Hi Bert,
I really liked your solution.
In the spirit of code golf, I wondered if there is a shorter way to do
the regular expression test.
Kudos to my coding buddy GPT-4 for the following:
You can replace your statement
out[-grep(paste(paste0(states,states), collapse = "|"),out)]
by
out[-grep("(.)\\1",out)]
Best,
Eric
On Tue, Sep 5, 2023 at 3:08?AM Bert Gunter <bgunter.4567 at gmail.com>
wrote:>
> ... and just for fun, here is a non-string version (more appropriate for
complex state labels??):
>
> gvec <- function(ntimes, states, init, final, repeats = TRUE)
> ## ntimes: integer, number of unique times
> ## states: vector of unique states
> ## init: initial state
> ## final: final state
> {
> out <- cbind(init,
> as.matrix(expand.grid(rep(list(states),ntimes -2 ))),final)
> if(!repeats)
> out[ apply(out,1,\(x)all(x[-1] != x[-ntimes])), ]
> else out
> }
>
> yielding:
>
>
> > gvec(4, letters[1:5], "b", "e", repeats = TRUE)
> init Var1 Var2 final
> [1,] "b" "a" "a" "e"
> [2,] "b" "b" "a" "e"
> [3,] "b" "c" "a" "e"
> [4,] "b" "d" "a" "e"
> [5,] "b" "e" "a" "e"
> [6,] "b" "a" "b" "e"
> [7,] "b" "b" "b" "e"
> [8,] "b" "c" "b" "e"
> [9,] "b" "d" "b" "e"
> [10,] "b" "e" "b" "e"
> [11,] "b" "a" "c" "e"
> [12,] "b" "b" "c" "e"
> [13,] "b" "c" "c" "e"
> [14,] "b" "d" "c" "e"
> [15,] "b" "e" "c" "e"
> [16,] "b" "a" "d" "e"
> [17,] "b" "b" "d" "e"
> [18,] "b" "c" "d" "e"
> [19,] "b" "d" "d" "e"
> [20,] "b" "e" "d" "e"
> [21,] "b" "a" "e" "e"
> [22,] "b" "b" "e" "e"
> [23,] "b" "c" "e" "e"
> [24,] "b" "d" "e" "e"
> [25,] "b" "e" "e" "e"
> >
> > gvec(4, letters[1:5], "b", "e", repeats = FALSE)
> init Var1 Var2 final
> [1,] "b" "c" "a" "e"
> [2,] "b" "d" "a" "e"
> [3,] "b" "e" "a" "e"
> [4,] "b" "a" "b" "e"
> [5,] "b" "c" "b" "e"
> [6,] "b" "d" "b" "e"
> [7,] "b" "e" "b" "e"
> [8,] "b" "a" "c" "e"
> [9,] "b" "d" "c" "e"
> [10,] "b" "e" "c" "e"
> [11,] "b" "a" "d" "e"
> [12,] "b" "c" "d" "e"
> [13,] "b" "e" "d" "e"
>
> :-)
>
> -- Bert
>
> On Mon, Sep 4, 2023 at 2:04?PM Bert Gunter <bgunter.4567 at
gmail.com> wrote:
>>
>> Well, if strings with repeats (as you defined them) are to be excluded,
I think it's simple just to use regular expressions to remove them.
>>
>> e.g.
>> g <- function(ntimes, states, init, final, repeats = TRUE)
>> ## ntimes: integer, number of unique times
>> ## states: vector of unique states
>> ## init: initial state
>> ## final: final state
>> {
>> out <- do.call(paste0,c(init,expand.grid(rep(list(states),
ntimes-2)), final))
>> if(!repeats)
>> out[-grep(paste(paste0(states,states), collapse =
"|"),out)]
>> else out
>> }
>> So:
>>
>> > g(4, LETTERS[1:5], "B", "E", repeats = FALSE)
>> [1] "BCAE" "BDAE" "BEAE"
"BABE" "BCBE" "BDBE" "BEBE"
"BACE"
>> [9] "BDCE" "BECE" "BADE"
"BCDE" "BEDE"
>>
>> Perhaps not the most efficient way to do this, of course.
