R中嵌套巨大列表的高效汇总统计

Efficient summary statistics of nested huge list in R

我正在 运行 进行模拟研究,我的结果存储在嵌套列表结构中。列表的第一层代表模型生成的不同超参数。第二层是相同模型的复制次数(换种子)。

在下面的示例中,我列出了一个由两个超参数(hyperpar1hyperpar2)控制的模型的输出,其中两个超参数都可以采用 2 个不同的值,从而导致 4 种不同的组合结果模型。此外,4 种可能的组合中的每一种都是 运行 两次(不同的种子),导致八种可能的组合(如下面 str(res, max = 2) 所示)。最后,从模型的每个可能迭代中恢复了两个性能指标(metric1metric2)。

我的问题是,在我的真实数据中,迭代次数(列表的第二级)很大(高达 10000),并且在某些情况下超参数数量的全阶乘高达 2000。因此退市过程变得相当缓慢

下面我列出了我当前的程序和我想要的输出,但同样,它相对较慢。特别是,有一个部分,当我取消列出所有内容时,我把它放在一个大的 data.frame 中,这需要很长时间,但我还没有以更快的方式解决这个问题。

res <-list(
  list(list(modeltype = "tree", time_iter = structure(0.7099, class = "difftime", units = "secs"),seed = 1, nobs = 75, hyperpar1 = 0.5, hyperpar2 = 0.5, metric1 = 0.4847, metric2 = 0.2576 ),
       list(modeltype = "tree", time_iter = structure(0.058 , class = "difftime", units = "secs"),seed = 2, nobs = 75, hyperpar1 = 0.5, hyperpar2 = 0.5, metric1 = 0.4013, metric2 = 0.2569 )), 
  list(list(modeltype = "tree", time_iter = structure(0.046 , class = "difftime", units = "secs"),seed = 1, nobs = 75, hyperpar1 = 0.8, hyperpar2 = 0.5, metric1 = 0.4755, metric2 = 0.2988 ), 
       list(modeltype = "tree", time_iter = structure(0.0474, class = "difftime", units = "secs"),seed = 2, nobs = 75, hyperpar1 = 0.8, hyperpar2 = 0.5, metric1 = 0.2413, metric2 = 0.2147 )), 
  list(list(modeltype = "tree", time_iter = structure(0.0502, class = "difftime", units = "secs"),seed = 1, nobs = 75, hyperpar1 = 0.5, hyperpar2 = 1  , metric1 = 0.7131, metric2 = 0.5024 ), 
       list(modeltype = "tree", time_iter = structure(2.9419, class = "difftime", units = "secs"),seed = 2, nobs = 75, hyperpar1 = 0.5, hyperpar2 = 1  , metric1 = 0.4254, metric2 = 0.2824 )), 
  list(list(modeltype = "tree", time_iter = structure(0.041 , class = "difftime", units = "secs"),seed = 1, nobs = 75, hyperpar1 = 0.8, hyperpar2 = 1  , metric1 = 0.6709, metric2 = 0.4092 ), 
       list(modeltype = "tree", time_iter = structure(0.0396, class = "difftime", units = "secs"),seed = 2, nobs = 75, hyperpar1 = 0.8, hyperpar2 = 1  , metric1 = 0.4585, metric2 = 0.4115 )))


hyperpar1   <-   c(0.5 , 0.8 ) 
hyperpar2   <-   c(0.5 , 1   )
expand.grid(hyperpar1 = hyperpar1, hyperpar2 = hyperpar2)

#   hyperpar1 hyperpar2
# 1       0.5       0.5
# 2       0.8       0.5
# 3       0.5       1.0
# 4       0.8       1.0

#List structure:
#The 4 elements represent the 4 combinations of the hyperparams
#Inside each of the 4 combinations of the hyperparams, 2 lists represent the 2 simulations (with different seeds)
str(res, max = 1)
#Finally, inside each of the final level (level=3) there is a list of 10 objects that are the results of each simulation
str(res, max = 2)

# List of 4
# $ :List of 2
# ..$ :List of 8
# ..$ :List of 8
# $ :List of 2
# ..$ :List of 8
# ..$ :List of 8
# $ :List of 2
# ..$ :List of 8
# ..$ :List of 8
# $ :List of 2
# ..$ :List of 8
# ..$ :List of 8

#e.g Fist iteration of first model 
t(res[[1]][[1]])
# modeltype time_iter seed nobs hyperpar1 hyperpar2 metric1 metric2
# [1,] "tree"    0.7099    1    75   0.5       0.5       0.4847  0.2576 


正在解析列表

在下面的代码中,我取消嵌套列表并将所有内容放入 data.frame。

#Unlist the nested structure of the list `res`
all_in_list <- lapply(1:length(res), function(i) {
     unlisting <- unlist(res[i],recursive = FALSE)
     to_df <- do.call(rbind, lapply(unlisting, as.data.frame))
     return(to_df)})

#Here is where averything get really really slow when the list is huge
all_in_df <- do.call(rbind, lapply(all_in_list, as.data.frame))

