Re: [R] Help/ Mathematics

[Ahmed Attia]

Hi Jim,

Thank you very much, this was so helpful.

GPP_Ahmed13$Date <- as.Date(GPP_Ahmed13$Date, '%Y/%m/%d')
Litterfall_Ahmed97$Date <- as.Date(Litterfall_Ahmed97$Date, '%Y/%m/%d')
leafbiom97$Date <- as.Date( leafbiom97$Date, '%Y/%m/%d')

(leafbiom97$LeafBiog[leafbiom97$Date == "2012-02-12"] -
  leafbiom97$LeafBiog[leafbiom97$Date == "2010-03-15"]+
  Litterfall_Ahmed97$littperiod[Litterfall_Ahmed97$Date =="2011-04-08"])/
  (sum(GPP_Ahmed13$GPP[GPP_Ahmed13$Date >= "2010-03-12" &
  GPP_Ahmed13$Date <= "2012-04-12"])/2)


Best regards

Ahmed
Ahmed Attia, Ph.D.
Agronomist & Soil Scientist






On Thu, Jun 22, 2017 at 12:24 AM, Jim Lemon  wrote:
> Hi Ahmed,
> Your problem appears trivial as you have already specified the form of
> the calculation.
>
> Learn how to "extract" specified elements from a data structure:
>
> # first value
> sum(dataset1$NPP[dataset1$date >= date1 &
>  dataset1$date <= date2])
> # second value
> dataset2$biomass[dataset2$date == date2] -
>  dataset2$biomass[dataset2$date == date1]
> # third value
> dataset3$littfall[dataset3$date == date2]
>
> Note that you may have to convert character strings to dates to do the
> above - see a function like "as.Date". Obviously I do not know the
> actual names of your datasets and I am assuming that the variable
> names you have given are the actual ones.
>
> Jim
>
>
> On Thu, Jun 22, 2017 at 4:19 AM, Ahmed Attia  wrote:
>> Hi R users,
>>
>> I need your help to write a code in r that does the following
>> calculation from three different datasets;
>>
>> ac = 1/sum (NPP from date 1 to date 2, dataset=1) * (biomass at date 2
>> -biomass at date 1, dataset = 2) + (littfall at date 2, dataset=3).
>>
>> all the dates are in yr-month-day format. Which library or function
>> Should I use to tell R do these calculations of these variables at
>> different dates.
>>
>> I appreciate your help.
>>
>> Ahmed Attia, Ph.D.
>> Agronomist & Soil Scientist
>>
>> __
>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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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and provide commented, minimal, self-contained, reproducible code.

Re: [R] Help/ Mathematics

[David Winsemius]

> On Jun 21, 2017, at 11:19 AM, Ahmed Attia  wrote:
> 
> Hi R users,
> 
> I need your help to write a code in r that does the following
> calculation from three different datasets;
> 
> ac = 1/sum (NPP from date 1 to date 2, dataset=1) * (biomass at date 2
> -biomass at date 1, dataset = 2) + (littfall at date 2, dataset=3).

To do this in R you could learn to use the "sqldf"-package since you seem 
familiar with that syntax. I'm not and so it's rank speculation on my part that 
such an expression would be meaningful in one or another flavor of SQL.

Or you could use either `match` or `merge`, assuming the dates of the various 
datasets are congruent.


> 
> all the dates are in yr-month-day format.

The "-MM-DD" format is the standard format in R. You might not even need to 
convert to the Date-class.


> Which library or function
> Should I use to tell R do these calculations of these variables at
> different dates.
> 
> I appreciate your help.
> 
> Ahmed Attia, Ph.D.
> Agronomist & Soil Scientist
> 
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.

David Winsemius
Alameda, CA, USA

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.

Re: [R] Help/ Mathematics

[Jim Lemon]

Hi Ahmed,
Your problem appears trivial as you have already specified the form of
the calculation.

Learn how to "extract" specified elements from a data structure:

# first value
sum(dataset1$NPP[dataset1$date >= date1 &
 dataset1$date <= date2])
# second value
dataset2$biomass[dataset2$date == date2] -
 dataset2$biomass[dataset2$date == date1]
# third value
dataset3$littfall[dataset3$date == date2]

Note that you may have to convert character strings to dates to do the
above - see a function like "as.Date". Obviously I do not know the
actual names of your datasets and I am assuming that the variable
names you have given are the actual ones.

Jim


On Thu, Jun 22, 2017 at 4:19 AM, Ahmed Attia  wrote:
> Hi R users,
>
> I need your help to write a code in r that does the following
> calculation from three different datasets;
>
> ac = 1/sum (NPP from date 1 to date 2, dataset=1) * (biomass at date 2
> -biomass at date 1, dataset = 2) + (littfall at date 2, dataset=3).
>
> all the dates are in yr-month-day format. Which library or function
> Should I use to tell R do these calculations of these variables at
> different dates.
>
> I appreciate your help.
>
> Ahmed Attia, Ph.D.
> Agronomist & Soil Scientist
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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 -- To UNSUBSCRIBE and more, see
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.

Re: [R] Help/ Mathematics

[Bert Gunter]

We expect posters to have made an effort to learn R and show us code
that they have tried. We do not provide free software development. The
"Introduction to R" tutorial that ships with the software is one place
to start, but there are many good web tutorials also available. Just
search.

Cheers,
Bert


Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Wed, Jun 21, 2017 at 11:19 AM, Ahmed Attia  wrote:
> Hi R users,
>
> I need your help to write a code in r that does the following
> calculation from three different datasets;
>
> ac = 1/sum (NPP from date 1 to date 2, dataset=1) * (biomass at date 2
> -biomass at date 1, dataset = 2) + (littfall at date 2, dataset=3).
>
> all the dates are in yr-month-day format. Which library or function
> Should I use to tell R do these calculations of these variables at
> different dates.
>
> I appreciate your help.
>
> Ahmed Attia, Ph.D.
> Agronomist & Soil Scientist
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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 -- To UNSUBSCRIBE and more, see
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/ Mathematics

[Ahmed Attia]

Hi R users,

I need your help to write a code in r that does the following
calculation from three different datasets;

ac = 1/sum (NPP from date 1 to date 2, dataset=1) * (biomass at date 2
-biomass at date 1, dataset = 2) + (littfall at date 2, dataset=3).

all the dates are in yr-month-day format. Which library or function
Should I use to tell R do these calculations of these variables at
different dates.

I appreciate your help.

Ahmed Attia, Ph.D.
Agronomist & Soil Scientist

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.