Hello,
I'm trying to fit some points with a 8-degrees polynom (result of lm is
stored in pfit).
In most of the case, it is ok but for some others, some coefficients are
"NA".
I don't really understand the meaning of these "NA".
And the problem is that I can't perform a derivation
(pderiv<-as.function((deriv(polynomial(pfit$coefficients))))) on pfit due to
the presence of these "NA".
I tried the functions na.omit and na.exclude but "NA" are still there.
I tried to replace manually "NA" by 0. The fit seems ok and then I can
derive the polynom.
But can I do this and, if yes, how can I detect and automatically replace
these "NA" ?
To conclude, I must say that I read some posts on NA but I must confess that
it is still not clear to me (maybe because I'm french and R-newbie ...)
Thanks in advance for your help,
Ptit Bleu.
pfit
Call:
lm(formula = pfitmax ~ poly(vfitmax, 8, raw = T))
Coefficients:
(Intercept) poly(vfitmax, 8, raw = T)1 poly(vfitmax, 8, raw
= T)2 poly(vfitmax, 8, raw = T)3 poly(vfitmax, 8, raw = T)4
-2.790e+04 6.276e+03
-5.645e+02 2.591e+01 -6.241e-01
poly(vfitmax, 8, raw = T)5 poly(vfitmax, 8, raw = T)6 poly(vfitmax, 8, raw
= T)7 poly(vfitmax, 8, raw = T)8
6.681e-03 NA
-3.942e-07 NA
>pderiv<-as.function((deriv(polynomial(pfit$coefficients))))
Erreur dans while ((la <- length(a)) > 1 && a[la] == 0) a <- a[-la] :
valeur manquante là où TRUE / FALSE est requis
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