Nonmem can only interpret numeric data. However, a factor or a character variable may very well be interpretable by Nonmem (e.g. "33"). This function tells whether Nonmem will be able to read it.
NMisNumeric(x, na.strings = ".", each = FALSE)The vector to check Don't export
Tolerated strings that do not translate to numerics. Default is to accept "." because it's common to write missing values that way to Nonmem (even if Nonmem will handle them as zeros rather than missing). Notice actual NA's are accepted so you may want to use na.strings=NULL if you don't code missings as "." and just do this when writing the data set to a delimited file (like NMwriteData will do for you).
Use each=TRUE to evaluate each element in a vector individually. The default (each=FALSE) is to return a single-length logical for a vector x summarizing whether all the elements are numeric-compatible.
TRUE or FALSE