Commas in Julia 1.0 Numbers of Any Kind

Question

I would like a function in Julia code, num2str, that would add commas or a specified delimiter, in the appropriate places on the left side of the decimal point for any kind of valid Julia number, including BigInt and BigFloat. It would return a string for printing.

For example:

flt1 = 122234.141567
println("flt1 num2str($flt1) = ", num2str(flt1))
# Expected output is:
flt1 num2str(122234.141567) = 122,234.141567

I want to use this function with the print and println built-in functions.

user_10316987 · Answer

This question was partially answered here, i.e, for integers. The following function should answer the need for floats and "big" numbers.

"""
 For any valid number, add appropriate delimiters.
 See "Regular Expressions Cookbook," by Goyvaerts and Levithan, O'Reilly, 2nd Ed, 
 p. 402, for Regex that inserts commas into integers returning a string.
"""
function num2str(num::Number; delim=",")
   decimal_point = "."
   str = string(num)
   strs = split(str, decimal_point)
   left_str = strs[1]
   right_str = length(strs) > 1 ? strs[2] : ""
   left_str = replace(left_str, r"(?<=[0-9])(?=(?:[0-9]{3})+(?![0-9]))" => delim)
   decimal_point = occursin(decimal_point, str) ? decimal_point : ""
   return left_str * decimal_point * right_str
end

# Test integers, BigInts, floats, and BigFloats:
int0 = 0
int1 = 123
int2 = 123456789
big1 = big"123"
big2 = big"123456789123456789"
flt1 = 122234.141567
flt2 = 7.12345e9
big3 = big"260123.0"
big4 = big"7.12345e9"

setprecision(20)
println("int0 num2str($int0) 				 = ", num2str(int0))
println("int1 num2str($int1) 				 = ", num2str(int1))
println("int2 num2str($int2) 			 = ", num2str(int2))
println("big1 num2str($big1) 				 = ", num2str(big1))
println("big2 num2str($big2) 		 = ", num2str(big2))
println("big2 num2str($big2) delim is _ 	 = ", num2str(big2, delim="_"))
println("flt1 num2str($flt1) 			 = ", num2str(flt1))
println("flt1 num2str($flt1) delim is _ 		 = ", num2str(flt1, delim="_"))
println("flt2 num2str($flt2) 			 = ", num2str(flt2))
println("big3 num2str($big3) 			 = ", num2str(big3))
println("big4 num2str($big4) 			 = ", num2str(big4))
println("big4 num2str($big4) delim is _ 		 = ", num2str(big4, delim="_"))

## ============================== Output ===================================
int0 num2str(0)                                  = 0
int1 num2str(123)                                = 123
int2 num2str(123456789)                          = 123,456,789
big1 num2str(123)                                = 123
big2 num2str(123456789123456789)                 = 123,456,789,123,456,789
big2 num2str(123456789123456789) delim is _      = 123_456_789_123_456_789
flt1 num2str(122234.141567)                      = 122,234.141567
flt1 num2str(122234.141567) delim is _           = 122_234.141567
flt2 num2str(7.12345e9)                          = 7.12345e9
big3 num2str(2.60123e+05)                        = 2.60123e+05
big4 num2str(7.12345e+09)                        = 7.12345e+09
big4 num2str(7.12345e+09) delim is _             = 7.12345e+09

I expect the ability to add comma delimiters will eventually be added to either print/println and/or @printf. Until then, this seems to work.

Commas in Julia 1.0 Numbers of Any Kind

1 Answers