根据年份输入创建加权平均值和 3 年平均值

Question

我希望有人能帮我想出一个解决我的问题的方法。我有一个数据框，我希望根据现有数据框添加 2 组新值。

1. 加权平均值得出综合加权平均值，按统计数据（2014 = .4、2015 = .4 和 2016 = .2）乘以分组统计数据（HR、R、RBI、SB）
2. 3 年平均（与上面的想法相同，但只是最近 3 年的连续 3 年平均值）

我希望在季节列下标识新数据。

这是data.frame：

full_table_raw <- structure(list(playerID = c("abreujo02", "abreujo02", 
"abreujo02", "abreujo02", "abreujo02", "abreujo02", "abreujo02", 
"abreujo02", "abreujo02", "abreujo02", "abreujo02", "abreujo02", 
"arenano01", "arenano01", "arenano01", "arenano01", "arenano01", 
"arenano01", "arenano01", "arenano01", "arenano01", "arenano01", 
"arenano01", "arenano01", "blackch02", "blackch02", "blackch02", 
"blackch02", "blackch02", "blackch02", "blackch02", "blackch02", 
"blackch02", "blackch02", "blackch02", "blackch02"), season = c(2014L, 
2014L, 2014L, 2014L, 2015L, 2015L, 2015L, 2015L, 2016L, 2016L, 2016L, 
2016L, 2014L, 2014L, 2014L, 2014L, 2015L, 2015L, 2015L, 2015L, 
2016L, 2016L, 2016L, 2016L, 2014L, 2014L, 2014L, 2014L, 2015L, 
2015L, 2015L, 2015L, 2016L, 2016L, 2016L, 2016L), stat = c("HR", 
"R", "RBI", "SB", "HR", "R", "RBI", "SB", "HR", "R", "RBI", "SB", 
"HR", "R", "RBI", "SB", "HR", "R", "RBI", "SB", "HR", "R", "RBI", 
"SB", "HR", "R", "RBI", "SB", "HR", "R", "RBI", "SB", "HR", "R", 
"RBI", "SB"), points = c(3, 2, 3, 2, 2, 1, 2, 1, 1, 1, 2, 1, 
1, 1, 1, 1, 3, 3, 3, 2, 3, 3, 3, 2, 2, 3, 2, 3, 1, 2, 1, 3, 2, 
2, 1, 3), ranks = c(1, 2, 1, 2, 2, 3, 2, 3, 3, 3, 2, 3, 3, 3, 
3, 3, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 2, 1, 3, 2, 3, 1, 2, 2, 3, 
1), value = c(36, 80, 107, 3, 30, 88, 101, 0, 25, 67, 100, 0, 
18, 58, 61, 2, 42, 97, 130, 2, 41, 116, 133, 2, 19, 82, 72, 28, 
17, 93, 58, 43, 29, 111, 82, 17)), class = "data.frame", row.names = c(NA, 
-36L))

Answer 1

你可以这样做：

full_table_raw %>% 
  # add a new column with the weights to apply
  mutate(weight = ifelse(season == 2016, .2, .4)) %>%
  # group_by, and then compute your averages
  group_by(stat) %>% 
  summarize(
    average = sum(value) / 3,
    weighted_average = sum(value * weight))

这给了

# A tibble: 4 x 3
  stat  weighted_average average
  <chr>            <dbl>   <dbl>
1 HR                83.8    85.7
2 R                258     264  
3 RBI              275     281  
4 SB                35.0    32.3

如果您想将weighted_average 和average 作为列添加到初始数据框中，而不是计算摘要，则只需将summarize 替换为mutate

# A tibble: 36 x 9
# Groups:   stat [4]
   playerID  season stat  points ranks  value weight average weighted_average
   <chr>      <int> <chr>  <dbl> <dbl>  <dbl>  <dbl>   <dbl>            <dbl>
 1 abreujo02   2014 HR      3.00  1.00  36.0   0.400    85.7             83.8
 2 abreujo02   2014 R       2.00  2.00  80.0   0.400   264              258  
 3 abreujo02   2014 RBI     3.00  1.00 107     0.400   281              275  
 4 abreujo02   2014 SB      2.00  2.00   3.00  0.400    32.3             35.0
 5 abreujo02   2015 HR      2.00  2.00  30.0   0.400    85.7             83.8
 6 abreujo02   2015 R       1.00  3.00  88.0   0.400   264              258  
 7 abreujo02   2015 RBI     2.00  2.00 101     0.400   281              275  
...

请注意，我们可以使用最终的%>% select(-weight) 来删除我们添加的列weight