Hi ms. also try this:
sd(Ht_cm[type=='SD' && from_treeline=='above']) cause i think you can't use [][] two apply 2 conditions to a data frame, in that cases you should use an AND (&&) conector like above 2009/10/27 marcos carvajalino <maancafe...@gmail.com>: > Dear ms. > > The most possible reason for this: > >>Dear all >>I am trying to learn R >>I was trying to calculate standard deviation >>here are the commands and outputs in R >>> sd(Ht_cm[type=='SD'])[1] 3.283605> sd(Ht_cm[from_treeline=='above'])[1] >>> 16.83289> >sd(Ht_cm[type=='SD'][from_treeline=='above'])[1] NA> > >>the problem is that, i could not understand why the third command could not >>give any >result. > >>please help me out > >>thanking you > >>Regard >>MS >>Nepal > > is that you're trying to calculate sd over a vector where a NA (Not > available) value is contained, that is, you have an empty cell, a > different type of data or no data satisfies your condition, try: > >>sd(Ht_cm[type=='SD'][from_treeline=='above'],na.rm=T) > > That should do it... > > -- > Marcos Antonio Carvajalino Fernández > Estudiante de Ingeniería Ambiental y Sanitaria > Universidad del Magdalena, Colombia > -- Marcos Antonio Carvajalino Fernández Estudiante de Ingeniería Ambiental y Sanitaria Universidad del Magdalena, Colombia ______________________________________________ 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.
