functional programming - How does the function argument work in R's 'combn'? -

functional programming - How does the function argument work in R's 'combn'? -

despite reading documentation, i'm struggling understand how function argument works in combn utility.

i have table 2 columns of data, each column, want calculate ratio of each unique combination of info pairs in column. let's focus on 1 column simplicity:

v1 1 342.3 2 123.5 3 472.0 4 678.3 ... 14 567.2

i can utilize next homecoming unique combinations:

combn(table[,1], 2)

but of course of study returns each pair of values. want split them ratio, can't seem figure out how set up.

i understand outer, example, can provide operator argument how transfer combn?

combn(table[,1], 2, fun = "/") # not right

the issue function receive 1 parameter. , parameter vector of elements in particular set. / function require 2 separate parameters, not single vector of values. instead write

combn(table[,1], 2, fun = function(x) x[1]/x[2])

so here 1 parameter x , split first value second.

other functions such

combn(1:4, 2, fun = sum)

work fine because expect receive single vector of values.

r functional-programming combinations