by group performance.Rmd

---
title: 'by group performance #4655'
author: "Doris Amoakohene"
date: "`r Sys.Date()`"
output: html_document
---


```{r}

#https://github.com/Rdatatable/data.table/pull/4655

#closes
#https://github.com/Rdatatable/data.table/issues/4646

#https://github.com/Rdatatable/data.table/pull/4655/commits

#fixes by
#https://github.com/Rdatatable/data.table/pull/4655

```


```{r}
library(atime)
library(data.table)
library(ggplot2)
library(git2r)
```

```{r}
atime.list <- atime::atime_versions(
pkg.path="C:/Users/Doris Afriyie/data.table",
pkg.edit.fun=function(old.Package, new.Package, sha, new.pkg.path){
      pkg_find_replace <- function(glob, FIND, REPLACE){
        atime::glob_find_replace(file.path(new.pkg.path, glob), FIND, REPLACE)
      }
      Package_regex <- gsub(".", "_?", old.Package, fixed=TRUE)
      Package_ <- gsub(".", "_", old.Package, fixed=TRUE)
      new.Package_ <- paste0(Package_, "_", sha)
      pkg_find_replace(
        "DESCRIPTION", 
        paste0("Package:\\s+", old.Package),
        paste("Package:", new.Package))
      pkg_find_replace(
        file.path("src","Makevars.*in"),
        Package_regex,
        new.Package_)
      pkg_find_replace(
        file.path("R", "onLoad.R"),
        Package_regex,
        new.Package_)
      pkg_find_replace(
        file.path("R", "onLoad.R"),
        sprintf('packageVersion\\("%s"\\)', old.Package),
        sprintf('packageVersion\\("%s"\\)', new.Package))
      pkg_find_replace(
        file.path("src", "init.c"),
        paste0("R_init_", Package_regex),
        paste0("R_init_", gsub("[.]", "_", new.Package_)))
      pkg_find_replace(
        "NAMESPACE",
        sprintf('useDynLib\\("?%s"?', Package_regex),
        paste0('useDynLib(', new.Package_))
    },
  N=10^seq(3,8),
  setup={ 
    n <- 500L
    set.seed(123L)
    n_nested = 40L
    dt = data.table(id = seq_len(n),
                    value = replicate(n, data.table(val1 = sample(n_nested)), simplify = FALSE))
  },#https://github.com/Rdatatable/data.table/issues/4646

  expr=data.table:::`[.data.table`(dt[seq_len(.N), value[[1L]], by = id]
      ,dt[, value[[1L]], by = id]),
  "Before"="8e78a309f75e724ff6eda219b8f2ad172a01f8e4",#https://github.com/Rdatatable/data.table/pull/4655/commits/8e78a309f75e724ff6eda219b8f2ad172a01f8e4
  "Regression"="06c43b102f4b97ec91cb14a0c1631f771a9a0414", #https://github.com/Rdatatable/data.table/tree/06c43b102f4b97ec91cb14a0c1631f771a9a0414
  "Fixed"="ec041f78691f9f9495c0f25b78109cd3f5295f4f") #fixed:#https://github.com/Rdatatable/data.table/tree/ec041f78691f9f9495c0f25b78109cd3f5295f4f. for fixed.
```