Hello Ravi, I was also trying to write down such a calculation but I did not manage (I didn't use diff(x)). Thank you for the solution. Ptit Bleu.
Ravi Varadhan wrote: > > Here is a simple trapezoidal rule integrator: > > x <- time > y <- value > > area <- sum(diff(x)*(y[-1]+y[-length(y)]))/2 > > Ravi. > > > ---------------------------------------------------------------------------- > ------- > > Ravi Varadhan, Ph.D. > > Assistant Professor, The Center on Aging and Health > > Division of Geriatric Medicine and Gerontology > > Johns Hopkins University > > Ph: (410) 502-2619 > > Fax: (410) 614-9625 > > Email: [EMAIL PROTECTED] > > Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html > > > > ---------------------------------------------------------------------------- > -------- > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > On > Behalf Of Ptit_Bleu > Sent: Tuesday, September 18, 2007 11:24 AM > To: r-help@r-project.org > Subject: Re: [R] RE : Must be easy, but haven't found the function > (numerical integration) > > > Thanks to all. > > cumsum can be helpful but the solution given by David seems to match my > request. > I will test it as soon as possible (before the end of the week, I hope). > > Have a nice end of day, > Ptit Bleu. > > > > GOUACHE David wrote: >> >> try : >> >> library(Bolsatd) >> ?sintegral >> >> or: >> >> library(caTools) >> ?trapz >> >> David Gouache >> Arvalis - Institut du Végétal >> Station de La Minière >> 78280 Guyancourt >> Tel: 01.30.12.96.22 / Port: 06.86.08.94.32 >> >> >> -----Message d'origine----- >> De : Ptit_Bleu [mailto:[EMAIL PROTECTED] >> Envoyé : lundi 17 septembre 2007 12:09 >> À : [EMAIL PROTECTED] >> Objet : [R] Must be easy,but haven't found the function (numerical >> integration) >> >> >> Hi, >> >> I have a data frame of 2 columns with the following types : >> data$day char >> data$value num >> >> And I plot my data with : >> plot(strptime(donnees$day,format="%Y-%m-%d %H:%M:%S"),donnees$value, >> type="l") >> >> And I'd just like to get the numerical value of the integration of this >> graph. >> I looked at ?integrate but, as far as I understood (that is, not very >> much, >> due to my poor english), it seems that it doesn't work with values in >> data >> frame. >> >> Could you please help me to do this ? >> >> Thanks in advance, >> Have a nice week, >> Ptit Bleu. >> -- >> View this message in context: >> > http://www.nabble.com/Must-be-easy%2C-but-haven%27t-found-the-function-%28nu > merical-integration%29-tf4465684.html#a12732936 >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. >> >> > > -- > View this message in context: > http://www.nabble.com/Must-be-easy%2C-but-haven%27t-found-the-function-%28nu > merical-integration%29-tf4465684.html#a12759423 > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > > -- View this message in context: http://www.nabble.com/Must-be-easy%2C-but-haven%27t-found-the-function-%28numerical-integration%29-tf4465684.html#a12792420 Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
