[R] Incremental

[Rui Barradas]

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
>>>
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>>>
>>