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Hadley Wickham

2018-Jun-08 15:45 UTC

[Rd] Subsetting the "ROW"s of an object

Hi all,

Is there a better to way to subset the ROWs (in the sense of NROW) of
an vector, matrix, data frame or array than this?

subset_ROW <- function(x, i) {
  nd <- length(dim(x))
  if (nd <= 1L) {
    x[i]
  } else {
    dims <- rep(list(quote(expr = )), nd - 1L)
    do.call(`[`, c(list(quote(x), quote(i)), dims, list(drop = FALSE)))
  }
}

subset_ROW(1:10, 4:6)
#> [1] 4 5 6

str(subset_ROW(array(1:10, c(10)), 2:4))
#>  int [1:3(1d)] 2 3 4
str(subset_ROW(array(1:10, c(10, 1)), 2:4))
#>  int [1:3, 1] 2 3 4
str(subset_ROW(array(1:10, c(5, 2)), 2:4))
#>  int [1:3, 1:2] 2 3 4 7 8 9
str(subset_ROW(array(1:10, c(10, 1, 1)), 2:4))
#>  int [1:3, 1, 1] 2 3 4

subset_ROW(data.frame(x = 1:10, y = 10:1), 2:4)
#>   x y
#> 2 2 9
#> 3 3 8
#> 4 4 7

It seems like there should be a way to do this that doesn't require
generating a call with missing arguments, but I can't think of it.

Thanks!

Hadley

-- 
http://hadley.nz

Iñaki Úcar

2018-Jun-08 17:07 UTC

head link

[Rd] Subsetting the "ROW"s of an object

El vie., 8 jun. 2018 a las 17:46, Hadley Wickham
(<h.wickham at gmail.com>) escribi?:>
> Hi all,
>
> Is there a better to way to subset the ROWs (in the sense of NROW) of
> an vector, matrix, data frame or array than this?
>
> subset_ROW <- function(x, i) {
>   nd <- length(dim(x))
>   if (nd <= 1L) {
>     x[i]
>   } else {
>     dims <- rep(list(quote(expr = )), nd - 1L)
>     do.call(`[`, c(list(quote(x), quote(i)), dims, list(drop = FALSE)))
>   }
> }
>
> subset_ROW(1:10, 4:6)
> #> [1] 4 5 6
>
> str(subset_ROW(array(1:10, c(10)), 2:4))
> #>  int [1:3(1d)] 2 3 4
> str(subset_ROW(array(1:10, c(10, 1)), 2:4))
> #>  int [1:3, 1] 2 3 4
> str(subset_ROW(array(1:10, c(5, 2)), 2:4))
> #>  int [1:3, 1:2] 2 3 4 7 8 9
> str(subset_ROW(array(1:10, c(10, 1, 1)), 2:4))
> #>  int [1:3, 1, 1] 2 3 4
>
> subset_ROW(data.frame(x = 1:10, y = 10:1), 2:4)
> #>   x y
> #> 2 2 9
> #> 3 3 8
> #> 4 4 7
>
> It seems like there should be a way to do this that doesn't require
> generating a call with missing arguments, but I can't think of it.
The following code seems to work. The only minor drawback is that, for
the last case, the output is not a data frame.

subset_ROW <- function(x, i) {
  nd <- length(dim(x))
  if (nd <= 1L)
    return(x[i])
  xx <- apply(x, 2:nd, `[`, i, drop=FALSE)
  dim(xx) <- c(length(i), dim(x)[-1])
  xx
}

