想要的年份,然后将它们组合在一起,无论年份如何,但在每个会议中。
我从这个开始
for (team in league_teams) {
team_2017 <- NBASeasonTeamByYear(team = team, 2017)
team_2017$season <- as.factor(2017)
team_2017$team <- as.factor(team)
}
后面几行说明我想为各自的年份添加 2 列,为各自的团队代码添加 1 列,但不仅是 2017 年,而且一直到 2020 年。虽然我在编写循环时遇到了麻烦,并且认为我使用 rbind稍后将它们组合起来,但我不确定如何这样做,并在我制作的原始数据框中通过会议进行区分。
解决方案
考虑在用户定义的方法中概括您的过程并使用expand.grid
(所有组合)和Map
(元素循环)传递参数:
nba_df_build <- function(yr, team, conf) {
# base::TRANSFORM OR dplyr::MUTATE
transform(NBASeasonTeamByYear(team = team, season = yr),
season = as.factor(yr),
team = as.factor(team),
conference = as.factor(conf))
}
params_df <- expand.grid(year = 2017:2020,
team = league_teams$team,
conference = league_teams$conference)
df_list <- Map(nba_df_build, params_df$year, params_df$team, params_df$conference)
final_df <- do.call(rbind, df_list)
#final_df <- dplyr::bind_rows(df_list)
对于数据帧的任何拆分:
# LIST OF TWO CONFERENCE DATA FRAMES
conference_dfs <- split(final_df, final_df$conference)
# LIST OF FOUR SEASON DATA FRAMES
season_dfs <- split(final_df, final_df$season)
# LIST OF THIRTY TEAM DATA FRAMES
team_dfs <- split(final_df, final_df$team)
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