Convert from billion to million and vice versa

Question

Suppose I have the following data frame named DF. I would like to convert all the values in the Revenue column to the same unit.

Answer 1

One idea,

new <- ifelse(gsub('.*\\s+', '', DF$Revenue) == 'bn',
              as.numeric(gsub('[A-Za-z]', '', DF$Revenue))*1000, DF$Revenue)

new[!grepl('Mn', new)] <- paste(new[!grepl('Mn', new)], 'Mn', sep = ' ')
DF$Revenue <- new

DF
#  Brands  Revenue
#1      A 50100 Mn
#2      B 41200 Mn
#3      C  32.5 Mn
#4      D 15100 Mn

To do the opposite then,

new <- ifelse(gsub('.*\\s+', '', DF$Revenue) == 'Mn',
               as.numeric(gsub('[A-Za-z]', '', DF$Revenue))/1000, DF$Revenue)

 new[!grepl('bn', new)] <- paste(new[!grepl('bn', new)], 'bn', sep = ' ')
 DF$Revenue <- new
 DF
#  Brands   Revenue
#1      A   50.1 bn
#2      B   41.2 bn
#3      C 0.0325 bn
#4      D   15.1 bn