From 06d65d51c055dc1197c5284147e2508384bd6bc2 Mon Sep 17 00:00:00 2001
From: Jim Hester <james.f.hester@gmail.com>
Date: Thu, 26 Jul 2012 09:55:16 -0400
Subject: [PATCH 1/2] Summarise sequentially

Summarise will now work sequentially, so you can use earlier summaries in
later summaries
---
 R/helper-summarise.r | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/R/helper-summarise.r b/R/helper-summarise.r
index f3c2eb04..4093723e 100644
--- a/R/helper-summarise.r
+++ b/R/helper-summarise.r
@@ -18,8 +18,7 @@
 #'  duration = max(year) - min(year), 
 #'  nteams = length(unique(team)))
 summarise <- function(.data, ...) {
-  cols <- eval(substitute(list(...)), .data, parent.frame())
-  
+  cols <- as.list(substitute(list(...))[-1])
   # ... not a named list, figure out names by deparsing call
   if(is.null(names(cols))) {
     missing_names <-  rep(TRUE, length(cols))
@@ -30,7 +29,15 @@ summarise <- function(.data, ...) {
     names <- unname(unlist(lapply(match.call(expand = FALSE)$`...`, deparse)))
     names(cols)[missing_names] <- names[missing_names]
   }
-
-  quickdf(cols)
+  cols <- cols[names(cols) != ""]
+  env <- new.env(parent=parent.frame())
+  for(name in names(.data)){
+    assign(name,.data[[name]],envir=env)
+  }
+  ret <- list()
+  for (col in names(cols)) {
+    ret[[col]] <- eval(cols[[col]], ret, env)
+  }
+  quickdf(ret)
 }
 summarize <- summarise

From e51fc374d2cf6ab472d8caa8d4238f5486ffb0b4 Mon Sep 17 00:00:00 2001
From: Jim Hester <james.f.hester@gmail.com>
Date: Wed, 8 Aug 2012 11:25:49 -0400
Subject: [PATCH 2/2] Convert data frame to list

Rather than copying the data frame to the environment, convert the data frame
to a list, so that the new values can be added to it.
---
 R/helper-summarise.r | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/R/helper-summarise.r b/R/helper-summarise.r
index 4093723e..476c9dfc 100644
--- a/R/helper-summarise.r
+++ b/R/helper-summarise.r
@@ -19,6 +19,7 @@
 #'  nteams = length(unique(team)))
 summarise <- function(.data, ...) {
   cols <- as.list(substitute(list(...))[-1])
+
   # ... not a named list, figure out names by deparsing call
   if(is.null(names(cols))) {
     missing_names <-  rep(TRUE, length(cols))
@@ -29,15 +30,10 @@ summarise <- function(.data, ...) {
     names <- unname(unlist(lapply(match.call(expand = FALSE)$`...`, deparse)))
     names(cols)[missing_names] <- names[missing_names]
   }
-  cols <- cols[names(cols) != ""]
-  env <- new.env(parent=parent.frame())
-  for(name in names(.data)){
-    assign(name,.data[[name]],envir=env)
-  }
-  ret <- list()
+  .data <- as.list(.data)
   for (col in names(cols)) {
-    ret[[col]] <- eval(cols[[col]], ret, env)
+    .data[[col]] <- eval(cols[[col]], .data, parent.frame())
   }
-  quickdf(ret)
+  quickdf(.data[names(cols)])
 }
 summarize <- summarise