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Numbers
Mathematical

Find the distance between two points

python
# problem description doesn't say 2D points ;)
from math import sqrt
print sqrt(sum((x-y)**2 for x,y in zip(a, b)))
from math import hypot
print hypot(x2-x1, y2-y1)
Output

Zero pad a number

Given the number 42, pad it to 8 characters like 00000042
python
"%08d" % 42

Right Space pad a number

Given the number 1024 right pad it to 6 characters "1024  "
python
"%-6s" % 1024
str(1024).rjust(6)
'{0: <6}'.format(1024)

Format a decimal number

Format the number 7/8 as a decimal with 2 places: 0.88
python
"%.2f" % (7 / 8.0)
round(7./8., 2)

Left Space pad a number

Given the number 73 left pad it to 10 characters "        73"
python
"%10s" % 73
Random

Generate a random integer in a given range

Produce a random integer between 100 and 200 inclusive
python
import random
random.randint(100, 200)
# uses best entropy source available (e.g. /dev/urandom, CryptGenRandom, ...)

import random
print random.SystemRandom().randint(100,200)

Generate a repeatable random number sequence

Initialise a random number generator with a seed and generate five decimal values. Reset the seed and produce the same values.
python
import random

random.seed(12345)
list1 = [random.randint(1,10) for x in range(5)]

random.seed(12345)
list2 = [random.randint(1,10) for x in range(5)]

assert(list1==list2)