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Frederic Ntirenganya

2014-Oct-15 07:01 UTC

[R] Sum of two consecutive number in dataset.

Dear All,

i am solving the following problem in my work.

The first day from April 01 that gets more than 20 mm on a single day, or
totalled
over 2 consecutive days. i.e April 01 = 92th day of the year.

The column of interest is "Rain".> head(Samaru56)  Year Day Rain
1 1928   1    0
2 1928   2    0
3 1928   3    0
4 1928   4    0
5 1928   5    0
6 1928   6    0

I used the loop below but it is not printing anything.

sow_day=c()
for (i in 1928:1983){
  for (j in 92:366){
    k=j-1
    s_rain=Samaru56$Rain[k] + Samaru56$Rain[j]
    if (s_rain>=20)
      sow_day=j
      break
  }
  Samaru56$year=Samaru56$Year[sow_day]
  Samaru56$Day=Samaru56$Day[sow_day]
  Samaru56$Rain=Samaru56$Rain[sow_day]
}
sow_day

Any idea is welcome on how I can solve this problem. Thanks

-- 
Frederic Ntirenganya
Maseno University,
Kenya.
Mobile:(+254)718492836
Email: fredo at aims.ac.za
https://sites.google.com/a/aims.ac.za/fredo/

	[[alternative HTML version deleted]]

PIKAL Petr

2014-Oct-15 09:59 UTC

head link

[R] Sum of two consecutive number in dataset.

Hi

twodays <- rowSums(embed(Samaru56$Rain,2))

gives you sum of rain in 2 cosecutive days

sel <- which(twodays>20)

gives you vector of row numbers in which above condition results in TRUE value

Samaru56[sel,]

selects these rows

Regards
Petr
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Frederic Ntirenganya
> Sent: Wednesday, October 15, 2014 9:01 AM
> To: r-help at r-project.org
> Subject: [R] Sum of two consecutive number in dataset.
>
> Dear All,
>
> i am solving the following problem in my work.
>
> The first day from April 01 that gets more than 20 mm on a single day,
> or totalled over 2 consecutive days. i.e April 01 = 92th day of the
> year.
>
> The column of interest is "Rain".
> > head(Samaru56)
>   Year Day Rain
> 1 1928   1    0
> 2 1928   2    0
> 3 1928   3    0
> 4 1928   4    0
> 5 1928   5    0
> 6 1928   6    0
>
> I used the loop below but it is not printing anything.
>
> sow_day=c()
> for (i in 1928:1983){
>   for (j in 92:366){
>     k=j-1
>     s_rain=Samaru56$Rain[k] + Samaru56$Rain[j]
>     if (s_rain>=20)
>       sow_day=j
>       break
>   }
>   Samaru56$year=Samaru56$Year[sow_day]
>   Samaru56$Day=Samaru56$Day[sow_day]
>   Samaru56$Rain=Samaru56$Rain[sow_day]
> }
> sow_day
>
> Any idea is welcome on how I can solve this problem. Thanks
>
> --
> Frederic Ntirenganya
> Maseno University,
> Kenya.
> Mobile:(+254)718492836
> Email: fredo at aims.ac.za
> https://sites.google.com/a/aims.ac.za/fredo/
>
>       [[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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Tom Wright

2014-Oct-15 14:15 UTC

head link

[R] Sum of two consecutive number in dataset.

A couple of observations:
1) I'm not sure what the variable i is doing, looks like you are trying
to loop through years but perhaps you left that bit of code out for
clarity.
2) On the first loop of i you are assigning the values of
Samaru56[sow_day,] to all values in Samaru56. For future loops all
values on Samaru56 will be the same.

