This package provides consistent utility functions for array programming with arbitrary dimensions (summary below).
We recommend to load this package in its own namespace to not shadow base R functions using modules
or import
.
# example referencing the package namespace
# do not load the package with 'library(...)' here
::stack(...) narray
stack()
is like cbind
/rbind
, but along arbitrary axes, and taking care of (1) names along each dimension and (2) padding partial matching arrays.
= matrix(1:4, nrow=2, ncol=2, dimnames=list(c('a','b'),c('x','y')))
A = matrix(5:6, nrow=2, ncol=1, dimnames=list(c('b','a'),'z'))
B
= stack(A, B, along=2)
C C
## x y z
## a 1 3 6
## b 2 4 5
= stack(m=A, n=C, along=3) # we can also introduce new dimensions
D D
## , , m
##
## x y z
## a 1 3 NA
## b 2 4 NA
##
## , , n
##
## x y z
## a 1 3 6
## b 2 4 5
split()
splits an array along a given axis; can do each element or defined subsets.
split(C, along=2, subsets=c('s1','s1','s2'))
## $s1
## x y
## a 1 3
## b 2 4
##
## $s2
## z
## a 6
## b 5
Like apply
, but not reordering array dimensions and allowing to specify subsets that the function should be applied on. The function must either return a vector of the same length as the input (returns matrix of same dimension) or of length 1 (drops current dimension or returns subsets).
map(C, along=2, function(x) x*2) # return same length vector
## x y z
## a 2 6 12
## b 4 8 10
map(C, along=2, mean, subsets=c('s1', 's1', 's2')) # summarize each subset to scalar
## s1 s2
## a 2 6
## b 3 5
We can also index multiple arrays using the lambda
function. If the result is a scalar we will get back an array, and an index with result column otherwise.
= function(x, y) sum(x * y)
dot lambda(~ dot(A, B), along=c(A=1, B=2))
## B
## A z
## a 23
## b 34
lambda(~ dot(A, B), along=c(A=1, B=2), simplify=FALSE)
## A B result
## 1 a z 23
## 2 b z 34
Takes a number of arrays, intersects their names along a given dimension, and returns sub-arrays that match in their names; intersect_list
takes a list of arrays and returns a list of subsets.
= matrix(1:6, nrow=3, dimnames=list(c('a','b','d'), c('x','y')))
E = matrix(7:9, nrow=3, dimnames=list(c('b','a','c'), 'z'))
F
intersect(E, F, along=1)
E
## x y
## a 1 4
## b 2 5
F
## z
## a 8
## b 7
data.frame
sconstruct()
takes a data frame and a formula specifying dependent (values) and independent (axes) of the resulting array.
= data.frame(k1=base::rep(letters[1:3],2),
DF k2=base::rep(letters[24:25],3), v=1:6)[-6,]
construct(v ~ k1 + k2, data=DF)
## k2
## k1 x y
## a 1 4
## b 5 2
## c 3 NA
Takes either a factor or a list of vectors and creates a binary matrix specifying whether each element is present.
= list(a='e1', b=c('e1','e2'), c='e2')
G mask(G)
## e1 e2
## a TRUE FALSE
## b TRUE TRUE
## c FALSE TRUE