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Raghuraman Ramachandran

2012-Jul-24 06:40 UTC

[R] Collapsing a vector/data-frame based on the previous values

Hello

I have a data frame like this:
dput(states)
structure(list(Date = c("24/07/2012", "25/07/2012",
"26/07/2012",
"27/07/2012", "28/07/2012", "24/07/2012",
"25/07/2012", "26/07/2012",
"27/07/2012", "28/07/2012"), State = c(1L, 1L, 1L, 1L, 1L,
-1L,
-1L, -1L, 1L, -1L)), .Names = c("Date", "State"), class =
"data.frame",
row.names = c(NA,
-10L))
> State
      Date State
1  24/07/2012     1
2  25/07/2012     1
3  26/07/2012     1
4  27/07/2012     1
5  28/07/2012     1
6  24/07/2012    -1
7  25/07/2012    -1
8  26/07/2012    -1
9  27/07/2012     1
10 28/07/2012    -1

I wish to collapse it into a smaller one based on the state value. If state
is 1 already then the second state (and the row) is to be removed till a
new state is found and so on.. States can be 1 or -1 only. So in the
previous example the new data frame should be:

  Date State  24/07/2012 1  24/07/2012 -1  27/07/2012 1  28/07/2012 -1  Can
someone help?

Thx
Raghu

	[[alternative HTML version deleted]]

Raghuraman Ramachandran

2012-Jul-24 09:21 UTC

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[R] Collapsing a vector/data-frame based on the previous values

That helps a lot mate. Thanks.

On Tue, Jul 24, 2012 at 9:50 AM, Rui Barradas <ruipbarradas@sapo.pt>
wrote:
> Hello,
>
> Step by step way:
>
>
> inx <- rle(states$State)$lengths
> inx <- cumsum(c(1, inx))
> inx <- inx[inx <= nrow(states)]
> states[inx, ]
>
> Hope this helps,
>
> Rui Barradas
>
> Em 24-07-2012 07:40, Raghuraman Ramachandran escreveu:
>
>> Hello
>>
>> I have a data frame like this:
>> dput(states)
>> structure(list(Date = c("24/07/2012", "25/07/2012",
"26/07/2012",
>> "27/07/2012", "28/07/2012", "24/07/2012",
"25/07/2012", "26/07/2012",
>> "27/07/2012", "28/07/2012"), State = c(1L, 1L, 1L,
1L, 1L, -1L,
>> -1L, -1L, 1L, -1L)), .Names = c("Date", "State"),
class = "data.frame",
>> row.names = c(NA,
>> -10L))
>>
>>  State
>>>
>>        Date State
>> 1  24/07/2012     1
>> 2  25/07/2012     1
>> 3  26/07/2012     1
>> 4  27/07/2012     1
>> 5  28/07/2012     1
>> 6  24/07/2012    -1
>> 7  25/07/2012    -1
>> 8  26/07/2012    -1
>> 9  27/07/2012     1
>> 10 28/07/2012    -1
>>
>> I wish to collapse it into a smaller one based on the state value. If
>> state
>> is 1 already then the second state (and the row) is to be removed till
a
>> new state is found and so on.. States can be 1 or -1 only. So in the
>> previous example the new data frame should be:
>>
>>    Date State  24/07/2012 1  24/07/2012 -1  27/07/2012 1  28/07/2012 -1
>>  Can
>> someone help?
>>
>> Thx
>> Raghu
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________**________________
>> R-help@r-project.org mailing list
>>
https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help>
>> PLEASE do read the posting guide http://www.R-project.org/**
>> posting-guide.html <http://www.R-project.org/posting-guide.html>
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
	[[alternative HTML version deleted]]

jim holtman

2012-Jul-24 13:25 UTC

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[R] Collapsing a vector/data-frame based on the previous values

