[R] Incremental

[Val]

Thank you Rui,

It Worked!

How about if the first variable is date format? Like the following
dat<-read.table(text=" y1, flag
24-01-2016,S
24-02-2016,R
24-03-2016,X
24-04-2016,H
24-01-2016,S
24-11-2016,R
24-10-2016,R
24-02-2016,X
24-01-2016,H
24-11-2016,S
24-02-2016,R
24-10-2016,X
24-03-2016,H
24-04-2016,S
",sep=",",header=TRUE)
dat
dat$x1 <- cumsum(dat$flag == "S")
dat$z2 <- unlist(tapply(dat$y1, dat$x1, function(y) y - y[1]))

error message
In Ops.factor(y, y[1]) : ‘-’ not meaningful for factors



On Thu, Oct 13, 2016 at 5:30 AM, Rui Barradas <ruipbarradas at sapo.pt> wrote:
> Hello,
>
> You must run the code to create x1 first, part 1), then part 2).
> I've tested with your data and all went well, the result is the following.
>
>> dput(dat)
> structure(list(y1 = c(39958L, 40058L, 40105L, 40294L, 40332L,
> 40471L, 40493L, 40533L, 40718L, 40771L, 40829L, 40892L, 41056L,
> 41110L, 41160L, 41222L, 41250L, 41289L, 41324L, 41355L, 41415L,
> 41562L, 41562L, 41586L), flag = structure(c(3L, 2L, 4L, 1L, 3L,
> 2L, 2L, 4L, 1L, 3L, 2L, 4L, 1L, 3L, 2L, 2L, 2L, 2L, 4L, 2L, 4L,
> 4L, 1L, 3L), .Label = c("H", "R", "S", "X"), class = "factor"),
>     x1 = c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L,
>     4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 5L), z2 = c(0L, 100L,
>     147L, 336L, 0L, 139L, 161L, 201L, 386L, 0L, 58L, 121L, 285L,
>     0L, 50L, 112L, 140L, 179L, 214L, 245L, 305L, 452L, 452L,
>     0L)), .Names = c("y1", "flag", "x1", "z2"), row.names = c(NA,
> -24L), class = "data.frame")
>
>
> Rui Barradas
>
>
> Em 12-10-2016 21:53, Val escreveu:
>>
>> Rui,
>> Thank You!
>>
>> the second one gave me NULL.
>> dat$z2 <- unlist(tapply(dat$y1, dat$x1, function(y) y - y[1]))
>>
>> dat$z2
>> NULL
>>
>>
>>
>> On Wed, Oct 12, 2016 at 3:34 PM, Rui Barradas <ruipbarradas at sapo.pt>
>> wrote:
>>>
>>> Hello,
>>>
>>> Seems simple:
>>>
>>>
>>> # 1)
>>> dat$x1 <- cumsum(dat$flag == "S")
>>>
>>> # 2)
>>> dat$z2 <- unlist(tapply(dat$y1, dat$x1, function(y) y - y[1]))
>>>
>>> Hope this helps,
>>>
>>> Rui Barradas
>>>
>>>
>>> Em 12-10-2016 21:15, Val escreveu:
>>>>
>>>>
>>>> Hi all,
>>>>
>>>> I have a data set like
>>>> dat<-read.table(text=" y1, flag
>>>> 39958,S
>>>> 40058,R
>>>> 40105,X
>>>> 40294,H
>>>> 40332,S
>>>> 40471,R
>>>> 40493,R
>>>> 40533,X
>>>> 40718,H
>>>> 40771,S
>>>> 40829,R
>>>> 40892,X
>>>> 41056,H
>>>> 41110,S
>>>> 41160,R
>>>> 41222,R
>>>> 41250,R
>>>> 41289,R
>>>> 41324,X
>>>> 41355,R
>>>> 41415,X
>>>> 41562,X
>>>> 41562,H
>>>> 41586,S
>>>> ",sep=",",header=TRUE)
>>>>
>>>> First sort the data by y1.
>>>> Then
>>>> I want to create two columns .
>>>> 1. the first new column is  (x1):  if flag is "S"  then  x1=1  and
>>>> assign the following/subsequent rows 1 as well.   When we reach to
>>>> the next "S"  then  x1=2 and the subsequent rows will be assigned to
>>>> 2.
>>>>
>>>> 2. the second variable (z2). Within each x1 find the difference
>>>> between the first y1 and subsequent y1 values
>>>>
>>>> Example  for the first few rows
>>>>     y1,   flag, x1, z2
>>>> 39958, S, 1,    0          z2 is calculated as     z2=(39958, 39958)
>>>> 40058, R, 1, 100         z2 is calculated as     z2=(40058, 39958)
>>>> 40105, X, 1, 147         z2 is calculated as     z2=(40105, 39958)
>>>> 40294, H, 1, 336         z2 is calculated as     z2=(40294, 39958)
>>>> 40332, S, 2,  0            z2 is calculated as     z2=(40332, 40332)
>>>> etc
>>>>
>>>> Here is the complete output for the sample  data
>>>> 39958,S,1,0
>>>> 40058,R,1,100
>>>> 40105,X,1,147
>>>> 40294,H,1,336
>>>> 40332,S,2,0
>>>> 40471,R,2,139
>>>> 40493,R,2,161
>>>> 40533,X,2,201
>>>> 40718,H,2,386
>>>> 40771,S,3,0
>>>> 40829,R,3,58
>>>> 40892,X,3,121
>>>> 41056,H,3,285
>>>> 41110,S,4,0
>>>> 41160,R,4,50
>>>> 41222,R,4,112
>>>> 41250,R,4,140
>>>> 41289,R,4,179
>>>> 41324,X,4,214
>>>> 41355,R,4,245
>>>> 41415,X,4,305
>>>> 41562,X,4,452
>>>> 41562,H,4,452
>>>> 41586,S,5,0
>>>>
>>>> Val
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>