-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of arun
Sent: Friday, October 19, 2012 7:49 PM
To: Flavio Barros
Cc: R help; ramoss
Subject: Re: [R] Creating a new by variable in a dataframe
HI,
Without using "ifelse()" on the same example dataset.
d <- data.frame(stringsAsFactors = FALSE, transaction = c("T01", "T02",
"T03", "T04", "T05", "T06", "T07", "T08", "T09", "T10"),date =
c("2012-10-19", "2012-10-19", "2012-10-19", "2012-10-19", "2012-10-22",
"2012-10-23", "2012-10-23", "2012-10-23", "2012-10-23", "2012-10-23"),time
= c("08:00", "09:00", "10:00", "11:00", "12:00", "13:00", "14:00", "15:00",
"16:00", "17:00"))
d$date <- as.Date(d$date,format="%Y-%m-%d")
d$time<-strptime(d$time,format="%H:%M")$hour
d$flag<-unlist(rbind(lapply(split(d,d$date),function(x) x[3]==max(x[3]))))
d$datetime<-as.POSIXct(paste(d$date,d$time," "),format="%Y-%m-%d %H")
d1<-d[,c(1,5,4)]
?d1
#?? transaction??????????? datetime? flag
#1????????? T01 2012-10-19 08:00:00 FALSE
#2????????? T02 2012-10-19 09:00:00 FALSE
#3????????? T03 2012-10-19 10:00:00 FALSE
#4????????? T04 2012-10-19 11:00:00? TRUE
#5????????? T05 2012-10-22 12:00:00? TRUE
#6????????? T06 2012-10-23 13:00:00 FALSE
#7????????? T07 2012-10-23 14:00:00 FALSE
#8????????? T08 2012-10-23 15:00:00 FALSE
#9????????? T09 2012-10-23 16:00:00 FALSE
#10???????? T10 2012-10-23 17:00:00? TRUE
str(d1)
#'data.frame':??? 10 obs. of? 3 variables:
# $ transaction: chr? "T01" "T02" "T03" "T04" ...
# $ datetime?? : POSIXct, format: "2012-10-19 08:00:00" "2012-10-19 09:00:00" ...
# $ flag?????? : logi? FALSE FALSE FALSE TRUE TRUE FALSE ...
A.K.
----- Original Message -----
From: Flavio Barros <flaviomargarito at gmail.com>
To: William Dunlap <wdunlap at tibco.com>
Cc: "r-help at r-project.org" <r-help at r-project.org>; ramoss
<ramine.mossadegh at finra.org>
Sent: Friday, October 19, 2012 4:24 PM
Subject: Re: [R] Creating a new by variable in a dataframe
I think i have a better solution
*## Example data.frame*
d <- data.frame(stringsAsFactors = FALSE, transaction = c("T01", "T02",
"T03", "T04", "T05", "T06", "T07", "T08", "T09", "T10"),date =
c("2012-10-19", "2012-10-19", "2012-10-19", "2012-10-19", "2012-10-22",
"2012-10-23", "2012-10-23", "2012-10-23", "2012-10-23", "2012-10-23"),time
= c("08:00", "09:00", "10:00", "11:00", "12:00", "13:00", "14:00", "15:00",
"16:00", "17:00"))
*## As date tranfomation*
d$date <- as.Date(d$date)
d$time <- strptime(d$time, format='%H')
library(reshape)
*## Create factor to split the data*
fdate <- factor(format(d$date, '%D'))
*## Create a list with logical TRUE when is the last transaction*
ex <- sapply(split(d, fdate), function(x)
ifelse(as.numeric(x[,'time'])==max(as.numeric(x[,'time'])),T,F))
*## Coerce to logical vector*
flag <- unlist(rbind(ex))
*## With reshape we have the transform function e can add the flag column *
d <- transform(d, flag = flag)
On Fri, Oct 19, 2012 at 3:51 PM, William Dunlap <wdunlap at tibco.com> wrote:
Suppose your data frame is
d <- data.frame(
? ? ? stringsAsFactors = FALSE,
? ? ? transaction = c("T01", "T02", "T03", "T04", "T05", "T06",
? ? ? ?? "T07", "T08", "T09", "T10"),
? ? ? date = c("2012-10-19", "2012-10-19", "2012-10-19",
? ? ? ?? "2012-10-19", "2012-10-22", "2012-10-23",
? ? ? ?? "2012-10-23", "2012-10-23", "2012-10-23",
? ? ? ?? "2012-10-23"),
? ? ? time = c("08:00", "09:00", "10:00", "11:00", "12:00",
? ? ? ?? "13:00", "14:00", "15:00", "16:00", "17:00"
? ? ? ?? ))
(Convert the date and time to your favorite classes, it doesn't matter
here.)
A general way to say if an item is the last of its group is:
?? isLastInGroup <- function(...)? ave(logical(length(..1)), ...,
FUN=function(x)seq_along(x)==length(x))
?? is_last_of_dayA <- with(d, isLastInGroup(date))
If you know your data is sorted by date you could save a little time for
large
datasets by using
?? isLastInRun <- function(x) c(x[-1] != x[-length(x)], TRUE)
?? is_last_of_dayB <- isLastInRun(d$date)
The above d is sorted by date so you get the same results for both:
?? > cbind(d, is_last_of_dayA, is_last_of_dayB)
? ? ? transaction? ? ?? date? time is_last_of_dayA is_last_of_dayB
?? 1? ? ? ? ? T01 2012-10-19 08:00? ? ? ? ?? FALSE? ? ? ? ?? FALSE
?? 2? ? ? ? ? T02 2012-10-19 09:00? ? ? ? ?? FALSE? ? ? ? ?? FALSE
?? 3? ? ? ? ? T03 2012-10-19 10:00? ? ? ? ?? FALSE? ? ? ? ?? FALSE
?? 4? ? ? ? ? T04 2012-10-19 11:00? ? ? ? ? ? TRUE? ? ? ? ? ? TRUE
?? 5? ? ? ? ? T05 2012-10-22 12:00? ? ? ? ? ? TRUE? ? ? ? ? ? TRUE
?? 6? ? ? ? ? T06 2012-10-23 13:00? ? ? ? ?? FALSE? ? ? ? ?? FALSE
?? 7? ? ? ? ? T07 2012-10-23 14:00? ? ? ? ?? FALSE? ? ? ? ?? FALSE
?? 8? ? ? ? ? T08 2012-10-23 15:00? ? ? ? ?? FALSE? ? ? ? ?? FALSE
?? 9? ? ? ? ? T09 2012-10-23 16:00? ? ? ? ?? FALSE? ? ? ? ?? FALSE
?? 10? ? ? ?? T10 2012-10-23 17:00? ? ? ? ? ? TRUE? ? ? ? ? ? TRUE
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
Of ramoss
Sent: Friday, October 19, 2012 10:52 AM
To: r-help at r-project.org
Subject: [R] Creating a new by variable in a dataframe
Hello,
I have a dataframe w/ 3 variables of interest: transaction,date(tdate) &
time(event_tim).
How could I create a 4th variable (last_trans) that would flag the last
transaction of the day for each day?
In SAS I use:
proc sort data=all6;
by tdate event_tim;
run;
? ? ? ? ? /*Create last transaction flag per day*/
data all6;
?? set all6;
?? by tdate event_tim;
?? last_trans=last.tdate;
Thanks ahead for any suggestions.
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