Dear all,
I have divided two vectors:
Np.occup97.98<- as.data.frame(cbind(site = levels(sums$site),
Np.occup97.98 = sums$Ant.Nptrad97.98/Ant.trad$Ant.trad97.98))
> Np.occup97.98
site Np.occup97.98
1 erken97 0.342592592592593
2 erken98 0.333333333333333
3 rormyran 0.48471615720524
4 valkror 0.286026200873362
However, at a later stage of the analysis I want> round(Np.occup97.98[,2], 2)
Error in Math.factor(x, digits) : "round" not meaningful for factors
neither did this work:
> round(Np.occup97.98[,2], 2)
Error in Math.factor(x, digits) : "round" not meaningful for factors
or this:
> round(as.numeric(Np.occup97.98[,2]), 2)
[1] 3 2 4 1>
because, as clearly written in the help file:
"as.numeric for factors yields the codes underlying the factor levels, not
the numeric representation of the labels."
I've discovered this solution:
> Np.occup97.98<- as.data.frame(cbind(site = levels(sums$site),
+ Np.occup97.98
round(sums$Ant.Nptrad97.98/Ant.trad$Ant.trad97.98,2)))>
> Np.occup97.98
site Np.occup97.98
1 erken97 0.34
2 erken98 0.33
3 rormyran 0.48
4 valkror 0.29
However, I would like to do this rounding later.
Could someone give a tip. I think that I would have been helped by a
sentence in help(as.numeric).
Thanks in advance.
Sincerely,
Tord
-----------------------------------------------------------------------
Tord Sn?ll
Avd. f v?xtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
Villav?gen 14
SE-752 36 Uppsala, Sweden
Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
E-mail: Tord.Snall at ebc.uu.se
Check this: http://www.vaxtbio.uu.se/resfold/snall.htm!
You would have been helped by looking in the FAQ: please do so now. Also, ?factor tells you not to use as.numeric. On Thu, 31 Jul 2003, Tord Snall wrote:> Dear all, > > I have divided two vectors: > > Np.occup97.98<- as.data.frame(cbind(site = levels(sums$site), > Np.occup97.98 = sums$Ant.Nptrad97.98/Ant.trad$Ant.trad97.98)) > > > Np.occup97.98 > site Np.occup97.98 > 1 erken97 0.342592592592593 > 2 erken98 0.333333333333333 > 3 rormyran 0.48471615720524 > 4 valkror 0.286026200873362 > > However, at a later stage of the analysis I want > > round(Np.occup97.98[,2], 2) > Error in Math.factor(x, digits) : "round" not meaningful for factors > > neither did this work: > > > round(Np.occup97.98[,2], 2) > Error in Math.factor(x, digits) : "round" not meaningful for factors > > or this: > > > round(as.numeric(Np.occup97.98[,2]), 2) > [1] 3 2 4 1 > > > > because, as clearly written in the help file: > "as.numeric for factors yields the codes underlying the factor levels, not > the numeric representation of the labels." > > I've discovered this solution: > > > Np.occup97.98<- as.data.frame(cbind(site = levels(sums$site), > + Np.occup97.98 > round(sums$Ant.Nptrad97.98/Ant.trad$Ant.trad97.98,2))) > > > > Np.occup97.98 > site Np.occup97.98 > 1 erken97 0.34 > 2 erken98 0.33 > 3 rormyran 0.48 > 4 valkror 0.29 > > > However, I would like to do this rounding later. > > Could someone give a tip. I think that I would have been helped by a > sentence in help(as.numeric). > > > Thanks in advance. > > > Sincerely, > Tord > > > > > ----------------------------------------------------------------------- > Tord Sn?ll > Avd. f v?xtekologi, Evolutionsbiologiskt centrum, Uppsala universitet > Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University > Villav?gen 14 > SE-752 36 Uppsala, Sweden > Tel: 018-471 28 82 (int +46 18 471 28 82) (work) > Tel: 018-25 71 33 (int +46 18 25 71 33) (home) > Fax: 018-55 34 19 (int +46 18 55 34 19) (work) > E-mail: Tord.Snall at ebc.uu.se > Check this: http://www.vaxtbio.uu.se/resfold/snall.htm! > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > >-- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
The problem is that the 2nd column in your data frame has been converted
into a factor. This happened because you used cbind() with mixed character
and numeric vectors. cbind() with these types of arguments will construct
a character matrix. Then when you passed that character matrix to
as.data.frame() it converted both columns to factors.
Here's a simpler example of what happened:
> cbind(letters[1:2], c(1,3))
[,1] [,2]
[1,] "a" "1"
[2,] "b" "3"
> x <- as.data.frame(cbind(letters[1:2], c(1,3)))
> x
V1 V2
1 a 1
2 b 3
> as.numeric(x[,2])
[1] 1 2
> as.numeric(as.character(x[,2]))
[1] 1 3
>
With the data frame as you constructed it, you need an expression like
round(as.numeric(as.character(Np.occup97.98[,2])), 2) to accomplish what
you want. It would probably be better to construct a more felicitous data
frame in the first place:
> df <- data.frame(site = levels(sums$site), Np.occup97.98 =
sums$Ant.Nptrad97.98/Ant.trad$Ant.trad97.98)
(unless of course you had some unstated reason for constructing the data
frame the way you did)
-- Tony Plate
At Thursday 10:03 AM 7/31/2003 +0200, Tord Snall wrote:>Dear all,
>
>I have divided two vectors:
>
>Np.occup97.98<- as.data.frame(cbind(site = levels(sums$site),
> Np.occup97.98 = sums$Ant.Nptrad97.98/Ant.trad$Ant.trad97.98))
>
> > Np.occup97.98
> site Np.occup97.98
>1 erken97 0.342592592592593
>2 erken98 0.333333333333333
>3 rormyran 0.48471615720524
>4 valkror 0.286026200873362
>
>However, at a later stage of the analysis I want
> > round(Np.occup97.98[,2], 2)
>Error in Math.factor(x, digits) : "round" not meaningful for
factors
>
>neither did this work:
>
> > round(Np.occup97.98[,2], 2)
>Error in Math.factor(x, digits) : "round" not meaningful for
factors
>
>or this:
>
> > round(as.numeric(Np.occup97.98[,2]), 2)
>[1] 3 2 4 1
> >
>
>because, as clearly written in the help file:
>"as.numeric for factors yields the codes underlying the factor levels,
not
>the numeric representation of the labels."
>
>I've discovered this solution:
>
> > Np.occup97.98<- as.data.frame(cbind(site = levels(sums$site),
>+ Np.occup97.98
>round(sums$Ant.Nptrad97.98/Ant.trad$Ant.trad97.98,2)))
> >
> > Np.occup97.98
> site Np.occup97.98
>1 erken97 0.34
>2 erken98 0.33
>3 rormyran 0.48
>4 valkror 0.29
>
>
>However, I would like to do this rounding later.
>
>Could someone give a tip. I think that I would have been helped by a
>sentence in help(as.numeric).
>
>
>Thanks in advance.
>
>
>Sincerely,
>Tord
>
>
>
>
>-----------------------------------------------------------------------
>Tord Sn?ll
>Avd. f v?xtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
>Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
>Villav?gen 14
>SE-752 36 Uppsala, Sweden
>Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
>Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
>Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
>E-mail: Tord.Snall at ebc.uu.se
>Check this: http://www.vaxtbio.uu.se/resfold/snall.htm!
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://www.stat.math.ethz.ch/mailman/listinfo/r-help