我通过玩弄来学习 R，我开始认为我在滥用 tapply 功能。是否有更好的方法来执行以下某些操作？当然，它们有效，但随着它们变得越来越复杂，我想知道我是否会失去更好的选择。我在这里寻找一些批评：
tapply(var1, list(fac1, fac2), mean, na.rm=T)
tapply(var1, fac1, sum, na.rm=T) / tapply(var2, fac1, sum, na.rm=T)
cumsum(tapply(var1, fac1, sum, na.rm=T)) / sum(var1)
更新：这是一些示例数据...
var1 var2 fac1 fac2
1 NA 275.54 10 (266,326]
2 NA 565.89 10 (552,818]
3 NA 815.41 6 (552,818]
4 NA 281.77 6 (266,326]
5 NA 640.24 NA (552,818]
6 NA 78.42 NA [78.4,266]
7 NA 1027.06 NA (818,1.55e+03]
8 NA 355.20 NA (326,552]
9 NA 464.52 NA (326,552]
10 NA 1397.11 10 (818,1.55e+03]
11 NA 229.82 NA [78.4,266]
12 NA 542.77 NA (326,552]
13 NA 829.32 NA (818,1.55e+03]
14 NA 284.78 NA (266,326]
15 NA 194.97 10 [78.4,266]
16 NA 672.55 8 (552,818]
17 NA 348.01 10 (326,552]
18 NA 1550.79 9 (818,1.55e+03]
19 101.98 101.98 4 [78.4,266]
20 NA 292.80 6 (266,326]
更新数据转储：
structure(list(var1 = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
NA, NA, NA, NA, NA, NA, NA, NA, 101.98, NA), var2 = c(275.54,
565.89, 815.41, 281.77, 640.24, 78.42, 1027.06, 355.2, 464.52,
1397.11, 229.82, 542.77, 829.32, 284.78, 194.97, 672.55, 348.01,
1550.79, 101.98, 292.8), fac1 = c(10L, 10L, 6L, 6L, NA, NA, NA,
NA, NA, 10L, NA, NA, NA, NA, 10L, 8L, 10L, 9L, 4L, 6L), fac2 = structure(c(2L,
4L, 4L, 2L, 4L, 1L, 5L, 3L, 3L, 5L, 1L, 3L, 5L, 2L, 1L, 4L, 3L,
5L, 1L, 2L), .Label = c("[78.4,266]", "(266,326]", "(326,552]",
"(552,818]", "(818,1.55e+03]"), class = "factor")), .Names = c("var1",
"var2", "fac1", "fac2"), row.names = c(NA, -20L), class = "data.frame")