intergral:

In chenpanliao/cccR: Color contrast calculator with R

Usage

intergral(x, y)

Arguments

x
y

Examples

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function (x, y) 
{
    temp <- na.omit(data.frame(x, y))
    x <- temp$x
    y <- temp$y
    if (length(x) != length(y)) {
        stop("Length of x and y must be equal.")
    }
    if (length(x) < 2 | length(y) < 2) {
        stop("Length of x and y must larger than 1")
    }
    x.index <- order(x)
    xx <- x[x.index]
    yy <- y[x.index]
    n <- length(xx)
    xx.d <- xx[2] - xx[1]
    xx.cal <- numeric(n)
    for (k in 1:length(xx.cal)) {
        xx.cal[k] <- xx[1] + (k - 1) * xx.d
    }
    if (!all(xx == xx.cal)) {
        is.uniform <- F
        warning("x is not an arithmetic sequence.")
    }
    else {
        is.uniform <- T
    }
    if (is.uniform) {
        area <- ((xx[n] - xx[1])/2/(n - 1)) * (sum(yy) + sum(yy[2:(n - 
            1)]))
    }
    else {
        area.part <- numeric(n - 1)
        for (k in 1:(n - 1)) {
            area.part[k] <- (yy[k] + yy[k + 1]) * (xx[k + 1] - 
                xx[k])/2
        }
        area <- sum(area.part)
    }
    return(area)
  }

chenpanliao/cccR documentation built on May 10, 2019, 1:09 a.m.