Question

Manipulate character string using gsub() and perform multivariate data cleaning efficiently in R. 

• Convert all the million values into Billion as 1 M = 0.001 B
• Remove unnecessary symbols B, M and have only numerical values.

Answer 1

gsubfn is perfect for this task:

library(gsubfn)
as.vector(sapply(gsubfn("[A-Z]", list(B="* 1", M= "* 1e-3"), x), 
                                      function(x) eval(parse(text=x))))
#[1] 1.200 2.500 0.808

data

x <- c("1.2 B", "2.5 B", "808 M")