(Forgot to cc. reply to K. Elo, apologies if you get it twice)
K. Elo wrote:
Dear Anna,
19.02.2010 08:17, Anna Carter wrote:
(1) If the dataset contains some variables having all the entries = 0
and while analysing I want to delete those pericular columns, how do
acheive this. i.e.
Let's suppose 'df' is your data frame, then:
subset(df, select=which(colSums(df)!=0))
should do the work :)
Beware negative entries in df! which(colSums(df!=0)) may work better,
but it is a bit "sneaky".
I'd also avoid subset in favour of df[....] or df[,....]. And why use
indexing with which() when you can use the logical index directly?
My preference goes to df[,apply(df,2,any)] (a student assistant once
almost killed me when I showed her that after she had spent days
programming the same thing using loops and whatnots...)
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalga...@biostat.ku.dk) FAX: (+45) 35327907
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