[R] select if + other questions

[John Kane]

You need to have a look at Chapter 5 of the Intro to
R.   I would recommend downloading the pdf and
printing it out.  It is not an easy read but it should
help.

newdata <- mydata[, c(PUMDID, Y_Q10A)]

or 
newdata <- mydata[, c(1,33)]

should do the trick

--- Natalie O'Toole <notoole at mtroyal.ca> wrote:

> Hi,
> 
> Does anyone know how to skip variables (or columns)
> in R. Say, for example 
> i had PUMFID position1 and Y_Q10A position 33 and i
> do not want to include 
> all the variables in between. Is there a way to do
> this in R when you are 
> extracting variables from a large .txt file with
> many, many variables?
> 
> Thanks,
> 
> Nat
> 
> __________________
> 
> 
> Yes but I believe it will vary depending on what
> package you're using.  I don't deal with weigthed
> data
> so I'm not a good source
> 
> Have a look at help for something like lm in the
> stats
>   package (part of the base installation) for an
> example.
>  
> ?lm 
> 
> weight is the fourth argument down.
> 
> However for more information try
> http://finzi.psych.upenn.edu/search.html and type in
> weight.
> 
> As Brian Ripley says in a reply to a question about
> weights:
>  "Almost all methods I know of do: logistic
> regression, neural nets, classification trees, PPR
> .... "
> 
> 
> --- Natalie O'Toole <notoole at mtroyal.ca> wrote:
> 
> > Hi,
> > 
> > Thank-you for the response!! That worked great!!
> Is
> > there any way to apply 
> > a weight variable to your file similar to what you
> > can do in SPSS? So that 
> > all of your other variables will be weighted by
> the
> > weight variable?
> > 
> > Thanks,
> > 
> > Nat
> > 
> > __________________
> > 
> > 
> > Hi, 
> > 
> > i am trying to read a .txt file, do a couple of
> > select if statements on my 
> > data, and then finally use the ?table function to
> > get frequency counts on 
> > the data. Specifically, i am looking at answering
> > the following question: 
> > 
> > What is the frequency of Grade 7 students in the
> > province of Alberta who 
> > are smokers? 
> > 
> > I am having some problems: 
> > 
> > 1)i cannot get the column names to show up when
> > print to screen 
> > 
> > 2)I cannot seem to skip variables properly when i
> > choose certain other 
> > variables 
> > 
> > 3)i cannot get the combination of Select If
> > statements to work to produce 
> > a different table with my new criteria
> > 
> > Here are the variables 
> > 
> > PUMFID position1 length 5 
> > PROV position 6 length 2 
> > GRADE position 9 length 2 
> > Y_Q10A position 33 length 1 
> > 
> > 
> > Y_Q10A has the following 1=yes 
> >                            2=no
> >                           9=skip 
> > 
> > all the others have no skipped or missing values 
> > 
> > Here is my code: 
> > 
> > myfile<-("c:/test2.txt") 
> >
> myVariableNames<-c("PUMFID","PROV","GRADE","Y_Q10A")
> > 
> > myVariableWidths<-c(5,2,2,1) 
> > 
> > 
> >  mydata<-read.fwf( 
> > file=myfile, 
> > width=myVariableWidths, 
> > col.names=myVariableNames, 
> > row.names="PUMFID", 
> > fill=TRUE, 
> > strip.white=TRUE) 
> > 
> > 
> > print(mydata) 
> > 
> > print( mydata [which(PROV=="AB" & GRADE==7 &
> > Y_Q10A<9), ] ) 
> > 
> > 
> > 
> > Any help would be greatly appreciated!! 
> > 
> > Thank-you, 
> > 
> > Nat 
> > 
> >
>
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