[R] Strange column shifting with read.table

[Rolf Turner]

On 3/08/2009, at 11:14 AM, David Winsemius wrote:

>
> On Aug 2, 2009, at 7:02 PM, Noah Silverman wrote:
>
>> Hi,
>>
>> It seems as if the problem was caused by an odd quirk of the "scale"
>> function.
>>
>> Some of my data have NA entries.
>>
>> So, I substitute 0 for any NA with:
>> rawdata[is.na(rawdata)] <- 0
>
> Perhaps this would have done what you intended:
>
> rawdata[is.na(rawdata), ] <- 0

	I don't think this works at all.  E.g.:

	set.seed(42)
	junk <- matrix(rnorm(60),12,5)
	junk[sample(1:60,14)] <- NA
	junk[is.na(junk),] <- 0 # Throws an error.
	junk[is.na(junk)] <- 0  # Gives the desired result.
>
> # But this is added _only_ as a matter of coding behavior. See below.

	<snip>

> The notion of adding zeroes for NA seems "so wrong". And the idea that
> you might get the same results of doing so before scale() as after
> scale() seems additionally bizarre.
>
>
>>
>> VERY strange behavior.
>>
>
> Your behavior might be seen as VERY strange by some.

	I concur, heartily.  Conflating NA with 0 is a first year student error
	that is almost never anything other than just plain silly.

		cheers,

			Rolf Turner

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