dip {modeest} | R Documentation |
Computes Hartigan's DIP test statistic for testing unimodality, and additionally the modal interval. This function is taken from Martin Maechler's diptest package.
dip(x, full.result = FALSE, debug = FALSE)
x |
numeric. Vector of observations. |
full.result |
logical. If TRUE returns the full result
list, see below. |
debug |
logical. If TRUE , some tracing information is printed
(from the C routine). |
Depending on full.result
either a number, the dip statistic, or
a list with components
x |
the sorted unname() d data. |
n |
length(x) . |
dip |
the dip statistic |
lo.hi |
indices into x for lower and higher end of modal interval |
xl, xu |
lower and upper end of modal interval |
gcm, lcm |
(last used) indices for greatest convex minorant and the least concave majorant. |
mn, mj |
index vectors of length n for the GC minorant and
the LC majorant respectively. |
For n <= 3 where n <- length(x)
, the dip
statistic is always zero, i.e., there's no possible dip test.
Yong Lu lyongu+@cs.cmu.edu found in Oct 2003 that the code wasn't giving symmetric results for mirrored data (and was giving results of almost 1, and then found the reason, a misplaced ")" in the original Fortran code. This bug has been corrected for diptest version 0.25-0.
Martin Maechler maechler@stat.math.ethz.ch, based on earlier code from Dario Ringach dario@wotan.cns.nyu.edu
isoreg
for isotonic regression.
data(precip) plot(density(precip)) str(dip(precip, full = TRUE, debug = TRUE))