I?aki
>
> Thanks!
>
> Hadley
>
> --
> http://hadley.nz
>

Iñaki Úcar

2018-Jun-08 17:09 UTC

head link

[Rd] Subsetting the "ROW"s of an object

Sorry, without remnants from other attempts:

subset_ROW <- function(x, i) {
  nd <- length(dim(x))
  if (nd <= 1L)
    return(x[i])
  apply(x, 2:nd, `[`, i, drop=FALSE)
}
El vie., 8 jun. 2018 a las 19:07, I?aki ?car (<i.ucar86 at gmail.com>)
escribi?:>
> El vie., 8 jun. 2018 a las 17:46, Hadley Wickham
> (<h.wickham at gmail.com>) escribi?:
> >
> > Hi all,
> >
> > Is there a better to way to subset the ROWs (in the sense of NROW) of
> > an vector, matrix, data frame or array than this?
> >
> > subset_ROW <- function(x, i) {
> >   nd <- length(dim(x))
> >   if (nd <= 1L) {
> >     x[i]
> >   } else {
> >     dims <- rep(list(quote(expr = )), nd - 1L)
> >     do.call(`[`, c(list(quote(x), quote(i)), dims, list(drop =
FALSE)))
> >   }
> > }
> >
> > subset_ROW(1:10, 4:6)
> > #> [1] 4 5 6
> >
> > str(subset_ROW(array(1:10, c(10)), 2:4))
> > #>  int [1:3(1d)] 2 3 4
> > str(subset_ROW(array(1:10, c(10, 1)), 2:4))
> > #>  int [1:3, 1] 2 3 4
> > str(subset_ROW(array(1:10, c(5, 2)), 2:4))
> > #>  int [1:3, 1:2] 2 3 4 7 8 9
> > str(subset_ROW(array(1:10, c(10, 1, 1)), 2:4))
> > #>  int [1:3, 1, 1] 2 3 4
> >
> > subset_ROW(data.frame(x = 1:10, y = 10:1), 2:4)
> > #>   x y
> > #> 2 2 9
> > #> 3 3 8
> > #> 4 4 7
> >
> > It seems like there should be a way to do this that doesn't
require
> > generating a call with missing arguments, but I can't think of it.
>
> The following code seems to work. The only minor drawback is that, for
> the last case, the output is not a data frame.
>
> subset_ROW <- function(x, i) {
>   nd <- length(dim(x))
>   if (nd <= 1L)
>     return(x[i])
>   xx <- apply(x, 2:nd, `[`, i, drop=FALSE)
>   dim(xx) <- c(length(i), dim(x)[-1])
>   xx
> }
>
> I?aki
>
> >
> > Thanks!
> >
> > Hadley
> >
> > --
> > http://hadley.nz
> >


-- 
I?aki ?car
http://www.enchufa2.es
@Enchufa2

Michael Lawrence

2018-Jun-08 17:15 UTC

head link

[Rd] Subsetting the "ROW"s of an object

There probably should be an abstraction for this. In S4Vectors, we
have extractROWS().

Michael

On Fri, Jun 8, 2018 at 8:45 AM, Hadley Wickham <h.wickham at gmail.com>
wrote:> Hi all,
>
> Is there a better to way to subset the ROWs (in the sense of NROW) of
> an vector, matrix, data frame or array than this?
>
> subset_ROW <- function(x, i) {
>   nd <- length(dim(x))
>   if (nd <= 1L) {
>     x[i]
>   } else {
>     dims <- rep(list(quote(expr = )), nd - 1L)
>     do.call(`[`, c(list(quote(x), quote(i)), dims, list(drop = FALSE)))
>   }
> }
>
> subset_ROW(1:10, 4:6)
> #> [1] 4 5 6
>
> str(subset_ROW(array(1:10, c(10)), 2:4))
> #>  int [1:3(1d)] 2 3 4
> str(subset_ROW(array(1:10, c(10, 1)), 2:4))
> #>  int [1:3, 1] 2 3 4
> str(subset_ROW(array(1:10, c(5, 2)), 2:4))
> #>  int [1:3, 1:2] 2 3 4 7 8 9
> str(subset_ROW(array(1:10, c(10, 1, 1)), 2:4))
> #>  int [1:3, 1, 1] 2 3 4
>
> subset_ROW(data.frame(x = 1:10, y = 10:1), 2:4)
> #>   x y
> #> 2 2 9
> #> 3 3 8
> #> 4 4 7
>
> It seems like there should be a way to do this that doesn't require
> generating a call with missing arguments, but I can't think of it.
>
> Thanks!
>
> Hadley
>
> --
> http://hadley.nz
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

