[R] [BASIC] Solution of creating a sequence of object names
John
cyracules at yahoo.co.uk
Wed Dec 1 19:47:51 CET 2004
Thanks a lot, Adai.
I am sure that your tip is very useful for those who
are not familiar with 'list'.
What is good for using this kind of help list is that
you can learn 'additional' info and tips from 'kind'
users, which you don't usually expect by reading basic
documentations. They are by no means explaining
everything in the best understandable way(in fact,
this is why we have dozens of textbooks in every
subject).
I want to add one more small tip for creating object
names with numbering. I wanted to generate file names
in a following format: 'my01', 'my02', ... , 'my10'.
I used the function, 'formatC', with two arguments
'width' and 'flag'.
Here is the code,
> formatC(99, width=3, flag="0")
[1] "099"
>
> for ( i in 1:10 ) {
+ assign(paste("my", formatC(i, width=2, flag="0"),
sep=""), NULL)
+ }
>
> ls(pat="^my")
[1] "my01" "my02" "my03" "my04" "my05" "my06" "my07"
"my08"
[9] "my09" "my10"
>
But, I do not know if this is covered in basic
documentations and if this is a standard way to do the
job. I'd be interested in learning more about this.
Regards,
John
--- Adaikalavan Ramasamy <ramasamy at cancer.org.uk>
wrote:
> Yes, usability is an important aspect too. For
> programming efficiency
> sake I would suggest a list. Simplified example of
> the 3rd solution (by
> James Holtman) :
>
> mylist <-list(NULL)
> mylist <-list(NULL)
> for(i in 1:3) mylist[[ i ]] <- i
> mylist
> [[1]]
> [1] 1
>
> [[2]]
> [1] 2
>
> [[3]]
> [1] 3
>
>
> Alternative, you can name the indexes
>
> mylist <-list(NULL)
> for(i in 1:3) mylist[[ letters[i] ]] <- i
>
> mylist
> [[1]]
> NULL
>
> $a
> [1] 1
>
> $b
> [1] 2
>
> $c
> [1] 3
>
>
> And these can be called by
>
> mylist$b
> [1] 2
>
> mylist[["c"]]
> [1] 3
>
> Keep in mind that you can put and assign different
> classes into a list
> which makes them very handy.
>
> a <- list(NULL)
> a[[1]] <- "Created on 1st December"
> a[[2]] <- c(1,2,3)
> a[[3]] <- matrix( 1:4, nc=2 )
>
>
>
> On Mon, 2004-11-29 at 22:53, John wrote:
> > It was enough for me to use the 'assign' function
> > alone. But I'll remember the 'get' function for
> future
> > reference. Thanks a lot for the note.
> >
> > John
> >
> >
> > --- bogdan romocea <br44114 at yahoo.com> wrote:
> > > You may be missing something. After you create
> all
> > > those objects,
> > > you'll want to use them. Use get():
> > > for (i in 1:10) ...
> get(paste("object",i,sep=""))
> > > ...
> > > It took me about a week to find out how to do
> this.
> > > I waited for a
> > > few days, but before I got to ask this
> basic/rtfm
> > > question, someone
> > > else - fortunately :-) - did.
> > >
> > > HTH,
> > > b.
> > >
> > >
> > > -----Original Message-----
> > > From: John [mailto:cyracules at yahoo.co.uk]
> > > Sent: Monday, November 29, 2004 4:03 PM
> > > To: r-help at stat.math.ethz.ch
> > > Subject: [R] [BASIC] Solution of creating a
> sequence
> > > of object names
> > >
> > >
> > > Dear R-users,
> > >
> > > I state that this is for beginners, so you may
> > > ignore
> > > this in order not to be irritated.
> > >
> > > By the way, "patience" is another important
> thing,
> > > together with "kindness", we should keep in mind
> > > when
> > > we teach students and our own children as Jim
> Lemon
> > > pointed out well in the context of the Socratic
> > > method. You may know that being kind does not
> mean
> > > giving "spoonfed" answers to questioners.
> > >
> > > ---------------------
> > >
> > > I was asked for the solution of my problem, and
> a
> > > couple of answers were given to me in private
> > > emails.
> > > I am not sure if it was a mere accident. I post
> them
> > > now, without their permission, for those who are
> > > interested in learning them. So if you're happy
> to
> > > know the solution, thanks should go to the
> person
> > > concerned. I thank all the three people named
> below.
> > >
> > > (1) my solution after reading the R-FAQ 7.21 as
> Uwe
> > > Ligges pointed out
> > >
> > > > for ( i in 1:10 ) {
> > > + assign(paste("my.file.", i, sep=""), NULL)
> > > + }
> > > >
> > >
> > > (2) Adai Ramasamy's solution
> > >
> > > > for(obj in paste("my.ftn", 1:10, sep=""))
> > > assign(obj, NULL)
> > > >
> > > ### or
> > > >
> > > > for(i in 1:10) assign(paste("my.ftn", i,
> sep=""),
> > > NULL)
> > > >
> > >
> > > (3) James Holtman's solution
> > >
> > > # For example, if you want to generate 10 groups
>
> > > # of 5 random numbers and store them
> > > # under then names "GRPn" where n is 1 -> 10,
> > > # the following can be used:
> > > #
> > > > Result <- list() # create the list
> > > > for (i in 1:10) Result[[paste("GRP", i,
> sep='')]]
> > > <-
> > > runif(5) # store each result
> > > > Result # print out the data
> > > $GRP1
> > > [1] 0.2655087 0.3721239 0.5728534 0.9082078
> > > 0.2016819
> > >
> > > $GRP2
> > > [1] 0.89838968 0.94467527 0.66079779 0.62911404
> > > 0.06178627
> > >
> > > $GRP3
> > > [1] 0.2059746 0.1765568 0.6870228 0.3841037
> > > 0.7698414
> > >
> > > $GRP4
> > > [1] 0.4976992 0.7176185 0.9919061 0.3800352
> > > 0.7774452
> > >
> > > $GRP5
> > > [1] 0.9347052 0.2121425 0.6516738 0.1255551
> > > 0.2672207
> > >
> > > $GRP6
> > > [1] 0.38611409 0.01339033 0.38238796 0.86969085
> > > 0.34034900
> > >
> > > $GRP7
> > > [1] 0.4820801 0.5995658 0.4935413 0.1862176
> > > 0.8273733
> > >
> > > $GRP8
> > > [1] 0.6684667 0.7942399 0.1079436 0.7237109
> > > 0.4112744
> > >
> > > $GRP9
> > > [1] 0.8209463 0.6470602 0.7829328 0.5530363
> > > 0.5297196
> > >
> > > $GRP10
> > > [1] 0.78935623 0.02333120 0.47723007 0.73231374
> > > 0.69273156
> > >
> > > >
> > >
> > > Regards,
> > >
> > > John
> > >
> > > ______________________________________________
> > > R-help at stat.math.ethz.ch mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-help
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> > >
> > >
> > >
> > >
> > >
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> >
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