#   modeltype   time_iter seed nobs hyperpar1 hyperpar2 metric1 metric2
# 1      tree 0.7099 secs    1   75       0.5       0.5  0.4847  0.2576
# 2      tree 0.0580 secs    2   75       0.5       0.5  0.4013  0.2569
# 3      tree 0.0460 secs    1   75       0.8       0.5  0.4755  0.2988
# 4      tree 0.0474 secs    2   75       0.8       0.5  0.2413  0.2147
# 5      tree 0.0502 secs    1   75       0.5       1.0  0.7131  0.5024
# 6      tree 2.9419 secs    2   75       0.5       1.0  0.4254  0.2824
# 7      tree 0.0410 secs    1   75       0.8       1.0  0.6709  0.4092
# 8      tree 0.0396 secs    2   75       0.8       1.0  0.4585  0.4115

输出汇总统计

在下文中,我恢复了性能指标的均值和标准差,将它们的子集添加到每个 colname 以便稍后识别(绘图目的)。

#auxiliar function to compute the metrics at aggregate level. 
foo_summary <- function(df ,
                        metrics =c("time_iter","metric1", "metric2") ,
                        by = c("nobs","hyperpar1", "hyperpar2", "modeltype"),
                        summary_function =  mean)
{
#compute the aggregate metrics  
out <-  as.data.frame(aggregate(
    x = df[metrics],
    by = df[by],
    FUN = summary_function, 
    na.rm = TRUE))
#rename conviniently the metric computed
oldnames <- colnames(out[metrics])
names(out)[match(oldnames,names(out))] <- paste(colnames(out[metrics]), 
                                                as.character(substitute(summary_function)),
                                                sep = "_")
return(out)
}



df_mean <- foo_summary(df = all_in_df, 
            metrics =c("time_iter","metric1", "metric2"),
            by = c("nobs","hyperpar1", "hyperpar2", "modeltype"),
            summary_function =  mean)


df_sd <- foo_summary(df = all_in_df, 
            metrics =c("time_iter","metric1", "metric2"),
            by = c("nobs","hyperpar1", "hyperpar2", "modeltype"),
            summary_function =  sd)

final_df <- merge(df_mean,df_sd )

终于得到想要的输出了。

# nobs hyperpar1 hyperpar2 modeltype time_iter_mean metric1_mean metric2_mean time_iter_sd metric1_sd   metric2_sd
# 1   75       0.5       0.5      tree   0.38395 secs      0.44300      0.25725 0.4609629107 0.05897271 0.0004949747
# 2   75       0.5       1.0      tree   1.49605 secs      0.56925      0.39240 2.0447406792 0.20343462 0.1555634919
# 3   75       0.8       0.5      tree   0.04670 secs      0.35840      0.25675 0.0009899495 0.16560441 0.0594676803
# 4   75       0.8       1.0      tree   0.04030 secs      0.56470      0.41035 0.0009899495 0.15018948 0.0016263456

你可以试试 data.table:

library(data.table)

tmp = data.table(res)
tmp = tmp[, t(res[1]), by=1:nrow(tmp)]
tmp = tmp[, V1[[1]], by=1:nrow(tmp)]


g = function(x) list(mean = mean(x), sd = sd(x))
tmp[, unlist(lapply(.SD, g), recursive=FALSE)
    , .SDcols=hyperpar1:metric2,
    , by=.(nobs, hyperpar1, hyperpar2, modeltype)]

#>    nobs hyperpar1 hyperpar2 modeltype hyperpar1.mean hyperpar1.sd
#> 1:   75       0.5       0.5      tree            0.5            0
#> 2:   75       0.8       0.5      tree            0.8            0
#> 3:   75       0.5       1.0      tree            0.5            0
#> 4:   75       0.8       1.0      tree            0.8            0
#>    hyperpar2.mean hyperpar2.sd metric1.mean metric1.sd metric2.mean
#> 1:            0.5            0      0.44300 0.05897271      0.25725
#> 2:            0.5            0      0.35840 0.16560441      0.25675
#> 3:            1.0            0      0.56925 0.20343462      0.39240
#> 4:            1.0            0      0.56470 0.15018948      0.41035
#>      metric2.sd
#> 1: 0.0004949747
#> 2: 0.0594676803
#> 3: 0.1555634919
#> 4: 0.0016263456

此代码使用列表列的连续取消嵌套,这是我在本笔记本中描述的一种策略:http://arelbundock.com/posts/datatable_nesting/

使用dplyr::bind_rows(),直接将嵌套列表解嵌为data.frame,然后直接计算汇总统计:

library(dplyr)

bind_rows(res) %>%
  group_by(modeltype, nobs, hyperpar1, hyperpar2) %>%
  summarize(across(everything(), list(mean = mean, sd = sd)), .groups = "drop")

#> # A tibble: 4 x 12
#>   modeltype  nobs hyperpar1 hyperpar2 time_iter_mean time_iter_sd seed_mean
#>   <chr>     <dbl>     <dbl>     <dbl> <drtn>                <dbl>     <dbl>
#> 1 tree         75       0.5       0.5 0.38395 secs       0.461          1.5
#> 2 tree         75       0.5       1   1.49605 secs       2.04           1.5
#> 3 tree         75       0.8       0.5 0.04670 secs       0.000990       1.5
#> 4 tree         75       0.8       1   0.04030 secs       0.000990       1.5
#> # … with 5 more variables: seed_sd <dbl>, metric1_mean <dbl>, metric1_sd <dbl>,
#> #   metric2_mean <dbl>, metric2_sd <dbl>