Berry, Charles

2018-Jun-08 17:16 UTC

head link

[Rd] Subsetting the "ROW"s of an object

> On Jun 8, 2018, at 8:45 AM, Hadley Wickham <h.wickham at gmail.com>
wrote:
> 
> Hi all,
> 
> Is there a better to way to subset the ROWs (in the sense of NROW) of
> an vector, matrix, data frame or array than this?

You can use TRUE to fill the subscripts for dimensions 2:nd
> 
> subset_ROW <- function(x, i) {
>  nd <- length(dim(x))
>  if (nd <= 1L) {
>    x[i]
>  } else {
>    dims <- rep(list(quote(expr = )), nd - 1L)
>    do.call(`[`, c(list(quote(x), quote(i)), dims, list(drop = FALSE)))
>  }
> }

subset_ROW <-
    function(x,i)
{
    mc <- quote(x[i])
    nd <- max(1L, length(dim(x)))
    mc[seq(4, length=nd-1L)] <- rep(list(TRUE), nd - 1L)
    mc[["drop"]] <- FALSE
    eval(mc)
    
}
> 
> subset_ROW(1:10, 4:6)
> #> [1] 4 5 6
> 
> str(subset_ROW(array(1:10, c(10)), 2:4))
> #>  int [1:3(1d)] 2 3 4
> str(subset_ROW(array(1:10, c(10, 1)), 2:4))
> #>  int [1:3, 1] 2 3 4
> str(subset_ROW(array(1:10, c(5, 2)), 2:4))
> #>  int [1:3, 1:2] 2 3 4 7 8 9
> str(subset_ROW(array(1:10, c(10, 1, 1)), 2:4))
> #>  int [1:3, 1, 1] 2 3 4
> 
> subset_ROW(data.frame(x = 1:10, y = 10:1), 2:4)
> #>   x y
> #> 2 2 9
> #> 3 3 8
> #> 4 4 7
> 
HTH,

Chuck

Hadley Wickham

2018-Jun-08 17:29 UTC

head link

[Rd] Subsetting the "ROW"s of an object

I suspect this will have suboptimal performance since the TRUEs will
get recycled. (Maybe there is, or could be, ALTREP, support for
recycling)
Hadley

On Fri, Jun 8, 2018 at 10:16 AM, Berry, Charles <ccberry at ucsd.edu>
wrote:>
>
>> On Jun 8, 2018, at 8:45 AM, Hadley Wickham <h.wickham at
gmail.com> wrote:
>>
>> Hi all,
>>
>> Is there a better to way to subset the ROWs (in the sense of NROW) of
>> an vector, matrix, data frame or array than this?
>
>
> You can use TRUE to fill the subscripts for dimensions 2:nd
>
>>
>> subset_ROW <- function(x, i) {
>>  nd <- length(dim(x))
>>  if (nd <= 1L) {
>>    x[i]
>>  } else {
>>    dims <- rep(list(quote(expr = )), nd - 1L)
>>    do.call(`[`, c(list(quote(x), quote(i)), dims, list(drop = FALSE)))
>>  }
>> }
>
>
> subset_ROW <-
>     function(x,i)
> {
>     mc <- quote(x[i])
>     nd <- max(1L, length(dim(x)))
>     mc[seq(4, length=nd-1L)] <- rep(list(TRUE), nd - 1L)
>     mc[["drop"]] <- FALSE
>     eval(mc)
>
> }
>
>>
>> subset_ROW(1:10, 4:6)
>> #> [1] 4 5 6
>>
>> str(subset_ROW(array(1:10, c(10)), 2:4))
>> #>  int [1:3(1d)] 2 3 4
>> str(subset_ROW(array(1:10, c(10, 1)), 2:4))
>> #>  int [1:3, 1] 2 3 4
>> str(subset_ROW(array(1:10, c(5, 2)), 2:4))
>> #>  int [1:3, 1:2] 2 3 4 7 8 9
>> str(subset_ROW(array(1:10, c(10, 1, 1)), 2:4))
>> #>  int [1:3, 1, 1] 2 3 4
>>
>> subset_ROW(data.frame(x = 1:10, y = 10:1), 2:4)
>> #>   x y
>> #> 2 2 9
>> #> 3 3 8
>> #> 4 4 7
>>
>
> HTH,
>
> Chuck
>