>>
>> Cheers,
>> Bert
>>
>>
>> On Mon, Sep 4, 2023 at 12:57?PM Eric Berger <ericjberger at
gmail.com> wrote:
>>>
>>> My initial response was buggy and also used a deprecated function.
>>> Also, it seems possible that one may want to rule out any strings
where the same state appears consecutively.
>>> I say that such a string has a repeat.
>>>
>>> myExpand <- function(v, n) {
>>> do.call(tidyr::expand_grid, replicate(n, v, simplify = FALSE))
>>> }
>>>
>>> no_repeat <- function(s) {
>>> v <- unlist(strsplit(s, NULL))
>>> sum(v[-1]==v[-length(v)]) == 0
>>> }
>>>
>>> f <- function(states, nsteps, first, last, rm_repeat=TRUE) {
>>> if (nsteps < 3) stop("nsteps must be at least 3")
>>> out <- paste(first,
>>> myExpand(states, nsteps-2) |>
>>> apply(MAR=1, \(x) paste(x, collapse="")),
>>> last, sep="")
>>> if (rm_repeat) {
>>> ok <- sapply(out, no_repeat)
>>> out <- out[ok]
>>> }
>>> out
>>> }
>>>
>>> f(LETTERS[1:5],4,"B","E")
>>>
>>> # [1] "BABE" "BACE" "BADE"
"BCAE" "BCBE" "BCDE" "BDAE"
"BDBE" "BDCE" "BEAE" "BEBE"
"BECE" "BEDE"
>>>
>>> On Mon, Sep 4, 2023 at 10:33?PM Bert Gunter <bgunter.4567 at
gmail.com> wrote:
>>>>
>>>> Sorry, my last line should have read:
>>>>
>>>> If neither this nor any of the other suggestions is what is
desired, I think the OP will have to clarify his query.
>>>>
>>>> Bert
>>>>
>>>> On Mon, Sep 4, 2023 at 12:31?PM Bert Gunter <bgunter.4567 at
gmail.com> wrote:
>>>>>
>>>>> I think there may be some uncertainty here about what the
OP requested. My interpretation is:
>>>>>
>>>>> n different times
>>>>> k different states
>>>>> Any state can appear at any time in the vector of times and
can be repeated
>>>>> Initial and final states are given
>>>>>
>>>>> So modifying Tim's expand.grid() solution a bit yields:
>>>>>
>>>>> g <- function(ntimes, states, init, final){
>>>>> ## ntimes: integer, number of unique times
>>>>> ## states: vector of unique states
>>>>> ## init: initial state
>>>>> ## final: final state
>>>>> do.call(paste0,c(init,expand.grid(rep(list(states),
ntimes-2)), final))
>>>>> }
>>>>>
>>>>> e.g.
>>>>>
>>>>> > g(4, LETTERS[1:5], "B", "D")
>>>>> [1] "BAAD" "BBAD" "BCAD"
"BDAD" "BEAD" "BABD" "BBBD"
"BCBD"
>>>>> [9] "BDBD" "BEBD" "BACD"
"BBCD" "BCCD" "BDCD" "BECD"
"BADD"
>>>>> [17] "BBDD" "BCDD" "BDDD"
"BEDD" "BAED" "BBED" "BCED"
"BDED"
>>>>> [25] "BEED"
>>>>>
>>>>> If neither this nor any of the other suggestions is not
what is desired, I think the OP will have to clarify his query.
>>>>>
>>>>> Cheers,
>>>>> Bert
>>>>>
>>>>> On Mon, Sep 4, 2023 at 9:25?AM Ebert,Timothy Aaron
<tebert at ufl.edu> wrote:
>>>>>>
>>>>>> Does this work for you?
