[R] sort a data frame according to roman characters

[Luis Ridao Cruz]

R-help,

I have a data frame with one column containing roman numbers
The data are not sorted as : I    II   III  IV   V    VI   VII  VIII IX
  X    XI   XII  XIII XIV  XV

Using data[order(data$Roman),] does not do the job.

How can this be done?

Thanks in advance.