[R] issues with identical()

[Duncan Murdoch]

Jean Eid wrote:
> Hi all, hope you having a nice day,
> 
> I ahve this weird results with identical (probably I am not understanding
> correctly what it does ...)
> 
> I have these two data frames and I issue :
> 
>>identical(temp, temp1)
> 
> [1] FALSE
> 
> 
> However, these data frames are Nx2 and when I issue:
> 
>>identical(temp[,2], temp1[,2])
> 
> [1] TRUE
> 
>>identical(temp[,1], temp1[,1])
> 
> [1] TRUE
> 
> and the results from str
> 
> 
> 
>>str(temp)
> 
> `data.frame':	7072 obs. of  2 variables:
>  $ pub_id  : int  10000 1000 10001 10002 10003 10004 10005 10006 10007
>  $ faminc90: int  -2 5998 19900 43000 35000 40000 56538 61000 36000 39105
> 
>>str(temp1)
> 
> `data.frame':	7072 obs. of  2 variables:
>  $ pub_id: int  10000 1000 10001 10002 10003 10004 10005 10006 10007 10008
>  $ faminc: int  -2 5998 19900 43000 35000 40000 56538 61000 36000 39105
> 
> The question is why are the objects different. How else can I tell what is
> the difference

There could be a difference in the attributes (e.g. rownames of the 
dataframe, or names of one of the columns).

One thing that might turn up the difference is to use dump() to write 
out the objects to a file, and use some text-based compare on those files.

Duncan Murdoch