[R] / Operator not meaningful for factors

[Gabor Grothendieck]

But factors are numeric:

mode(factor(1:3)) # numeric

so the numerator or denominator are likely a factor.
Try using str and class rather than mode to investigate
this.


On 1/15/06, Vivek Satsangi <vivek.satsangi at gmail.com> wrote:
> Folks,
> I have a very basic question. The solution eludes me perhaps because
> of my own lack of creativity. I am not attaching a fully reproducible
> session because the issue may well be becuase of the way the data file
> is, and the data file is large (and I don't know whether I can legally
> distribute it). If people can suggest things that might be wrong in my
> data or the way that I am reading it, I would be most grateful.
>
> I get the following error message in the session quoted at the end of
> this email:
> / not meaningful for factors in: Ops.factor(BookValuePS, Price)
>
> As you can see in that some session, I check that the two vectors
> being divided are numeric. I also check that the divisor is not 0 at
> any index. I also believe that this is not because of the NA's in the
> data. My question is, what are other "problems" that can cause the /
> operator to not be meaningful?
>
> I did try some simple examples to try to get the same error. However,
> I am not sure how to put the same NA's that one  gets from
> read.table() into a vector:
> > a <- c(1, 2, 3, NA);
> > a
> [1]  1  2  3 NA
> > b <- c( 1, 2, 3, 4);
> > c <- b / a;
> > b
> [1] 1 2 3 4
> > a <- c(1, 2, 3, );
> > c <- b/a;
> Warning message:
> longer object length
>        is not a multiple of shorter object length in: b/a
>
>
> ******** Quoted Session below ********
>  > explainPriceSimplified <- read.table("combinedClean.csv",
> +                            sep = ",", header=TRUE);
> > attach(explainPriceSimplified);
> > summary(explainPriceSimplified);
>     Symbol           Date              Price            EPS
>   BookValuePS
>  XL     :   98   Min.   :19870630   22     :   61   Min.   :-1.401e+05
>  Min.   :-6.901e+05
>  ZION   :   97   1st Qu.:19910930   26.5   :   61   1st Qu.: 4.650e-01
>  1st Qu.: 3.892e+00
>  YRCW   :   72   Median :19960331   27.5   :   58   Median : 1.060e+00
>  Median : 7.882e+00
>  AA     :   71   Mean   :19957688   30     :   58   Mean   :-1.534e+01
>  Mean   : 1.515e+02
>  ABS    :   71   3rd Qu.:20001231   25     :   56   3rd Qu.: 1.890e+00
>  3rd Qu.: 1.444e+01
>  ABT    :   71   Max.   :20041231   (Other):29561   Max.   : 5.309e+03
>  Max.   : 3.366e+06
>  (Other):29624                      NA's   :  249   NA's   : 2.460e+02
>  NA's   : 4.760e+02
>  FiscalQuarterRep    F12MRet
>  2004/2F:  482    Min.   :-100.00
>  2003/4F:  471    1st Qu.:  -8.82
>  2004/1F:  470    Median :  10.57
>  2004/3F:  470    Mean   :  13.36
>  2003/3F:  464    3rd Qu.:  31.12
>  2003/2F:  463    Max.   :4700.00
>  (Other):27284    NA's   : 463.00
> > mode(Price)
> [1] "numeric"
> > mode(EPS)
> [1] "numeric"
> > mode(BookValuePS)
> [1] "numeric"
> > BP <- BookValuePS / Price ;
> Warning message:
> / not meaningful for factors in: Ops.factor(BookValuePS, Price)
> > which(Price==0)
> numeric(0)
> >
>
>
> --
> -- Vivek Satsangi
> Student, Rochester, NY USA
>
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