[R] Problem with if statement

[Gabor Grothendieck]

It would be easier to answer if a portion of the input were shown in
the question using dput(rf) or dput(head(rf)) but lets assume it looks
like this and that our objective is to display a table of Name vs.
DNAME counts where DNAME consists of manufactured short names  -- is
that right?

DF <- data.frame(ID = c(10, 20, 10), Name = c("A blah", "B blah", "A blah"))

# Then here are several alternatives:

# 1. using assignment as in original question
DF1 <- DF
DF1$DNAME[DF1$ID == 10] <- "A"
DF1$DNAME[DF1$ID == 20] <- "B"
with(DF1, table(Name, DNAME))

# 2. using ifelse
DF2 <- DF
DF$NAME <- ifelse(DF2$ID == 10, "A", "B")

# 3. using sub assuming first word is unique
DF3 <- transform(DF, DNAME = sub(" .*", "", Name))
with(DF3, table(Name, DNAME))

# 4. using abbreviate although abbreviated names do not always look nice
DF4 <- transform(DF, DNAME = abbreviate(Name))
with(DF4, table(Name, DNAME))

# 5. subscripting by name
shortNames <- c("A blah" = "A", "B blah" = "B")
DF5 <- transform(DF, DNAME = shortNames[Name])
with(DF5, table(Name, DNAME))


On Tue, Dec 8, 2009 at 7:45 PM, Arthur Burke
<Art.Burke at educationnorthwest.org> wrote:
> I am trying to use the value of an ID variable in an if statement and
> not getting the results I expected.
>
> # ID values for two school districts
>> with(rf, tapply(DistrictID, DistrictName, min) )
>
> Aberdeen School Dist. # 58         Buhl Joint School District
>                             59340                              53409
>
>
> This creates DNAME as I expected ...
>
> rf$DNAME[rf$DistrictID==59340] <- 'Aberdeen'
> rf$DNAME[rf$DistrictID==53409] <- 'Buhl'
>
>
>> with(rf, table(DistrictName, DNAME) )
>                                    DNAME
> DistrictName                         Aberdeen Buhl
>  Aberdeen School Dist. # 58              242    0
>  Buhl Joint School District                0  428
>
> But these if statements ...
>
> if(rf$DistrictID == 59340) {rf$D.NAME <- 'Aberdeen'}
> if(rf$DistrictID == 53409) {rf$D.NAME <- 'Buhl'}
>
>
> Lead to this ...
>
> with(rf, table(DistrictName, D.NAME) )
>
>                                    D.NAME
> DistrictName                         Aberdeen
>  Aberdeen School Dist. # 58              242
>  Buhl Joint School District              428
>
>
> What am I doing wrong in the if statement?
>
> Thanks!
> Art
>
> *************************
>
> Art Burke
>
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>
> Education Northwest
>
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