Hi all,
After reading this interesting discussion I delved a bit deeper into the
subject matter. The following snippet of code (see the end of my mail)
compares three ways of performing this task, using ddply, ave and one
yet unmentioned option: data.table (a package). The piece of code
Dear Caroline,
Here is a faster and more elegant solution.
n - 1
exampledata - data.frame(orderID = sample(floor(n / 5), n, replace = TRUE),
itemPrice = rpois(n, 10))
library(plyr)
system.time({
+ ddply(exampledata, .(orderID), function(x){
+ data.frame(itemPrice =
On Aug 3, 2011, at 9:25 AM, Caroline Faisst wrote:
Hello there,
Im computing the total value of an order from the price of the
order items
using a for loop and the ifelse function.
Ouch. Schools really should stop teaching SAS and BASIC as a first
language.
I do this on a
On Aug 3, 2011, at 9:59 AM, ONKELINX, Thierry wrote:
Dear Caroline,
Here is a faster and more elegant solution.
n - 1
exampledata - data.frame(orderID = sample(floor(n / 5), n, replace
= TRUE), itemPrice = rpois(n, 10))
library(plyr)
system.time({
+ ddply(exampledata,
This takes about 2 secs for 1M rows:
n - 100
exampledata - data.frame(orderID = sample(floor(n / 5), n, replace = TRUE),
itemPrice = rpois(n, 10))
require(data.table)
# convert to data.table
ed.dt - data.table(exampledata)
system.time(result - ed.dt[
+ ,
On Aug 3, 2011, at 12:20 PM, jim holtman wrote:
This takes about 2 secs for 1M rows:
n - 100
exampledata - data.frame(orderID = sample(floor(n / 5), n, replace
= TRUE), itemPrice = rpois(n, 10))
require(data.table)
# convert to data.table
ed.dt - data.table(exampledata)
On Aug 3, 2011, at 2:01 PM, Ken wrote:
Hello,
Perhaps transpose the table attach(as.data.frame(t(data))) and use
ColSums() function with order id as header.
-Ken Hutchison
Got any code? The OP offered a reproducible example, after all.
--
David.
On Aug 3, 2554 BE, at 1:12
Sorry about the lack of code, but using Davids example, would:
tapply(itemPrice, INDEX=orderID, FUN=sum)
work?
-Ken Hutchison
On Aug 3, 2554 BE, at 2:09 PM, David Winsemius dwinsem...@comcast.net wrote:
On Aug 3, 2011, at 2:01 PM, Ken wrote:
Hello,
Perhaps transpose the table
Hello,
Perhaps transpose the table attach(as.data.frame(t(data))) and use ColSums()
function with order id as header.
-Ken Hutchison
On Aug 3, 2554 BE, at 1:12 PM, David Winsemius dwinsem...@comcast.net wrote:
On Aug 3, 2011, at 12:20 PM, jim holtman wrote:
This takes
On Aug 3, 2011, at 3:05 PM, Ken wrote:
Sorry about the lack of code, but using Davids example, would:
tapply(itemPrice, INDEX=orderID, FUN=sum)
work?
Doesn't do the cumulative sums or the assignment into column of the
same data.frame. That's why I used ave, because it keeps the sequence
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