My approach to this problem would be:
rowCount<-nrow(Samaru56)
Samaru56$two_day<-vector(length=rowCount)

#first day doesnt have a two day value
Samaru56$two_day[2:rowCount]<-
	Samaru56$Rain[1:rowCount-1] + Samaru56$Rain[2:rowCount]

sow_day <- min(c(
		which(Samaru56$Rain > 20 & Samaru$Day>91),
		which(Samaru56$two_day > 20 & Samaru$Day>91)))


#first day doesnt have a two day value

On Wed, 2014-10-15 at 10:01 +0300, Frederic Ntirenganya
wrote:> Dear All,
> 
> i am solving the following problem in my work.
> 
> The first day from April 01 that gets more than 20 mm on a single day, or
> totalled
> over 2 consecutive days. i.e April 01 = 92th day of the year.
> 
> The column of interest is "Rain".
> > head(Samaru56)
>   Year Day Rain
> 1 1928   1    0
> 2 1928   2    0
> 3 1928   3    0
> 4 1928   4    0
> 5 1928   5    0
> 6 1928   6    0
> 
> I used the loop below but it is not printing anything.
> 
> sow_day=c()
> for (i in 1928:1983){
>   for (j in 92:366){
>     k=j-1
>     s_rain=Samaru56$Rain[k] + Samaru56$Rain[j]
>     if (s_rain>=20)
>       sow_day=j
>       break
>   }
>   Samaru56$year=Samaru56$Year[sow_day]
>   Samaru56$Day=Samaru56$Day[sow_day]
>   Samaru56$Rain=Samaru56$Rain[sow_day]
> }
> sow_day
> 
> Any idea is welcome on how I can solve this problem. Thanks
>

William Dunlap

2014-Oct-15 15:11 UTC

head link

[R] Sum of two consecutive number in dataset.

Break down your problem into parts:
# compute two-day totals.  I use filter here, but there are many ways
twoDayTotal <- function (x, init = 0)
{
    # init lets you supply rainfall from day previous to first in x
    filter(c(init, x), c(1, 1))[-length(x)]
}
# compute the first time a logical vector contains a TRUE
firstTime <-function (x, time. = as.vector(time(x)))
{
    stopifnot(is.logical(x))
    time.[!is.na(x) & x][1]
}
# combine them
f <- function(x, ...) firstTime(x>22 | twoDayTotal(x)>22, ...)
# test it
f(c(5, 20, 3, 4, 25))
# [1] 2
f(c(0, 25, 3, 4, 25), time=92:96)
# [1] 93
f(ts(c(0, 25, 3, 4, 25), start=92))
# [1] 93


Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Wed, Oct 15, 2014 at 12:01 AM, Frederic Ntirenganya
<ntfredo at gmail.com> wrote:> Dear All,
>
> i am solving the following problem in my work.
>
> The first day from April 01 that gets more than 20 mm on a single day, or
> totalled
> over 2 consecutive days. i.e April 01 = 92th day of the year.
>
> The column of interest is "Rain".
>> head(Samaru56)
>   Year Day Rain
> 1 1928   1    0
> 2 1928   2    0
> 3 1928   3    0
> 4 1928   4    0
> 5 1928   5    0
> 6 1928   6    0
>
> I used the loop below but it is not printing anything.
>
> sow_day=c()
> for (i in 1928:1983){
>   for (j in 92:366){
>     k=j-1
>     s_rain=Samaru56$Rain[k] + Samaru56$Rain[j]
>     if (s_rain>=20)
>       sow_day=j
>       break
>   }
>   Samaru56$year=Samaru56$Year[sow_day]
>   Samaru56$Day=Samaru56$Day[sow_day]
>   Samaru56$Rain=Samaru56$Rain[sow_day]
> }
> sow_day
>
> Any idea is welcome on how I can solve this problem. Thanks
>
> --
> Frederic Ntirenganya
> Maseno University,
> Kenya.
> Mobile:(+254)718492836
> Email: fredo at aims.ac.za
> https://sites.google.com/a/aims.ac.za/fredo/
>
>         [[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.

R help - Oct 2014 - Sum of two consecutive number in dataset.

[R] Sum of two consecutive number in dataset.

[R] Sum of two consecutive number in dataset.

[R] Sum of two consecutive number in dataset.

[R] Sum of two consecutive number in dataset.