a list of thirteen components that summarize various features of x
after the data have been centered, scaled, and sorted by missingness
patterns. Components that might be of interest to the user include:
nmisa vector of length ncol(x) containing the number of missing
values for each variable in x. This vector has names that correspond
to the column names of x, if any.
rmatrix of response indicators showing the missing data patterns
in x. Dimension is (S,p) where S is the number of distinct
missingness patterns in the rows of x, and p is the number of
columns in x. Observed values are indicated by 1 and missing
values by 0. The row names give the number of observations in
each pattern, and the column names correspond to the column names of
x.