Manipulating Arrays
Using the below data:
df <- structure(list(dim1 = structure(c(1L, 3L, 1L, 4L, 1L, 2L, 2L,
2L, 3L, 1L, 4L, 3L, 4L, 4L, 3L, 2L), .Label = c("a1", "a2",
"a3",
"a4"), class = "factor"), dim2 = structure(c(2L, 1L, 2L, 2L,
4L, 3L, 1L, 3L, 1L, 3L, 2L, 4L, 3L, 4L, 1L, 4L), .Label = c("b1",
"b2", "b3", "b4"), class = "factor"),
dim3 = structure(c(1L,
4L, 3L, 2L, 1L, 1L, 2L, 4L, 3L, 2L, 2L, 3L, 3L, 1L, 4L, 4L), .Label
c("c1",
"c2", "c3", "c4"), class = "factor"),
dim4 = structure(c(2L,
4L, 1L, 3L, 3L, 1L, 2L, 2L, 3L, 2L, 3L, 4L, 1L, 4L, 1L, 4L), .Label
c("d1",
"d2", "d3", "d4"), class = "factor"),
value = c(33L, 28L, 97L,
64L, 95L, 64L, 21L, 76L, 93L, 50L, 30L, 7L, 89L, 57L, 27L, 14L
)), .Names = c("dim1", "dim2", "dim3",
"dim4", "value"), class "data.frame", row.names =
c(NA,
-16L))
library(reshape)
arr <- cast(df, dim1~dim2~dim3~dim4, sum)
> dim(arr)
[1] 4 4 4 4
How do I manipulate this array?
1. Can I add an extra element in the first dimension using the existing
dimensions? As in a dataframe? Such as (The below does not work)
> arr[5,,,] <- arr[1,,,] * 2 + 1
Error in arr[5, , , ] <- arr[1, , , ] * 2 + 1 : subscript out of bounds
2. How do I remove say the 2 element of the first dimension and have other
elements re-arranged in the logical way
i.e deleting arr[2,,,] means arr[3,,,] becomes arr[2,,,]; and arr[4,,,]
becomes arr[3,,,]
(again the below does not work)
arr[2,,,] <- NULL
Error in arr[2, , , ] <- NULL :
number of items to replace is not a multiple of replacement length
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Hi, the abind package can help you with the first query, ## add values library(abind) arr <- abind(arr,arr[1,,,] * 2 + 1,along=1) dim(arr) as for the second, maybe you can use negative indexing, ## remove values arr <- arr[-2,,,] HTH, baptiste 2009/10/11 ampc <ampc2008 at gmail.com>:> > Manipulating Arrays > Using the below data: > > df <- structure(list(dim1 = structure(c(1L, 3L, 1L, 4L, 1L, 2L, 2L, > 2L, 3L, 1L, 4L, 3L, 4L, 4L, 3L, 2L), .Label = c("a1", "a2", "a3", > "a4"), class = "factor"), dim2 = structure(c(2L, 1L, 2L, 2L, > 4L, 3L, 1L, 3L, 1L, 3L, 2L, 4L, 3L, 4L, 1L, 4L), .Label = c("b1", > "b2", "b3", "b4"), class = "factor"), dim3 = structure(c(1L, > 4L, 3L, 2L, 1L, 1L, 2L, 4L, 3L, 2L, 2L, 3L, 3L, 1L, 4L, 4L), .Label > c("c1", > "c2", "c3", "c4"), class = "factor"), dim4 = structure(c(2L, > 4L, 1L, 3L, 3L, 1L, 2L, 2L, 3L, 2L, 3L, 4L, 1L, 4L, 1L, 4L), .Label > c("d1", > "d2", "d3", "d4"), class = "factor"), value = c(33L, 28L, 97L, > 64L, 95L, 64L, 21L, 76L, 93L, 50L, 30L, 7L, 89L, 57L, 27L, 14L > )), .Names = c("dim1", "dim2", "dim3", "dim4", "value"), class > "data.frame", row.names = c(NA, > -16L)) > > library(reshape) > arr <- cast(df, dim1~dim2~dim3~dim4, sum) > >> dim(arr) > [1] 4 4 4 4 > > How do I manipulate this array? > > > 1. Can I add an extra element in the first dimension using the existing > dimensions? As in a dataframe? Such as (The below does not work) > >> arr[5,,,] <- arr[1,,,] * 2 + 1 > Error in arr[5, , , ] <- arr[1, , , ] * 2 + 1 : subscript out of bounds > > 2. How do I remove say the 2 element of the first dimension and have other > elements re-arranged in the logical way > i.e deleting arr[2,,,] means arr[3,,,] becomes arr[2,,,]; and arr[4,,,] > becomes arr[3,,,] > (again the below does not work) > arr[2,,,] <- NULL > > Error in arr[2, , , ] <- NULL : > ?number of items to replace is not a multiple of replacement length > > > -- > View this message in context: http://www.nabble.com/Manipulating-Arrays-tp25838608p25838608.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > 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. >
Thanks baptiste. Works as expected. ampy ampc wrote:> > Manipulating Arrays > Using the below data: > > df <- structure(list(dim1 = structure(c(1L, 3L, 1L, 4L, 1L, 2L, 2L, > 2L, 3L, 1L, 4L, 3L, 4L, 4L, 3L, 2L), .Label = c("a1", "a2", "a3", > "a4"), class = "factor"), dim2 = structure(c(2L, 1L, 2L, 2L, > 4L, 3L, 1L, 3L, 1L, 3L, 2L, 4L, 3L, 4L, 1L, 4L), .Label = c("b1", > "b2", "b3", "b4"), class = "factor"), dim3 = structure(c(1L, > 4L, 3L, 2L, 1L, 1L, 2L, 4L, 3L, 2L, 2L, 3L, 3L, 1L, 4L, 4L), .Label > c("c1", > "c2", "c3", "c4"), class = "factor"), dim4 = structure(c(2L, > 4L, 1L, 3L, 3L, 1L, 2L, 2L, 3L, 2L, 3L, 4L, 1L, 4L, 1L, 4L), .Label > c("d1", > "d2", "d3", "d4"), class = "factor"), value = c(33L, 28L, 97L, > 64L, 95L, 64L, 21L, 76L, 93L, 50L, 30L, 7L, 89L, 57L, 27L, 14L > )), .Names = c("dim1", "dim2", "dim3", "dim4", "value"), class > "data.frame", row.names = c(NA, > -16L)) > > library(reshape) > arr <- cast(df, dim1~dim2~dim3~dim4, sum) > >> dim(arr) > [1] 4 4 4 4 > > How do I manipulate this array? > > > 1. Can I add an extra element in the first dimension using the existing > dimensions? As in a dataframe? Such as (The below does not work) > >> arr[5,,,] <- arr[1,,,] * 2 + 1 > Error in arr[5, , , ] <- arr[1, , , ] * 2 + 1 : subscript out of bounds > > 2. How do I remove say the 2 element of the first dimension and have other > elements re-arranged in the logical way > i.e deleting arr[2,,,] means arr[3,,,] becomes arr[2,,,]; and arr[4,,,] > becomes arr[3,,,] > (again the below does not work) > arr[2,,,] <- NULL > > Error in arr[2, , , ] <- NULL : > number of items to replace is not a multiple of replacement length > > >-- View this message in context: http://www.nabble.com/Manipulating-Arrays-tp25838608p25846594.html Sent from the R help mailing list archive at Nabble.com.