Formate a number with commas

[John Posner]

On 2:59 PM, noydb wrote:
> How do you format a number to print with commas?

I would readily admit that both the "locale" module and "format" method
are preferable to this regular expression, which certainly violates the
"readability counts" dictum:

    r"(?<=\d)(?=(\d\d\d)+$)"

# python 2.6.6
import re
find_blocks = re.compile(r"(?<=\d)(?=(\d\d\d)+$)")
for numstr in "1 12 123 1234 12345 123456 1234567 12345678".split():
    print find_blocks.sub("," , numstr)

output is:

1
12
123
1,234
12,345
123,456
1,234,567
12,345,678

-John