[R] Sum of two consecutive number in dataset.

Wed Oct 15 17:34:23 CEST 2014

twodays <- c(filter(x,c(1,1),sides=1))

might be more efficient with memory than the embed approach, which might be important if more than two days were of interest.
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Sent from my phone. Please excuse my brevity.

On October 15, 2014 2:59:40 AM PDT, PIKAL Petr <petr.pikal at precheza.cz> wrote:
>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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