stack.offset()

stack.offset([offset])

If offset is specified, sets the offset accessor to the specified function or array and returns this stack generator. If offset is not specified, returns the current offset acccesor, which defaults to stackOffsetNone; this uses a zero baseline. See stack offsets for the built-in offsets.

If offset is a function, it is passed the generated series array and the order index array. The offset function is then responsible for updating the lower and upper values in the series array to layout the stack. For example, the default offset is defined as:

function offsetNone(series, order) {
  if (!((n = series.length) > 1)) return;
  for (var i = 1, s0, s1 = series[order[0]], n, m = s1.length; i < n; ++i) {
    s0 = s1, s1 = series[order[i]];
    for (var j = 0; j < m; ++j) {
      s1[j][1] += s1[j][0] = s0[j][1];
    }
  }
}