计算平均差值

Question

我有以下 data.table:-

set.seed(1234332)
kks <- data.table(name = c("a", "a", "b", "b", "b", "d", "d", "d", "e", "f", "f", "f", "f"),
                  year = c(2012, 2013, 2011, 2012, 2013, 2011, 2012, 2013, 2014, 2011, 2012, 2013, 2014),
                  loc = c(1, 1, 1, 1, 1, 2, 2, 2, 3, 2, 2, 2, 2),
                  value1 = runif(13),
                  value2 = rnorm(13),
                  value3 = runif(13))

我想计算变量 value1、value2 和 value3 的平均差值。但我希望根据列 loc 而不是 name 计算平均值。因此，应根据相同的loc值计算平均值。

我或许可以使用 for 循环来完成此操作。但我想知道使用 data.table.

是否有更简单的方法

提前致谢。

Answer 1

正如评论中所指出的，我不确定“根据 loc 列”是什么意思。如果您指的是 by 组，那么我会执行以下操作（也不确定，您是否要保留旧列）：

library(data.table)

col_nms <- paste0("value", 1:3)
new_col_nms <- paste0("diff_", col_nms)

kks[,
    (new_col_nms) := lapply(.SD, function(x) x - mean(x)),
    by = loc,
    .SDcols = col_nms][]

#>     name year loc    value1       value2     value3 diff_value1 diff_value2
#>  1:    a 2012   1 0.5525851 -1.216676578 0.40580256 -0.18364096 -1.49987982
#>  2:    a 2013   1 0.4099640  0.574428779 0.36695270 -0.32626208  0.29122553
#>  3:    b 2011   1 0.9936533  2.104311096 0.81294598  0.25742724  1.82110785
#>  4:    b 2012   1 0.8424899 -0.036993187 0.56436515  0.10626381 -0.32019643
#>  5:    b 2013   1 0.8824381 -0.009053885 0.62298286  0.14621198 -0.29225713
#>  6:    d 2011   2 0.1191904 -1.072735734 0.63039403 -0.39648257 -0.67081978
#>  7:    d 2012   2 0.7608226  0.229140684 0.34979251  0.24514966  0.63105663
#>  8:    d 2013   2 0.6963069 -0.570565439 0.59228905  0.18063397 -0.16864949
#>  9:    e 2014   3 0.8863696  0.879948680 0.44716966  0.00000000  0.00000000
#> 10:    f 2011   2 0.5611566 -0.684572180 0.05950426  0.04548364 -0.28265623
#> 11:    f 2012   2 0.9437519 -0.499744731 0.10843697  0.42807896 -0.09782878
#> 12:    f 2013   2 0.4148588  0.541616469 0.72578654 -0.10081415  0.94353242
#> 13:    f 2014   2 0.1136235 -0.756550716 0.94052853 -0.40204951 -0.35463477
#>      diff_value3
#>  1: -0.148807293
#>  2: -0.187657152
#>  3:  0.258336131
#>  4:  0.009755303
#>  5:  0.068373010
#>  6:  0.143718043
#>  7: -0.136883476
#>  8:  0.105613065
#>  9:  0.000000000
#> 10: -0.427171722
#> 11: -0.378239014
#> 12:  0.239110555
#> 13:  0.453852549

^{由 reprex package (v2.0.1)}

于 2022-04-07 创建

计算平均差值

Calculate mean difference values

r

data.table