On Fri, Jan 22, 2016 at 01:20:59PM -0600, Ed Siefker wrote: > Aggregate does the right thing with column names when passing it > numerical coordinates. > Given a dataframe like this: > > Nuclei Positive Nuclei Slide > 1 133 96 A1 > 2 96 70 A1 > 3 62 52 A2 > 4 60 50 A2 > > I can call 'aggregate' like this: > > > aggregate(example[1], by=example[3], sum) > Slide Nuclei > 1 A1 229 > 2 A2 122 > > But that means I have to keep track of which column is which number. > If I try it the > easy way, it doesn't keep track of column names and it forces me to > coerce the 'by' > to a list. > > > aggregate(example$Nuclei, by=list(example$Slide), sum) > Group.1 x > 1 A1 229 > 2 A2 122 > > Is there a better way to do this? Thanks > -Ed > ....
Something like: > aggregate(Nuclei ~ Slide, example, sum) Slide Nuclei 1 A1 229 2 A2 122 > perhaps? Peace, david -- David H. Wolfskill r...@catwhisker.org Those who would murder in the name of God or prophet are blasphemous cowards. See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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