Python: Make division always produce real numbers

A division of 7/3 in Python will gives a result of 2. However, this is not correct. Since Python always assume that the numbers are whole numbers, the result will be truncated from 2.5 to 2.

A work around is to write one or both of the numbers as a decimal:

>>> print 7/3.0
2.5

>>> print 7.0/3
2.5

>>> print 7.0/3.0
2.5

In order to change this behaviour of Python, throughout the program execution, so that Python will always produce real numbers, a module division has to be imported.

>>> from __future__ import division

>>> print 7/3
2.5

Python: Put comma(s) to numbers

This script will put commas between each group of three digits number. For example, 1234567 will become 1,234,567.

import re

putComma = lambda x: (",".join(re.findall("d{1,3}",
str(x)[::-1])))[::-1]

print putComma(1234567) # 1,234,567
print putComma(12345678) # 12,345,678
print putComma(123456789) # 123,456,789
print putComma(1212) # 1,212

Python: Prime Number

This Python script will generate a list of prime number.

def isPrime(x):
    for i in range(2, x):
        if x%i == 0:
            return false
        return true

for c in range(1,10):
    if isPrime(c):
        print c,

output:

>>> 1 2 3 5 7