[R] how to skip NA columns ?

[Peter Dalgaard BSA]

Prof Brian D Ripley <ripley at stats.ox.ac.uk> writes:

> Columns of what?  A data frame or a matrix?
> 
> For a data frame DF
> 
> hasna <- sapply(DF, function(x) any(is.na(x)))
> DF <- DF[!hasna]
> 
> and `hasna' tells which you removed.  Use apply and matrix indexing for a
> matrix.

Actually, that works in either case, since is.na on a dataframe
is a matrix:

> data(airquality)
> apply(is.na(airquality),2,any)
  Ozone Solar.R    Wind    Temp   Month     Day 
   TRUE    TRUE   FALSE   FALSE   FALSE   FALSE 
> hasna <- .Last.value
> airquality[1:10,!hasna]
   Wind Temp Month Day
1   7.4   67     5   1
2   8.0   72     5   2
3  12.6   74     5   3
4  11.5   62     5   4
5  14.3   56     5   5
6  14.9   66     5   6
7   8.6   65     5   7
8  13.8   59     5   8
9  20.1   61     5   9
10  8.6   69     5  10

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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