R factor dataframe of coordinates

Question

I have a dataframe and a column of ordered pairs of (latitude, longitude) as factors within that dataframe that I would like to extract into columns of just the latitude and longitude values separately into numerics. How would I get rid of the commas and parentheses and place the factors into their own columns as numbers?

Answer 1

Several ways, but I'll focus on strcapture . My sample data:

somecoords <- c("(1.1,2.2)","(3.3,4.4)")
# if not 'character', then
somecoords <- as.character(somecoords)

strcapture starts with a vector of strings and returns a data.frame :

strcapture("\\D*(-?[0-9]+\\.?[0-9]*),(-?[0-9]+\\.?[0-9]*)\\D?.*$",
           somecoords, proto = list(num1=0, num2=0))
#   num1 num2
# 1  1.1  2.2
# 2  3.3  4.4

Regex walk-through:

• \\D* zero or more non-digit characters
• (...) a capture group, saved by strcapture into a column
• -? a literal dash/hyphen, optional
• [0-9]+ one or more digits
• \\.? literal dot, optional, in case there are whole-number coordinates in your data
• [0-9]* zero or more digits
• , literal comma
• \\D?.* optional non-digit character, followed by zero or more of anything
• $ end of string (perhaps not required, since .* should have expanded fully