Question

I have to put thousand separator between numbers. I have done till now:

Input string

1852  
2589653  
586699  
8542.28

The find pattern

(?<=\d)(?=(?:\d{3})+(?!\d))  

replace-with

,  

result

1,852  
2,589,653  
586,699  
8,542.28 

---

TODO
I want to eliminate all year ranges from 1700 to 2010, from match-collection.

Anyone have any idea. All suggestions are welcome. Thanks in advance.

Answer 1

This is not a good way to use regular expressions.

Instead, use the string formatting features of your language:

• Use a simple regular expression to find the numbers, if you have to extract them from text.
• Convert them to floating point or integer numbers (as appropriate)
• Use a string format specifier to say you would like them output with a thousands separator.

For example, here’s a shell transcript where I extract a number from a string and format it with a comma thousands separator: (Python 2.x)

In [12]: import re

In [13]: number_pattern = re.compile(r"\d+(.\d+)") #positive integer or floating point number

In [14]: mystring = "The size of the rocket is 3141592.6."

In [15]: number_string = number_pattern.search(mystring).group() #extract the number as a string

In [16]: number_string
Out[16]: '3141592.6'

In [18]: number = float(number_string) #convert to number

In [19]: '{:,}'.format(number) #format with thousands separator
Out[19]: '3,141,592.6'

Doing it this way also makes eliminating ranges of numbers trivial.

if (number > 1700) or (number < 2100):
    pass #do something