[R] Removing "NA" from matrix

[David Winsemius]

On Jun 14, 2013, at 7:03 AM, Katherine Gobin wrote:

> Dear R forum,
> 
> I have a data frame 
> 
> 
> dat = data.frame(
> ABC = c(25.28000732,48.33857234,19.8013245,10.68361461),
> DEF = c(14.02722251,10.57985168,11.81890316,21.40171514),
> GHI = c(1,1,1,1),
> JKL = c(45.96423231,44.52986236,16.56514176,32.14545122),
> MNO = c(45.38438063,15.54338206,18.78444777,24.29486984))
> 
>> dat
>        ABC      DEF GHI      JKL      MNO
> 1 25.28001 14.02722   1 45.96423 45.38438
> 2 48.33857 10.57985   1 44.52986 15.54338
> 3 19.80132 11.81890   1 16.56514 18.78445
> 4 10.68361 21.40172   1 32.14545 24.29487
> 
> 
> When I try to find the correlation I get (which is obvious as my one column shows no variation)

Perhaps:

dat_cor = cor(dat[ , sapply(dat, function(col) sd(col) != 0 ) ] )

> Warning message:
> In cor(dat) : the standard deviation is zero
>> dat_cor
>            ABC         DEF GHI         JKL        MNO
> ABC  1.0000000 -0.75600764  NA  0.55245223 -0.2735585
> DEF -0.7560076  1.00000000  NA -0.06479082  0.2020781
> GHI         NA          NA   1          NA         NA
> JKL  0.5524522 -0.06479082  NA  1.00000000  0.4564568
> MNO -0.2735585  0.20207810  NA  0.45645683  1.0000000
> 
> 
> In reality I am dealing with about 300 variables and don't know which variables don't vary.
> 
> My query is how do I remove the columns and rows with NA's.
> 
> So for example, I need the correlation matrix for ABC, DEF, JKL and MNO only.
> 
> Kindly guide.
> 
> Thanking in advance.
> 
> Regards
> 
> Katherine
> 
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> 
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David Winsemius
Alameda, CA, USA