Thank you very much !!! It works !!!
Sorry it took me some time to understand your solution and apply it to my
extended dataset. Just got it working !!!
Yes as.numeric is the trick..

Many thanks again for your help and time.

Regards
Meenu

On Sun, Aug 2, 2009 at 6:06 AM, David Winsemius <dwinsemius@comcast.net>wrote:

> Apologies to list: Should have "replied to all".
>
> --
> DW
>
> Begin forwarded message:
>
> > From: David Winsemius <dwinsemius@comcast.net>
> > Date: August 1, 2009 3:02:58 PM EDT
> > To: Meenu Sahi <meenusahi@gmail.com>
> > Subject: Re: [R] Add columns in a dataframe and fill them from
> > another table  according to a criteria
> >
> >
>  > On Aug 1, 2009, at 1:43 PM, Meenu Sahi wrote:
> >
> >> Dear R users
> >> My apologizes for not writing in the correct format due to my
> >> ignorance. In the future I will write more clearly. I hope to
> >> contribute to the R community in the process of picking up the
> >> language professionally.
> >> I have now written the R code which is attached in a notepad file.
> >> I've simplified my problem in an example of, table pstate which
> >> contains the probabilities of getting certain changes in the four
> >> different states and a dataframe mydata4 which contains all the
> >> changes connected to the four different states. I would like to add
> >> the probabilities into mydata4 after matching for the change and
> >> the state.
> >> Everything before ##### output can be copy pasted in the R window.
> >> The desired output is written after ###### OUTPUT
> >> Must I write an if else or can I do it in an easier way?
> >> Your help is greatly appreciated ! Many thanks for your patience.
> >
> > You need to figure out how to send mail to the list with plain text.
> > But I suspect you did successfully get the attchment through to the
> > audience.
> >
> > I did not like the ordering of the PStates in your new target
> > dataframe so I changed it to fit my(and your) purposes.
> >
> > > Change<-c("b","a","b","c","d","a")
> > > State<-c("State1","State4","State2","State3","State1","State3")
> > >
> > > mydata4<-data.frame(Change,State)
> > > mydata4<-data.frame(mydata4,
> > + PState1=NA,
> > + PState2=NA,
> > + PState3=NA,
> > + PState4=NA
> > + )
> > > mydata4
> >  Change  State PState1 PState2 PState3 PState4
> > 1      b State1      NA      NA      NA      NA
> > 2      a State4      NA      NA      NA      NA
> > 3      b State2      NA      NA      NA      NA
> > 4      c State3      NA      NA      NA      NA
> > 5      d State1      NA      NA      NA      NA
> > 6      a State3      NA      NA      NA      NA
> >
> > Note that str(pstate shows that State is a factor which becomes
> > important.
> >
> > This now effects the desired transformation:
> >
> > for (i in 1:length(mydata4) )
> >             {  mydata4[i,  as.numeric( mydata4[i, "State"])+2 ] <-
> >                  #assign to the i-th row, State + 2 column in
> > mydata4 ...
> >              pstate[ mydata4[i, "Change"], as.numeric( mydata4[i,
> > "State"])+1 ] }
> >                   #... the value of i-th row, State+1 column of pstate
> >
> > >  mydata4
> >  Change  State PState1 PState2 PState3 PState4
> > 1      b State1     Pb1    <NA>    <NA>    <NA>
> > 2      a State4    <NA>    <NA>    <NA>     Pa4
> > 3      b State2    <NA>     Pb2    <NA>    <NA>
> > 4      c State3    <NA>    <NA>     Pc3    <NA>
> > 5      d State1     Pd1    <NA>    <NA>    <NA>
> > 6      a State3    <NA>    <NA>     Pa3    <NA>
> >
> > The main non-obvious "trick" is the as.numeric( mydata4[i,
> > "State"])  bit. as.numeric() when applied to a factor results in a
> > numeric offset derived from the factor coding rather than using the
> > level names. I suppose I could have left the PState<n>'s in the
> > original order but then I would have been subtracting them from 7 to
> > get the proper column number. Seemed even less understandable
> >
> >>
> >> Regards
> >> Meenu
> >>
> >> On Sat, Aug 1, 2009 at 9:43 PM, David Winsemius <dwinsemius@comcast.net
> >> > wrote:
> >>
> >> On Aug 1, 2009, at 9:52 AM, Meenu Sahi wrote:
