Sorry... That last expression was backward...
Wb30$ValidWB <- with( Wb30, 0 == cumsum( Water_Balance < 0 | 100 <
Water_Balance ) )
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Jeff Newmiller The ..... ..... Go Live...
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Sent from my phone. Please excuse my brevity.
On October 23, 2014 7:23:15 AM PDT, Jeff Newmiller <jdnew...@dcn.davis.ca.us>
wrote:
>Counting chickens after they have left the coop is not going to work.
>If your inputs push w outside the limits of physics then your input
>data are invalid. Arbitrarily forcing w to fit in that case partially
>ignores the inputs anyway... and since there are many ways for the data
>to be invalid you should be trying to understand how your data are
>invalid so you can figure out if you can extract any meaning from it.
>Drift? Random (lots of ways... which)? Offset? Marking the bad records
>in a new status column is a start... blindly proceeding to pretend as
>though there were no problem in the data is deceptive.
>
>Once you get the input data cleaned up so you don't need to butcher the
>output, the R way to do this is
>
>Wb30$Water_Balance <- with( Wb30, cumsum( Rainfall - Evaporation ) )
>Wb30$ValidWB <- with( Wb30, 0 == cumsum( 0 <= Water_Balance &
>Water_Balance <= 100 ) )
>
>---------------------------------------------------------------------------
>Jeff Newmiller The ..... ..... Go
>Live...
>DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live
>Go...
> Live: OO#.. Dead: OO#.. Playing
>Research Engineer (Solar/Batteries O.O#. #.O#. with
>/Software/Embedded Controllers) .OO#. .OO#.
>rocks...1k
>---------------------------------------------------------------------------
>
>Sent from my phone. Please excuse my brevity.
>
>On October 23, 2014 6:35:27 AM PDT, Frederic Ntirenganya
><ntfr...@gmail.com> wrote:
>>Dear Duncan,
>>
>>Those condition should be there and also look at Rainfall and
>>evaporation
>>columns.
>>If i change it to be like the following loop, it can't do it.
>>
>>The problem is how to include those conditions and also respect the
>>formula?
>>
>>wb=c()
>>for (w in 1:length(Wb30$Water_Balance)){
>> if(w<0){
>> w=0
>> }
>>
>> wb=Wb30$Water_Balance[w-1] + Wb30$Rainfall[w]-Wb30$Evaporation[w]
>>}
>>wb
>>
>>Regards,
>>Frederic.
>>
>>Frederic Ntirenganya
>>Maseno University,
>>African Maths Initiative,
>>Kenya.
>>Mobile:(+254)718492836
>>Email: fr...@aims.ac.za
>>https://sites.google.com/a/aims.ac.za/fredo/
>>
>>On Thu, Oct 23, 2014 at 3:44 PM, Duncan Murdoch
>><murdoch.dun...@gmail.com>
>>wrote:
>>
>>> On 23/10/2014, 8:33 AM, Frederic Ntirenganya wrote:
>>> > Dear All,
>>> >
>>> > I want to calculate water balance using the following formula:
>>> > Water balance today = Water balance yesterday + Rainfall −
>>Evaporation
>>> >
>>> > This is a sample of data I am using:
>>> >
>>> > head(Wb30)
>>> > May Rainfall Evaporation Water_Balance
>>> > 1 7 0 5 0
>>> > 2 8 10 5 NA
>>> > 3 9 0 5 NA
>>> > 4 10 0 5 NA
>>> > 5 11 2 5 NA
>>> > 6 12 23 5 NA
>>> >
>>> > The following is the loop am trying to use but it is not working
>>well.
>>> >
>>> > #Water balance today = Water balance yesterday + Rainfall −
>>Evaporation
>>> > #If Water balance today < 0 then Water balance today = 0
>>> > #If Water balance today > 100 then Water balance today = 100
>>> > wb=c()
>>> > for (w in 1:length(Wb30$Water_Balance)){
>>> > if(w<0 & w>100){w<-0 & w<-100}
>>>
>>> The line above doesn't make sense. It is impossible for w to be
>both
>>> less than 0 and greater than 100, so the condition will never be
>>true.
>>> And if it is true, "w<-0 & w<-100" is not a sensible thing to do.
>>>
>>> > #print (w);
>>> > for (i in 1:length(Wb30$Rainfall)){
>>> > for (j in 1:length(Wb30$Evaporation)){
>>> > }
>>> > }
>>>
>>> Those loops do nothing.
>>>
>>> > wb<-Wb30$Water_Balance[w] +
>>Wb30$Rainfall[i+1]-Wb30$Evaporation[j+1]
>>>
>>> Those should be using w-1 in place of w, and w in place of i+1 and
>>j+1.
>>>
>>> Duncan Murdoch
>>>
>>> > }
>>> > wb
>>> >
>>> > Any suggest of what I am missing for it to work correctly is
>>welcome.
>>> >
>>> >
>>> > Regards,
>>> >
>>> > Frederic Ntirenganya
>>> > Maseno University,
>>> > African Maths Initiative,
>>> > Kenya.
>>> > Mobile:(+254)718492836
>>> > Email: fr...@aims.ac.za
>>> > https://sites.google.com/a/aims.ac.za/fredo/
>>> >
>>> > [[alternative HTML version deleted]]
>>> >
>>> > ______________________________________________
>>> > R-help@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.
>>> >
>>>
>>>
>>
>> [[alternative HTML version deleted]]
>>
>>______________________________________________
>>R-help@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@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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