Understand the `Reduce` function

Question

I have a question about the Reduce function in R. I read its documentation, but I am still confused a bit. So, I have 5 vectors with genes name. For example:

Answer 1

A nice way to see what Reduce() is doing is to run it with its argument accumulate=TRUE. When accumulate=TRUE, it will return a vector or list in which each element shows its state after processing the first n elements of the list in x. Here are a couple of examples:

Reduce(`*`, x=list(5,4,3,2), accumulate=TRUE)
# [1]   5  20  60 120

i2 <- seq(0,100,by=2)
i3 <- seq(0,100,by=3)
i5 <- seq(0,100,by=5)
Reduce(intersect, x=list(i2,i3,i5), accumulate=TRUE)
# [[1]]
#  [1]   0   2   4   6   8  10  12  14  16  18  20  22  24  26  28  30  32  34  36
# [20]  38  40  42  44  46  48  50  52  54  56  58  60  62  64  66  68  70  72  74
# [39]  76  78  80  82  84  86  88  90  92  94  96  98 100
# 
# [[2]]
#  [1]  0  6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96
# 
# [[3]]
# [1]  0 30 60 90