set.seed（）函数在R中影响随机

Question

Today i first met a set.seed function in R. It's useful in same times, and i understand how to use it. But i have a small problem - how to choose a real good number as a first parameter in this function?

From that question a get another - how the first parameter from set.seed() function influence into random in R? Maybe if i understand the last, i will take the answer of first. Thanks a lot.

Answer 1

In a nutshell:
By setting set.seed() you specify the starting-point for all "pseudo random number generators" that create the random numbers in R . See ?set.seed

As computers are very deterministic there is nothing like a real "random number". Computers always have to use an algorithm to generate so called "pseudo random numbers". These generators/algorithms work (very often) iterative so the next number is influenced by its predecessor. set.seed() defines the initial predecessor and thereby makes pseudo random numbers reproducible. Which number you choose is irrelevant in most cases.

(see here: http://en.wikipedia.org/wiki/Pseudorandom_number_generator )