Using Theorem 1 from Hudgens (2005) we can check whether an NPMLE exists. This procedure is implemented in this function.
existenceNPMLE(intervals, supportdf)A data.frame with 4 columns containing half-open intervals (left open, right closed) and an indicator whether the interval results from a censored transition or truncation:
L:Left side of interval;
R:Right side of interval;
cens:Indicator whether interval resulted from censoring or truncation (1 = censoring, 0 = truncation);
id:(required) Identifier for the observation this interval belongs to (numeric/integer);
Note that the truncation intervals need to be in the form (N, Inf] with N a numeric value.
A data from containing 2 columns indicating the support intervals:
L:Left side of interval;
R:Right side of interval;