[R] ifelse() question
F Z
gerifalte28 at hotmail.com
Sat Oct 30 00:08:24 CEST 2004
Many thanks to Peter, Sundar and Adaikalavan for their useful help. As
Adaikalavan correctly pointed out, the key was to pass as.character() as an
argument within the ifelse() function. Here is the soution using a subset
of my data:
dat[1:10,]
id long lat species type size
1 91029 -95.29819 46.41441 BOV FRM NA
2 13468 -95.09137 46.26823 POR FP 0
3 92511 -95.29784 44.47016 BOV FRM NA
4 30312 -94.97496 44.41489 POR FTF 120
5 90275 -93.73471 44.92226 BOV FRM NA
6 38367 -95.54004 44.02396 POR FF NA
7 90460 -94.34028 44.89793 BOV FRM NA
8 38564 -93.51084 43.65327 OVI CL 75
9 33532 -93.06094 45.76132 POR FTF NA
10 11860 -95.23439 45.21244 POR FP 0
test<-dat[1:10,]
attach(test)
test[,4]<-ifelse(species=="POR",as.character(type),as.character(species))
test
id long lat species type size
1 91029 -95.29819 46.41441 BOV FRM NA
2 13468 -95.09137 46.26823 FP FP 0
3 92511 -95.29784 44.47016 BOV FRM NA
4 30312 -94.97496 44.41489 FTF FTF 120
5 90275 -93.73471 44.92226 BOV FRM NA
6 38367 -95.54004 44.02396 FF FF NA
7 90460 -94.34028 44.89793 BOV FRM NA
8 38564 -93.51084 43.65327 OVI CL 75
9 33532 -93.06094 45.76132 FTF FTF NA
10 11860 -95.23439 45.21244 FP FP 0
It worked! Now all the species =="POR" were replaced by the adjacent value
on the column type.
Thanks again!
Francisco
>From: Adaikalavan Ramasamy <ramasamy at cancer.org.uk>
>Reply-To: ramasamy at cancer.org.uk
>To: F Z <gerifalte28 at hotmail.com>
>CC: R-help <r-help at stat.math.ethz.ch>
>Subject: Re: [R] ifelse() question
>Date: Fri, 29 Oct 2004 18:44:06 +0100
>
>Francisco, a more reproducible example would have helped but see if the
>following helps in your understanding
>
># Create dataset
>
>df <- data.frame( type=1:5, species=LETTERS[1:5] )
>df
> type species
> 1 1 A
> 2 2 B
> 3 3 C
> 4 4 D
> 5 5 E
>
>df[ ,2] == "E"
> [1] FALSE FALSE FALSE FALSE TRUE
>
># Note that you need to coerce as.character inside ifelse
>attach(df)
>(df[ ,2] <- ifelse( species == "E", type, as.character(species) ))
> [1] "A" "B" "C" "D" "5"
>detach(df)
>
>df
> type species
> 1 1 A
> 2 2 B
> 3 3 C
> 4 4 D
> 5 5 5
>
>
>On Fri, 2004-10-29 at 18:03, F Z wrote:
> > Thanks for you reply Peter. I tried using as.character and then
>converting
> > to factors but it did not work since it generates missing values for all
>the
> > dat[,4]=="POR". See:
> >
> > >dat[1:5,4]
> > [1] BOV POR BOV POR BOV
> > Levels: BOV CAP CER OVI POR
> >
> > test<-dat
> >
> > >test[,4]<-as.character(test[,4])
> > >test[,5]<-as.character(test[,5])
> > >test[test[,4]=="POR",4]<-test[test[,4]=="POR",5]
> > Error in "[<-.data.frame"(`*tmp*`, test[, 4] == "POR", 4, value = c(NA,
>:
> > missing values are not allowed in subscripted assignments of
>data
> > frames
> > >test[,4]<-as.factor(test[,4])
> > >test[,5]<-as.factor(test[,5])
> >
> > >test[1:5,4]
> > [1] BOV <NA> BOV <NA> BOV
> > Levels: BOV CAP CER OVI
> >
> >
> > Any suggestions?
> >
> > Thanks again!
> >
> > Francisco
> >
> >
> > >From: "Peter Alspach" <PAlspach at hortresearch.co.nz>
> > >To: <gerifalte28 at hotmail.com>,<R-help at stat.math.ethz.ch>
> > >Subject: Re: [R] ifelse() question
> > >Date: Fri, 29 Oct 2004 13:33:54 +1300
> > >
> > >
> > >Francisco
> > >
> > >Did you try changing the factors to character, with as.character?
> > >
> > >Also you don't really need ifelse() for this. Something like the
> > >following (untested) should do it:
> > >
> > >dat[,4] <- as.character(dat[,4])
> > >dat[,5] <- as.character(dat[,5])
> > >dat[dat[,4]=='POR',4] <- dat[dat[,4]=='POR',5]
> > >dat[,4] <- as.factor(dat[,4])
> > >dat[,5] <- as.factor(dat[,5])
> > >
> > >
> > >Peter Alspach
> > >
> > > >>> "F Z" <gerifalte28 at hotmail.com> 29/10/04 12:48:54 >>>
> > >Hi
> > >
> > >I have a data.frame with dim = 18638 (rows) 6 (cols)
> > >
> > >names(dat)
> > >[1] "id" "long" "lat" "species" "type" "size"
> > >
> > >Variable "species" and "type" are factors. Species has 5 levels "BOV"
> > >"CAP"
> > >"CER" "OVI" "POR"
> > >Variable "type" has 11 levels "BRD" "CL" ... "OTHER"
> > >
> > >I would like to replace the values on species by the values on types
> > >only if
> > >species is == "POR"
> > >I tried:
> > >
> > >x<-ifelse(dat$species %in% "POR",dat$type,dat$species)
> > >dat[,4]<-x
> > >but levels(x)
> > >[1] "1" "2" "3" "4" "5" "6" "8" "9" "10" "11" "12"
> > >
> > >So x changes the factor names by numbers. I can not use factor() to
> > >recover
> > >the names since the resulting factors in x are a mixture of factors
> > >from
> > >species and type.
> > >
> > >I also tried
> > >
> > >x<-gsub(pattern = "POR",replacement= factor(dat$type),dat$species)
> > >with
> > >same behavior.
> > >
> > >Apparently I did not have my granola bar today so I can't find a
> > >solution!
> > >Any help is greatly appreciated
> > >
> > >Thanks!
> > >
> > >Francisco
> > >
> > >______________________________________________
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