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 IngenierÃa 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.
