Probability distribution

对于一个特定类型的分布，R配套了4个函数：

• d- gives the “probability density” or “probability mass”，即pdf或pmf
• p- gives the distribution function，即cdf
• q- gives the quantile function，即下分位数函数
• r- generates random deviates，即生成该分布随机变量的realization

Uniform Distribution

• dunif(x, min = 0, max = 1, log = FALSE)
• punif(q, min = 0, max = 1, lower.tail = TRUE, log.p = FALSE)
• runif(n, min = 0, max = 1)

Binomial Distribution

• dbinom(x, size, prob, log = FALSE)
• pbinom(q, size, prob, lower.tail = TRUE, log.p = FALSE)
• rbinom(n, size, prob)

Poisson Distribution

• dpois(x, lambda, log = FALSE)
• ppois(q, lambda, lower.tail = TRUE, log.p = FALSE)
• qpois(p, lambda, lower.tail = TRUE, log.p = FALSE)
• rpois(n, lambda)