R 是否有方法根据观测名称从一个df读取/导入数据值到另一个df？

我有一个英国超级联赛球队评级的df和另一个完整赛季时间表的df。我希望能够将每支球队的评级作为一个变量附加到时间表中，这样我就可以得出每场比赛的概率。之后的一步是模拟整个赛季

我曾尝试编写一个if语句来匹配df_1到df_2的字符串，但我认为我的方法不对

我相信这对大多数人来说都是低级编码，我非常感谢你的帮助。我来这儿之前试过了。我真诚地感谢你

vec_1 <- c("team_a", "team_b", "team_c")
vec_2 <- c(1.7, 1.2, 0.8)
vec_3 <- c("team_d", "team_e", "team_f")
vec_4 <- c(0.3, 0.5, 0.4)

# df_1 ratings df

df_1 <- data_frame(team = vec_1, rating = vec_2)

 team   rating
  <chr>   <dbl>
1 team_a    1.7
2 team_b    1.2
3 team_c    0.8

# df_2 schedule df

df_2 <- data_frame(home_tm = vec_1, away_tm = vec_3)

  home_tm away_tm
  <chr>   <chr>  
1 team_a  team_d 
2 team_b  team_e 
3 team_c  team_f 

预期结果：

  home_tm away_tm home_tm_rat away_tm_rat
  <chr>   <chr>         <dbl>         <dbl>
1 team_a  team_d          1.7           0.3
2 team_b  team_e          1.2           0.5
3 team_c  team_f          0.8           0.4
......
......
......

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如上所述，可以检查dplyr的连接：

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类似于@liuminzhao，但我也建议您稍微考虑一下您的数据结构。如果将df_2中的所有球队都放在一列中，并用一个单独的列指示谁是主客场，事情就会变得更容易。阅读更多关于

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结帐加入从DPL可能重复的感谢一百万！谢谢大家！你好，我也会调查的。非常感谢。

df_2 %>% 
  left_join(df_1, by= c('home_tm' = 'team')) %>% 
  rename(home_tm_rat = rating) %>% 
  left_join(df_1, by = c('away_tm' = 'team')) %>% 
  rename(away_tm_rat = rating) 

# A tibble: 3 x 4
  home_tm away_tm home_tm_rat away_tm_rat
  <chr>   <chr>         <dbl>       <dbl>
1 team_a  team_d          1.7         0.3
2 team_b  team_e          1.2         0.5
3 team_c  team_f          0.8         0.4

library(tidyverse)

df_2 %>% 
  #gather the two columns of teams into a single column, using another column to indicate home/away
  gather(key = HomeAway, value = team) %>% 
  #join the team ratings
  left_join(df_1, by = c("team" = "team"))


# A tibble: 6 x 3
HomeAway team   rating
<chr>    <chr>   <dbl>
1 home_tm  team_a    1.7
2 home_tm  team_b    1.2
3 home_tm  team_c    0.8
4 away_tm  team_d   NA  
5 away_tm  team_e   NA  
6 away_tm  team_f   NA