> >>
> >> Deare R users
> >>
> >> I am new to R.
> >> What I want to do is explained below;-
> >> I have table called States.Prob which is given below:-
> >> This table gives the probabilities of the changes in the swap curve
> >> depending on the state of the swap curve. I want to put these
> >> probabilities
> >> in my dataframe mydata(given after the prob table).
> >>               Prob of States
> >> Changes  State1  State2 State3 State4
> >> a             Pa1      Pa2     Pa3     Pa4
> >> b             Pb1      Pb2     Pb3     Pb4
> >> c             Pc1      Pc2     Pc3     Pc4
> >> d             Pd1      Pd2     Pd3     Pd4
> >>
> >> and I have a dataframe(with 93 rows) called mydata part of which(6
> >> rows) is
> >> given below where I want to fill in the last four columns with
> >> probabilities
> >> taken from States.Prob according to the change and state in mydata4:-
> >> Change  State  PState1  PState2  PState3  PState4
> >> 1 b       State1  Pb1
> >> 2 a       State4                                           Pa4
> >> 3 b       State2                Pb2
> >> 4 c       State3                             Pc3
> >> 5 d       State1  Pd1
> >> 6 a       State3                             Pa3
> >>
> >> What I want to do is highlighted in Red.
> >> How can I do this easily?
> >>
> >> You may have seen it in red, but we don't, ....and I, at least,
> >> cannot figure out what you intend.   (Per the Posting Guide, which
> >> you have obviously not yet read, you need to compose your question
> >> in plain old monochromatic text and change your mail client so it
> >> posts in plain text.)
> >>
> >> If looking at the help pages for stack() and reshape() does not
> >> offer useful information and worked examples that meet your needs
> >> then:
> >>
> >> An approach that would make you more populat in these parts would
> >> be to  make a simpler example, composed in syntactically correct R,
> >> that is complete in itself, and can pasted into an R session.
> >> Indicate what you intend as output from this simpler input.
> >>
> >> Perhaps....
> >>
> >> > pstate <- read.table(textConnection("Changes  State1  State2
> >> State3 State4
> >>
> >> + a             Pa1      Pa2     Pa3     Pa4
> >> + b             Pb1      Pb2     Pb3     Pb4
> >> + c             Pc1      Pc2     Pc3     Pc4
> >> + d             Pd1      Pd2     Pd3     Pd4"),  header=TRUE,
> >> as.is=TRUE)
> >>
> >> ?stack
> >>
> >> > data.frame(Change=pstate[,1],
> >>             prstate =stack(pstate[2:5])$values,
> >>             state=stack(pstate[2:5])$ind )
> >>
> >> #first column  is only 4 elements long, but will get recycled
> >> # second  retreives the probabilities and may need to have
> >> as.numeric( ) wrapped around it if they really are numeric.
> >> # third returns what started out as column names.
> >>
> >>  Change prstate  state
> >> 1       a     Pa1 State1
> >> 2       b     Pb1 State1
> >> 3       c     Pc1 State1
> >> 4       d     Pd1 State1
> >> 5       a     Pa2 State2
> >> 6       b     Pb2 State2
> >> 7       c     Pc2 State2
> >> 8       d     Pd2 State2
> >> 9       a     Pa3 State3
> >> 10      b     Pb3 State3
> >> 11      c     Pc3 State3
> >> 12      d     Pd3 State3
> >> 13      a     Pa4 State4
> >> 14      b     Pb4 State4
> >> 15      c     Pc4 State4
> >> 16      d     Pd4 State4
> >>
> >>
> >> Many thanks for your time.
> >>
> >> kind regards
> >> Meenu
> >> P.S. Thanks for your reply John. I've tried to put only the
> >> relevant columns
> >> of the dataframe. Hope its more clear now.
> >>
> >>       \\\\\\\\\\\\\\\\\\//////////////////
> >>       [[alternative HTML version deleted]]
> >>
> >>      ^^^^^^^^^^^^^^Note: ^^^^^^^^^^^^^^^^^^^^^^
> >>
> >> David Winsemius, MD
> >> Heritage Laboratories
> >> West Hartford, CT
> >>
> >>
> >> <Input and Output.txt>
> >
> > David Winsemius, MD
> > Heritage Laboratories
> > West Hartford, CT
> >
>
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-help
>  PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>

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