Seek the significant cutoff value for a continuous variable, which will
be transformed into a classification, for linear regression,
logistic regression, logrank analysis and cox regression. First of all,
all combinations will be gotten by combn() function. Then n.per argument,
abbreviated of total number percentage, will be used to remove the combination
of smaller data group. In logistic, Cox regression and logrank analysis,
we will also use p.per argument, patient percentage, to filter the lower
proportion of patients in each group. Finally, p value in regression
results will be used to get the significant combinations and output
relevant parameters. In this package, there is no limit to the number of
cutoff points, which can be 1, 2, 3 or more. Still, we provide 2 methods,
typical Bonferroni and Duglas G (1994)