itertools2 (version 0.1.1)

iproduct: Iterator that returns the Cartesian product of the arguments.

Description

Constructs an iterator that is the Cartesian product of each of the arguments.

Usage

iproduct(...)

Arguments

...

multiple arguments

Value

iterator that iterates through each element from the Cartesian product

Details

Although they share the same end goal, iproduct can yield drastic memory savings compared to expand.grid.

Examples

it <- iproduct(x=1:3, y=4:5)
iterators::nextElem(it) # list(x=1, y=4)
iterators::nextElem(it) # list(x=1, y=5)
iterators::nextElem(it) # list(x=2, y=4)
iterators::nextElem(it) # list(x=2, y=5)
iterators::nextElem(it) # list(x=3, y=4)
iterators::nextElem(it) # list(x=3, y=5)

# iproduct is a replacement for base::expand.grid()
# Large data.frames are not created unless the iterator is manually consumed
a <- 1:2
b <- 3:4
c <- 5:6
it2 <- iproduct(a=a, b=b, c=c)
df_iproduct <- do.call(rbind, as.list(it2))
df_iproduct <- data.frame(df_iproduct)

# Compare df_iproduct with the results from base::expand.grid()
base::expand.grid(a=a, b=b, c=c)