-- 
http://hadley.nz

Hervé Pagès

2018-Jun-08 17:32 UTC

head link

[Rd] Subsetting the "ROW"s of an object

On 06/08/2018 10:15 AM, Michael Lawrence wrote:> There probably should be an abstraction for this. In S4Vectors, we
> have extractROWS().
FWIW the code in S4Vectors that does what your subset_ROW() does is:

 
https://github.com/Bioconductor/S4Vectors/blob/04cc9516af986b30445e99fd1337f13321b7b4f6/R/subsetting-utils.R#L466-L476

(This is the default "extractROWS" method.)

Except for the normalization of 'i', it does the same as your
subset_ROW(). I don't know how to do this without generating a call
with missing arguments.

H.
> 
> Michael
> 
> On Fri, Jun 8, 2018 at 8:45 AM, Hadley Wickham <h.wickham at
gmail.com> wrote:
>> Hi all,
>>
>> Is there a better to way to subset the ROWs (in the sense of NROW) of
>> an vector, matrix, data frame or array than this?
>>
>> subset_ROW <- function(x, i) {
>>    nd <- length(dim(x))
>>    if (nd <= 1L) {
>>      x[i]
>>    } else {
>>      dims <- rep(list(quote(expr = )), nd - 1L)
>>      do.call(`[`, c(list(quote(x), quote(i)), dims, list(drop =
FALSE)))
>>    }
>> }
>>
>> subset_ROW(1:10, 4:6)
>> #> [1] 4 5 6
>>
>> str(subset_ROW(array(1:10, c(10)), 2:4))
>> #>  int [1:3(1d)] 2 3 4
>> str(subset_ROW(array(1:10, c(10, 1)), 2:4))
>> #>  int [1:3, 1] 2 3 4
>> str(subset_ROW(array(1:10, c(5, 2)), 2:4))
>> #>  int [1:3, 1:2] 2 3 4 7 8 9
>> str(subset_ROW(array(1:10, c(10, 1, 1)), 2:4))
>> #>  int [1:3, 1, 1] 2 3 4
>>
>> subset_ROW(data.frame(x = 1:10, y = 10:1), 2:4)
>> #>   x y
>> #> 2 2 9
>> #> 3 3 8
>> #> 4 4 7
>>
>> It seems like there should be a way to do this that doesn't require
>> generating a call with missing arguments, but I can't think of it.
>>
>> Thanks!
>>
>> Hadley
>>
>> --
>>
https://urldefense.proofpoint.com/v2/url?u=http-3A__hadley.nz&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=MF0DzYDiaYtcFXIyQwpQKs9lVbLNvdBBUubTv7BVAfM&s=GSpoAzc1Kn_BnTIkDh0HBFGKtRm-xFodxEPOejriC9Q&e>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=MF0DzYDiaYtcFXIyQwpQKs9lVbLNvdBBUubTv7BVAfM&s=HsEbNAT5IElAUS-W2VVSeJs4tfQc77heV7BbQxru518&e>>
> 
> ______________________________________________
> R-devel at r-project.org mailing list
>
https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=MF0DzYDiaYtcFXIyQwpQKs9lVbLNvdBBUubTv7BVAfM&s=HsEbNAT5IElAUS-W2VVSeJs4tfQc77heV7BbQxru518&e>
-- 
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fredhutch.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319

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