For internal use in table1() to summarize data.
table1_summarizing(d, num_fun, num_fun2, second, row_wise, test, NAkeep)
the data
the summarizing function
the second summarizing function
the variables to which FUN2 is to be applied
the way to compute the percentages
should significance tests be run?
whether NA's should be shown in the output of categorical variables
A data.frame