>>>>>>
>>>>>> t0<-t1<-t2<-LETTERS[1:5]
>>>>>> al2<-expand.grid(t0, t1, t2)
>>>>>> al3<-paste(al2$Var1, al2$Var2, al2$Var3)
>>>>>> al4 <- gsub(" ", "", al3)
>>>>>> head(al3)
>>>>>>
>>>>>> Tim
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: R-help <r-help-bounces at r-project.org> On
Behalf Of Eric Berger
>>>>>> Sent: Monday, September 4, 2023 10:17 AM
>>>>>> To: Christofer Bogaso <bogaso.christofer at
gmail.com>
>>>>>> Cc: r-help <r-help at r-project.org>
>>>>>> Subject: Re: [R] Finding combination of states
>>>>>>
>>>>>> [External Email]
>>>>>>
>>>>>> The function purrr::cross() can help you with this. For
example:
>>>>>>
>>>>>> f <- function(states, nsteps, first, last) {
>>>>>> paste(first,
unlist(lapply(purrr::cross(rep(list(v),nsteps-2)),
>>>>>> \(x) paste(unlist(x), collapse=""))), last,
sep="") } f(LETTERS[1:5], 3, "B", "E") [1]
"BAE" "BBE" "BCE" "BDE" "BEE"
>>>>>>
>>>>>> HTH,
>>>>>> Eric
>>>>>>
>>>>>>
>>>>>> On Mon, Sep 4, 2023 at 3:42?PM Christofer Bogaso
<bogaso.christofer at gmail.com> wrote:
>>>>>> >
>>>>>> > Let say I have 3 time points.as T0, T1, and
T2.(number of such time
>>>>>> > points can be arbitrary) In each time point, an
object can be any of 5
>>>>>> > states, A, B, C, D, E (number of such states can
be arbitrary)
>>>>>> >
>>>>>> > I need to find all possible ways, how that object
starting with state
>>>>>> > B (say) at time T0, can be on state E (example) in
time T2
>>>>>> >
>>>>>> > For example one possibility is BAE etc.
>>>>>> >
>>>>>> > Is there any function available with R, that can
give me a vector of
>>>>>> > such possibilities for arbitrary number of states,
time, and for a
>>>>>> > given initial and final (desired) states?
>>>>>> >
>>>>>> > ANy pointer will be very appreciated.
>>>>>> >
>>>>>> > Thanks for your time.
>>>>>> >
>>>>>> > ______________________________________________
>>>>>> > R-help at r-project.org mailing list -- To
UNSUBSCRIBE and more, see
>>>>>> > https://stat/
>>>>>> >
.ethz.ch%2Fmailman%2Flistinfo%2Fr-help&data=05%7C01%7Ctebert%40ufl.edu
>>>>>> >
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>>>>>> >
%7C0%7C0%7C638294338934034595%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAw
>>>>>> >
MDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sda
>>>>>> >
ta=TM4jGF39Gy3PH0T3nnQpT%2BLogkVxifv%2Fudv9hWPwbss%3D&reserved=0
>>>>>> > PLEASE do read the posting guide
>>>>>> > http://www.r/
>>>>>> >
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>>>>>> >
cee5ce26a8423daaa508dbad51c402%7C0d4da0f84a314d76ace60a62331e1b84%7C0%
>>>>>> >
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>>>>>> >
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>>>>>> >
PTLmsz0lOz47t41u578t9oI0i7BOgIX53yx8CesLs%3D&reserved=0
>>>>>> > and provide commented, minimal, self-contained,
reproducible code.
>>>>>>
>>>>>> ______________________________________________
>>>>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE
and more, see
>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>>> PLEASE do read the posting guide
http://www.r-project.org/posting-guide.html
>>>>>> and provide commented, minimal, self-contained,
reproducible code.
>>>>>> ______________________________________________
>>>>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE
and more, see
>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>>> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>>>>>> and provide commented, minimal, self-contained,
reproducible code.