Here is another way of doing it:
> states <- structure(list(Date = c("24/07/2012",
"25/07/2012", "26/07/2012",+ "27/07/2012", "28/07/2012", "24/07/2012",
"25/07/2012", "26/07/2012",
+ "27/07/2012", "28/07/2012"), State = c(1L, 1L, 1L, 1L, 1L,
-1L,
+ -1L, -1L, 1L, -1L)), .Names = c("Date", "State"), class =
"data.frame",
+ row.names = c(NA,
+ -10L))> # mark the state changes
> states$diff <- c(TRUE, diff(states$State) != 0)
> states[states$diff,]         Date State diff
1  24/07/2012     1 TRUE
6  24/07/2012    -1 TRUE
9  27/07/2012     1 TRUE
10 28/07/2012    -1 TRUE


On Tue, Jul 24, 2012 at 2:40 AM, Raghuraman Ramachandran
<optionsraghu at gmail.com> wrote:> Hello
>
> I have a data frame like this:
> dput(states)
> structure(list(Date = c("24/07/2012", "25/07/2012",
"26/07/2012",
> "27/07/2012", "28/07/2012", "24/07/2012",
"25/07/2012", "26/07/2012",
> "27/07/2012", "28/07/2012"), State = c(1L, 1L, 1L, 1L,
1L, -1L,
> -1L, -1L, 1L, -1L)), .Names = c("Date", "State"), class
= "data.frame",
> row.names = c(NA,
> -10L))
>
>> State
>
>       Date State
> 1  24/07/2012     1
> 2  25/07/2012     1
> 3  26/07/2012     1
> 4  27/07/2012     1
> 5  28/07/2012     1
> 6  24/07/2012    -1
> 7  25/07/2012    -1
> 8  26/07/2012    -1
> 9  27/07/2012     1
> 10 28/07/2012    -1
>
> I wish to collapse it into a smaller one based on the state value. If state
> is 1 already then the second state (and the row) is to be removed till a
> new state is found and so on.. States can be 1 or -1 only. So in the
> previous example the new data frame should be:
>
>   Date State  24/07/2012 1  24/07/2012 -1  27/07/2012 1  28/07/2012 -1  Can
> someone help?
>
> Thx
> Raghu
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

arun

2012-Jul-25 02:14 UTC

head link

[R] Collapsing a vector/data-frame based on the previous values

Hello,

Try this:

#dat1 - data
?diff2<-c(TRUE,ifelse(diff(dat1$State)>0|diff(dat1$State)<0,TRUE,FALSE))
? dat1[diff2,1:2]
?# ?????? Date State
#1? 24/07/2012???? 1
#6? 24/07/2012??? -1
#9? 27/07/2012???? 1
#10 28/07/2012??? -1


A.K.



----- Original Message -----
From: Raghuraman Ramachandran <optionsraghu at gmail.com>
To: R Project Help <r-help at r-project.org>
Cc: 
Sent: Tuesday, July 24, 2012 2:40 AM
Subject: [R] Collapsing a vector/data-frame based on the previous values

Hello

I have a data frame like this:
dput(states)
structure(list(Date = c("24/07/2012", "25/07/2012",
"26/07/2012",
"27/07/2012", "28/07/2012", "24/07/2012",
"25/07/2012", "26/07/2012",
"27/07/2012", "28/07/2012"), State = c(1L, 1L, 1L, 1L, 1L,
-1L,
-1L, -1L, 1L, -1L)), .Names = c("Date", "State"), class =
"data.frame",
row.names = c(NA,
-10L))
> State
? ? ? Date State
1? 24/07/2012? ?  1
2? 25/07/2012? ?  1
3? 26/07/2012? ?  1
4? 27/07/2012? ?  1
5? 28/07/2012? ?  1
6? 24/07/2012? ? -1
7? 25/07/2012? ? -1
8? 26/07/2012? ? -1
9? 27/07/2012? ?  1
10 28/07/2012? ? -1

I wish to collapse it into a smaller one based on the state value. If state
is 1 already then the second state (and the row) is to be removed till a
new state is found and so on.. States can be 1 or -1 only. So in the
previous example the new data frame should be:

? Date State? 24/07/2012 1? 24/07/2012 -1? 27/07/2012 1? 28/07/2012 -1? Can
someone help?

Thx
Raghu

??? [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
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.

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