groupby with dogroups (R expression) performance regression #4200.Rmd

---
title: "groupby with dogroups 4200"
author: "Doris Amoakohene"
date: '`r Sys.Date()`'
output: html_document
---


https://github.com/Rdatatable/data.table/issues/4200 -- Discusses Regression
https://github.com/Rdatatable/data.table/issues/4200#issuecomment-578629820
https://github.com/Rdatatable/data.table/pull/4558 --- Fixes Regression

```{r}

library(atime)
library(data.table)

```

```{r}
  tdir <- tempfile()
  dir.create(tdir)
  git2r::clone("https://github.com/Rdatatable/data.table", tdir)
  
```


```{r}

atime.list.4200 <- atime::atime_versions(
pkg.path=tdir,
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(1,20),
  setup={ 
    set.seed(108)
    d <- data.table(
      id3 = sample(c(seq.int(N*0.9), sample(N*0.9, N*0.1, TRUE))),
      v1 = sample(5L, N, TRUE),
      v2 = sample(5L, N, TRUE))
  },
  expr=data.table:::`[.data.table`(d[, max(v1)-min(v2), by = id3]),
"Before"="20d485587d258f7d820e5e4cc0089dd6bda6a141",
  "Regression"="15f0598b9828d3af2eb8ddc9b38e0356f42afe4f", 
  "Fixed"="ba32f3cba38ec270587e395f6e6c26a80be36be6") 
```


```{r}
plot(atime.list.4200)+
  labs(title = "groupby with dogroups (R expression) performance regression")

png("atime.list.4200.png")
plot(atime.list.4200)+
  labs(title = "groupby with dogroups (R expression) performance regression")
dev.off()

```