[R] Strange column shifting with read.table

[Rolf Turner]

On 3/08/2009, at 3:43 PM, David Winsemius wrote:

>
> On Aug 2, 2009, at 10:46 PM, Rolf Turner wrote:
>
>>
>> On 3/08/2009, at 1:48 PM, David Winsemius wrote:
>>
>>>
>>> On Aug 2, 2009, at 7:29 PM, Rolf Turner wrote:
>>>
>>>>
>>>> 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.\\
>>>
>>> Then how about? ....
>>>
>>> junk2 <- replace(junk, is.na(junk), 0)
>>
>> That certainly works --- and is a potentially useful piece of syntax
>> of which I was
>> previously unaware (thank you) --- but the OP's syntax also worked
>> (and gives identical results
>> to yours).  I.e. the OP's problem was *not* induced by the way he
>> went about replacing
>> NA's by zeroes, irrespective of the fact that that's a silly thing
>> to do.
>
> Go back to the original posting. The OP was complaining about the fact
> that rawdata[is.na(rawdata)] <- 0 threw an error before he ran that R
> object through scale. He did not realize that rawdata was a dataframe
> in the first instance and a matrix in the second. The syntax of the
> "[" operator  would not support the construction that he and you were
> using when it was applied to a dataframe. The code I offered does not
> seem to suffer from that deficiency.

OK.  I get it now.

	cheers,

		Rolf Turner

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